bicycle-forum.net Promoting biking discussion.

Main Date: 22 Jun 2007 10:51:11 From: bw2117@yahoo.com Subject: Safe to lengthen a chain? I cut a new PC59 chain one link too short. Is it safe to add that link back on? Thanks.   Date: 25 Jun 2007 13:19:38 From: datakoll Subject: Re: Safe to lengthen a chain? On Jun 25, 8:45 am, Peter Cole <peter_c...@comcast.net > wrote: > jobst.bra...@stanfordalumni.org wrote: > > Steve Gravrock writes: > > >>> PowerLinks take much power to disengage on a used (dirty) chain. I > >>> found that using pliers diagonally, end-to-end of the link, > >>> compresses it in both directions enough to open it. That is, if > >>> you need to open the chain in the field, as one does if a stick > >>> damages the derailleur, a CPR-9 chain tool is the way to do it. > >>> You probably cannot get a PowerLink open without tools. > > >> I've had the same experience with 8-speed PowerLinks. I run some > >> kind of SRAM 8-speed chain, probably the pc48, on my snow bike and > >> opening the PowerLink is a nightmare. The 9 speed PowerLinks are a > >> different animal though. They open very easily without tools even > >> when the chain is dirty. I don't know what makes the difference, but > >> it's pretty dramatic. > > > The 8sp PowerLink has a stepped recess in the 'hole' plate and to > > disengage the pins, the 'hole' plate must be pressed inward the depth > > of the tiny ridge that fits in the pin groove and retains the pins. > > If you have a close-up view of that link similar to the one at: > > >http://www.speedgoat.com/product.asp?part=38807&cat=80&brand=55 > > > or: > > >http://www.sheldonbrown.com/harris/chains.html > > > the reason for easier separation should be apparent. I Don't have one > > and would need to visit the local bicycle shop to investigate. > > > Jobst Brandt > > The older Craig "Super Link" didn't have a stepped recess in the hole > and as a result was much easier to disconnect. I think the SRAM design > is a bad one, destroying most of the convenience of a quick link.- Hide quoted text - > > - Show quoted text - use pliers     Date: 25 Jun 2007 11:35:16 From: Peter Cole Subject: Re: Safe to lengthen a chain? datakoll wrote: > On Jun 25, 8:45 am, Peter Cole <peter_c...@comcast.net> wrote: >> The older Craig "Super Link" didn't have a stepped recess in the hole >> and as a result was much easier to disconnect. I think the SRAM design >> is a bad one, destroying most of the convenience of a quick link.- Hide quoted text - >> >> - Show quoted text - > > use pliers > I have, but as Jobst points out, dirty quick links can be impossible to open. It may be a quick "link", but it's a very tedious "unlink". The Craig's were much better.   Date: 24 Jun 2007 20:28:52 From: Nate Knutson Subject: Re: Safe to lengthen a chain? On Jun 24, 6:05 am, still me <wheeled...@yahoo.com > wrote: > On Sat, 23 Jun 2007 22:45:35 -0700, Nate Knutson <biken...@riseup.net> > wrote: > > >The explanation I've always heard is that the interference fit between > >pin and outer link needs to be made tighter on modern chains, and is > >prone to getting messed up and overly weakened during disconnection > >and reconnection. > > So it the head different than historical chains? Is it just the fact > that it went out once and came back in? It seems that unless the > design is different, that a tighter initial fit than historical would > just give a tighter refit that I'd normally have... and it would work > as well as historical chains (in other words, forever :-). > > I'm not trying to buck the right technique, just wondering what the > real difference is here. The issue is that the parts of the pin and/or outer link that press together are prone to getting worn during the disconnection/ reconnection process, so when you put it back together the amount of interference is reduced and the connection is weaker or unreliable or whatever.   Date: 24 Jun 2007 09:12:48 From: andresmuro@aol.com Subject: Re: Safe to lengthen a chain? On Jun 24, 9:10 am, Booker C. Bense <bbense+rec.bicycles.tech.Jun. 24...@telemark.slac.stanford.edu > wrote: > In article <467d7629$0$14133$742ec...@news.sonic.net>, > > <jobst.bra...@stanfordalumni.org> wrote: > > >PowerLinks take much power to disengage on a used (dirty) chain. I > >found that using pliers diagonally, end-to-end of the link, compresses > >it in both directions enough to open it. That is, if you need to open > >the chain in the field, as one does if a stick damages the derailleur, > >a CPR-9 chain tool is the way to do it. You probably cannot get a > >PowerLink open without tools. > > This is simply not true in my experience, there is a trick to it > but once mastered SRAM powerlinks actually get easier to open > with use. I have them on all my bikes and can easily break the > chain with just my hands, no tools required. > > I wish could explain the trick fully, but I can't. The basics are to > make a Z with the link and apply shear, but not compressive > force. If you squeeze the link, it won't slide. > > I did have a lot of trouble with these at the start, but since I mastered > the trick I haven't had to resort to tools to break the power > link over the last 4 years. > > _ Booker C. Bense I seem to have the same experience most of the time. However, once in a while I end up calling the chain all kinds of things. I refuse to use pliers on the grounds that it should come apart with zen gentleness. Then, after a few minutes of name calling a la "jim beam and ed trollan" I get the pliers. Same thing is for tires. I seem to be able to get out almost any tire by hand impressing the populous. On occasion, I run into the tire-rim combination that will make me the Make-me-laugh of the world. Showmanship has its price. Andres   Date: 24 Jun 2007 07:50:55 From: Johnny Sunset Subject: Re: Safe to lengthen a chain? On Jun 24, 9:22 am, Michael Warner wrote: > On Fri, 22 Jun 2007 22:27:55 -0700, Johnny Sunset wrote: > > Some of my bikes have chains with three (3) Powerlinks with no ill > > effects. > > Except that the resulting chain is ridiculously long and heavy :-) Hey, its only 250 links! -- Tom Sherman - Holstein-Friesland Bovinia The weather is here, wish you were beautiful   Date: 24 Jun 2007 13:58:56 From: datakoll Subject: Re: Safe to lengthen a chain? chain pins http://www.universalcycles.com/shopping/index.php?category=276 chains wear out sometimes only at two links. a splice from the part cut off when installing, and saved coated with linseed, in the chain tool and parts box, along with the pins bought for a rainy day which is when the random links wear may occur, may be splice in saving the chain. what's unknown is known, that is the chain may proceed to the usual claimed life of 10-15K miles or fail sooner. What causes this is unknown but suspected as operator error rather than the expletive deleted park's chain tool. It does 'seem' unlikely 'waht light thru yonder' a modifed chain would fail but just wear out sooner. power links jammed with grit are tough to remove but dribbling a bit of thinner on the link then using the link tool you made from a walmart $2 vise grips, using your nabs grinder... for arthritis?   Date: 23 Jun 2007 22:45:35 From: Nate Knutson Subject: Re: Safe to lengthen a chain? On Jun 23, 7:45 am, still me <wheeled...@yahoo.com > wrote: > On Sat, 23 Jun 2007 06:19:03 -0700, Kenny <Postoas...@gmail.com> > wrote: > > >On Jun 23, 1:51 am, "bw2...@yahoo.com" <bw2...@yahoo.com> wrote: > >> I cut a new PC59 chain one link too short. Is it safe to add that > >> link back on? > > >> Thanks. > > >To be absolutely safe use a snap link or powerlink. > > Retro oriented question: Why is this true with "modern" chains? Do > they peen the heads larger ? > > If using SRAM chains, at what point in the line does this become an > issue - pc48? 58? The explanation I've always heard is that the interference fit between pin and outer link needs to be made tighter on modern chains, and is prone to getting messed up and overly weakened during disconnection and reconnection. When I was still a newbie I broke a PC48 that I had reconnected the traditional way. It happened during a front shift under pretty heavy load and probably fairly poor technique, but who knows how much of a factor that really was. SRAM specifically says to only ever use powerlinks on all their 8 and 9 speed chains. Basically no modern derailer chains should be connected the traditional way unless the manufacturer tells you to, which I don't think any of them do. Of note here is that KMC, whose chains are probably the most commonly specced on bikes, is pretty darn bad about publicizing which of their Missinglinks go with what chains or that traditional reconnection isn't okay (which you do see them saying if you look hard enough). It's kind of a mess and people end up riding sketchy stuff because of it.     Date: 24 Jun 2007 13:05:11 From: still me Subject: Re: Safe to lengthen a chain? On Sat, 23 Jun 2007 22:45:35 -0700, Nate Knutson <bikenate@riseup.net > wrote: >The explanation I've always heard is that the interference fit between >pin and outer link needs to be made tighter on modern chains, and is >prone to getting messed up and overly weakened during disconnection >and reconnection. So it the head different than historical chains? Is it just the fact that it went out once and came back in? It seems that unless the design is different, that a tighter initial fit than historical would just give a tighter refit that I'd normally have... and it would work as well as historical chains (in other words, forever :-). I'm not trying to buck the right technique, just wondering what the real difference is here.       Date: 24 Jun 2007 15:41:53 From: Booker C. Bense Subject: Re: Safe to lengthen a chain? In article <prqs73dnnspqmie2jb39bj08o1v6db2bug@4ax.com >, still me <wheeledBob@yahoo.com > wrote: >On Sat, 23 Jun 2007 22:45:35 -0700, Nate Knutson <bikenate@riseup.net> >wrote: > >>The explanation I've always heard is that the interference fit between >>pin and outer link needs to be made tighter on modern chains, and is >>prone to getting messed up and overly weakened during disconnection >>and reconnection. > >So it the head different than historical chains? Yes. they are made to a different design. > >I'm not trying to buck the right technique, just wondering what the >real difference is here. Poke around Sheldon Brown's website and you will find a good explaination of the difference between old and new chains. _ Booker c. Bense   Date: 23 Jun 2007 18:23:05 From: Chris Nelson Subject: Re: Safe to lengthen a chain? On Jun 23, 8:58 pm, jobst.bra...@stanfordalumni.org wrote: > Chris Nelson writes: > >>>>>> PowerLinks take much power to disengage on a used (dirty) > >>>>>> chain. I found that using pliers diagonally, end-to-end of the > >>>>>> link, compresses it in both directions enough to open it. That > >>>>>> is, if you need to open the chain in the field, as one does if > >>>>>> a stick damages the derailleur, a CPR-9 chain tool is the way > >>>>>> to do it. You probably cannot get a PowerLink open without > >>>>>> tools. >>>>> You can, but it takes a multitude of four letter > >>>>>> words strung >>>>> together with rage. The Connex power > >>>>>> however, is easy to operate >>>>> by fingers. > >>>> The Connex link is no different from the PowerLink in that it > >>>> must be compressed laterally to disengage. What makes you think > >>>> that a chain in similar condition to the one that doesn't freely > >>>> release a PowerLink will do so for a Connex? > >>> No lateral compression required. See:http://www.connexchain.com/ > >>> Click on Products->Connectors and one of the three Connex link > >>> links. There is an animation on how it goes together. Removal > >>> goes in reverse. > >> Not exactly. Lateral compression is required to slide the pin out > >> of engagement. The step and re-entrant profile is apparent in the > >> picture. What is simpler is that the two halves of the link are > >> identical, but the method of retention is the same as PowerLink. > >> The design makes use of the lateral angle that these chains require > >> to have a cross-over chain line. When the chain is straight, that > >> little clearance is enough to raise the pis out of the 'lock' slot > >> and into the release hole, which on the Connex is around the corner > >> as it must be for this design. > >> - Show quoted text - > > What is missing? > > > Absolute nonsense. I have one in my hand right now and I can remove > > without any lateral compression. Zero-nada-none. The ONLY action is > > to move the pins closer together, with the constraint being the 90 > > degree angle to the rest of the chain as depicted in the animation. > > What is not visible in the video, is that the slots in the pins have > reliefs that allow sliding out when turned sideways. I assume that is > why your assessment is correct. Not having such a link I looked at > the picture which shows that the pin is blocked similarly to the > PowerLink when straight ahead. That it is undercut on the sides is > not visible. > > Jobst Brandt- Hide quoted text - > > - Show quoted text - Actually the pins are completely round. The safety comes from oversized links that collide with adjacent outer links when applying removal action in a parallel alignment. Chris     Date: 24 Jun 2007 01:59:28 From: still me Subject: Re: Safe to lengthen a chain? On Sat, 23 Jun 2007 18:23:05 -0700, Chris Nelson <smilin321@hotmail.com > wrote: >Actually the pins are completely round. The safety comes from >oversized links that collide with adjacent outer links when applying >removal action in a parallel alignment. > >Chris Well, that argument aside... is it safe for me to lengthen or shorten PC48 chains the old fashioned way with a chain pin tool ?       Date: 28 Jun 2007 12:52:32 From: Chris Nelson Subject: Re: Safe to lengthen a chain? On Jun 27, 10:59 pm, Patrick Lamb <pdl678NOS...@comcast.net > wrote: > On Tue, 26 Jun 2007 12:08:29 -0700, Chris Nelson > > > > > > <smilin...@hotmail.com> wrote: > >On Jun 26, 2:31 pm, jobst.bra...@stanfordalumni.org wrote: > >> Chris Nelson writes: > >> > Modern chain pins are beveled on each side for added strength. Once > >> > the pin is pushed through it flattens out the bevel and weakens that > >> > link. > > >> I think you have that backward. 10-speed chain pins have no bevel and > >> are flush with the side plate. When pushed in, the original pin > >> broaches a larger hole in the side plate so it has no suitable press > >> fit and can disengage. The damage is not apparent because the other > >> end of the pin still has a press fit and masks the loose fit in the > >> re-engaged side plate. > > >> It is not that any part of the chain breaks (weakens that link) but > >> that the side plate bends outward losing support from its pin. > > >> Jobst Brandt > > >Pop a pin out of a scrap chain and examine it closely (A microscope > >would be preferable). You will see that the end that traveled through > >the links has lost its bevel and the end that did not have to travel > >through the links has retained its bevel. > > >Chris > > Are you confusing "bevel" with "peened end?" > > Pat > > Email address works as is.- Hide quoted text - > > - Show quoted text - I confused "bevel" with something that may be described as a "lip", "flare", or "peened end". Peened seems to imply that there was an impact of some sort to form the "flare". Not sure of the manufacturing process. Chris       Date: 27 Jun 2007 07:05:00 From: Chris Nelson Subject: Re: Safe to lengthen a chain? On Jun 27, 9:03 am, Peter Cole <peter_c...@comcast.net > wrote: > Chris Nelson wrote: > > On Jun 26, 9:29 pm, jobst.bra...@stanfordalumni.org wrote: > >> Chris Nelson writes: > >>>>> Both sides are beveled, there is no wrong end. The bevels are bent > >>>>> in the direction that would allow the pin to be removed. > >>>> From what you write, I suspect you don't know what a bevel is. > >>>> There is no way to orient a bevel on the end of a pin. > >>>> Again: How is does pushing the pin out destroy the bevel? > >>>> As in : "You will see that the end that traveled through the links > >>>> has lost its bevel and the end that did not have to travel through > >>>> the links has retained its bevel." > >>> Push a pin out and look for yourself. Wanna borrow my Park CT-3 ? > >> Well, I dropped by the bicycle shop and picked up such a chain and, > >> yes, you have your terms mixed up. The pins are flared on both ends, > >> not beveled. A bevel at the end of a pin/shaft is a taper used to > >> prevent broaching when pressing the circular profile into a round > >> hole. > > >> See:http://www.radax.com/store.asp?pid=14559 > > >> Ten speed chains have flared ends and it is the flare that breaks off > >> when pushed out. This leaves a sharp jagged end that cannot be > >> reasonably pressed into a chain. The ends of the Shimano Dura Ace > >> chain is swaged after insertion by forming a dimple in each end. > > >> Jobst Brandt > > > Flared would be a more accurate description than beveled, my mistake. > > Actually, the descriptions are opposite. > > > > > But my point still stands, that a pin when removed and reinserted > > results in a weaker link because of damage to the pin "flare". In > > fact, the instructions that come with Shimano chain warns against > > reinserting pins. > > Which is why I stopped using Shimano chains years ago. I have not had > Sachs 8-speed chains fail after joining with a pin after I discovered > how critical it was to make sure the pin protrudes exactly the right > amount from the side plates. > > I have not had a quick link fail, but for one to come undone without > damage, it would seem that the only possible way would be to have the > link undergo compression. > > I pulled my daughter for years up steep off-road trails, with her weight > up to 90 lb and mine at 230. That, combined with very low gearing and > long cranks probably represented chain tensions beyond that which most > riders generate.- Hide quoted text - > > - Show quoted text - SRAM also uses "flared" pins for strength. The exception being the special connector pin that there is only one of(if not using the Powerlink). The removal and reinstalling of the chain by pins other than the special connector pin will result in a chain whose integrity has been compromised. Not sure of the effects of repeated connector pin removal. SRAM instructions cautions the user to use the Powerlink. Chris         Date: 28 Jun 2007 09:39:45 From: Peter Cole Subject: Re: Safe to lengthen a chain? Chris Nelson wrote: > On Jun 27, 9:03 am, Peter Cole <peter_c...@comcast.net> wrote: >> Chris Nelson wrote: >>> On Jun 26, 9:29 pm, jobst.bra...@stanfordalumni.org wrote: >>>> Chris Nelson writes: >>>>>>> Both sides are beveled, there is no wrong end. The bevels are bent >>>>>>> in the direction that would allow the pin to be removed. >>>>>> From what you write, I suspect you don't know what a bevel is. >>>>>> There is no way to orient a bevel on the end of a pin. >>>>>> Again: How is does pushing the pin out destroy the bevel? >>>>>> As in : "You will see that the end that traveled through the links >>>>>> has lost its bevel and the end that did not have to travel through >>>>>> the links has retained its bevel." >>>>> Push a pin out and look for yourself. Wanna borrow my Park CT-3 ? >>>> Well, I dropped by the bicycle shop and picked up such a chain and, >>>> yes, you have your terms mixed up. The pins are flared on both ends, >>>> not beveled. A bevel at the end of a pin/shaft is a taper used to >>>> prevent broaching when pressing the circular profile into a round >>>> hole. >>>> See:http://www.radax.com/store.asp?pid=14559 >>>> Ten speed chains have flared ends and it is the flare that breaks off >>>> when pushed out. This leaves a sharp jagged end that cannot be >>>> reasonably pressed into a chain. The ends of the Shimano Dura Ace >>>> chain is swaged after insertion by forming a dimple in each end. >>>> Jobst Brandt >>> Flared would be a more accurate description than beveled, my mistake. >> Actually, the descriptions are opposite. >> >> >> >>> But my point still stands, that a pin when removed and reinserted >>> results in a weaker link because of damage to the pin "flare". In >>> fact, the instructions that come with Shimano chain warns against >>> reinserting pins. >> Which is why I stopped using Shimano chains years ago. I have not had >> Sachs 8-speed chains fail after joining with a pin after I discovered >> how critical it was to make sure the pin protrudes exactly the right >> amount from the side plates. >> >> I have not had a quick link fail, but for one to come undone without >> damage, it would seem that the only possible way would be to have the >> link undergo compression. >> >> I pulled my daughter for years up steep off-road trails, with her weight >> up to 90 lb and mine at 230. That, combined with very low gearing and >> long cranks probably represented chain tensions beyond that which most >> riders generate.- Hide quoted text - >> >> - Show quoted text - > > SRAM also uses "flared" pins for strength. The exception being the > special connector pin that there is only one of(if not using the > Powerlink). Where did you see this? I know Shimano uses special pins, but I have never seen these with a SRAM chain, nor in their manual. The removal and reinstalling of the chain by pins other > than the special connector pin will result in a chain whose integrity > has been compromised. Not sure of the effects of repeated connector > pin removal. SRAM instructions cautions the user to use the Powerlink. I didn't see that caution in the online manual.         Date: 28 Jun 2007 00:38:15 From: Subject: Re: Safe to lengthen a chain? - Hide quoted text - - Show quoted text - - Hide quoted text - - Show quoted text - - Hide quoted text - - Show quoted text - - Hide quoted text - - Show quoted text - - Hide quoted text - - Show quoted text - I think she's got it! I think she's got it, 'enry 'iggins! Google is grasping for recognition where it isn't with these insertions. Jobst Brandt       Date: 25 Jun 2007 08:15:52 From: Peter Cole Subject: Re: Safe to lengthen a chain? still me wrote: > On Sat, 23 Jun 2007 18:23:05 -0700, Chris Nelson > <smilin321@hotmail.com> wrote: > >> Actually the pins are completely round. The safety comes from >> oversized links that collide with adjacent outer links when applying >> removal action in a parallel alignment. >> >> Chris > > Well, that argument aside... is it safe for me to lengthen or shorten > PC48 chains the old fashioned way with a chain pin tool ? It can be, but it's a little tricky. You want to carefully look at how much pin is extending above the side plate on the factory joined links and make sure your join is exactly the same (on both sides) -- it really requires a bit of precision, and a good chain tool.   Date: 23 Jun 2007 16:36:10 From: Chris Nelson Subject: Re: Safe to lengthen a chain? On Jun 23, 7:10 pm, jobst.bra...@stanfordalumni.org wrote: > Chris Nelson writes: > >>>> PowerLinks take much power to disengage on a used (dirty) chain. > >>>> I found that using pliers diagonally, end-to-end of the link, > >>>> compresses it in both directions enough to open it. That is, if > >>>> you need to open the chain in the field, as one does if a stick > >>>> damages the derailleur, a CPR-9 chain tool is the way to do it. > >>>> You probably cannot get a PowerLink open without tools. > >>> You can, but it takes a multitude of four letter words strung > >>> together with rage. The Connex power however, is easy to operate > >>> by fingers. > >> The Connex link is no different from the PowerLink in that it must > >> be compressed laterally to disengage. What makes you think that a > >> chain in similar condition to the one that doesn't freely release a > >> PowerLink will do so for a Connex? > > No lateral compression required. > > See:http://www.connexchain.com/ > > Click on Products->Connectors and one of the three Connex link > > links. There is an animation on how it goes together. Removal goes > > in reverse. > > Not exactly. Lateral compression is required to slide the pin out of > engagement. The step and re-entrant profile is apparent in the > picture. What is simpler is that the two halves of the link are > identical, but the method of retention is the same as PowerLink. The > design makes use of the lateral angle that these chains require to > have a cross-over chain line. When the chain is straight, that little > clearance is enough to raise the pis out of the 'lock' slot and into > the release hole, which on the Connex is around the corner as it must > be for this design. > > Jobst Brandt- Hide quoted text - > > - Show quoted text - Absolute nonsense. I have one in my hand right now and I can remove without any lateral compression. Zero-nada-none. The ONLY action is to move the pins closer together, with the constraint being the 90 degree angle to the rest of the chain as depicted in the animation. Chris     Date: 24 Jun 2007 00:58:16 From: Subject: Re: Safe to lengthen a chain? Chris Nelson writes: >>>>>> PowerLinks take much power to disengage on a used (dirty) >>>>>> chain. I found that using pliers diagonally, end-to-end of the >>>>>> link, compresses it in both directions enough to open it. That >>>>>> is, if you need to open the chain in the field, as one does if >>>>>> a stick damages the derailleur, a CPR-9 chain tool is the way >>>>>> to do it. You probably cannot get a PowerLink open without >>>>>> tools. >>>>> You can, but it takes a multitude of four letter >>>>>> words strung >>>>> together with rage. The Connex power >>>>>> however, is easy to operate >>>>> by fingers. >>>> The Connex link is no different from the PowerLink in that it >>>> must be compressed laterally to disengage. What makes you think >>>> that a chain in similar condition to the one that doesn't freely >>>> release a PowerLink will do so for a Connex? >>> No lateral compression required. See:http://www.connexchain.com/ >>> Click on Products->Connectors and one of the three Connex link >>> links. There is an animation on how it goes together. Removal >>> goes in reverse. >> Not exactly. Lateral compression is required to slide the pin out >> of engagement. The step and re-entrant profile is apparent in the >> picture. What is simpler is that the two halves of the link are >> identical, but the method of retention is the same as PowerLink. >> The design makes use of the lateral angle that these chains require >> to have a cross-over chain line. When the chain is straight, that >> little clearance is enough to raise the pis out of the 'lock' slot >> and into the release hole, which on the Connex is around the corner >> as it must be for this design. >> - Show quoted text - What is missing? > Absolute nonsense. I have one in my hand right now and I can remove > without any lateral compression. Zero-nada-none. The ONLY action is > to move the pins closer together, with the constraint being the 90 > degree angle to the rest of the chain as depicted in the animation. What is not visible in the video, is that the slots in the pins have reliefs that allow sliding out when turned sideways. I assume that is why your assessment is correct. Not having such a link I looked at the picture which shows that the pin is blocked similarly to the PowerLink when straight ahead. That it is undercut on the sides is not visible. Jobst Brandt       Date: 26 Jun 2007 21:42:00 From: Chris Nelson Subject: Re: Safe to lengthen a chain? On Jun 26, 9:29 pm, jobst.bra...@stanfordalumni.org wrote: > Chris Nelson writes: > >>> Both sides are beveled, there is no wrong end. The bevels are bent > >>> in the direction that would allow the pin to be removed. > >> From what you write, I suspect you don't know what a bevel is. > >> There is no way to orient a bevel on the end of a pin. > >> Again: How is does pushing the pin out destroy the bevel? > >> As in : "You will see that the end that traveled through the links > >> has lost its bevel and the end that did not have to travel through > >> the links has retained its bevel." > > Push a pin out and look for yourself. Wanna borrow my Park CT-3 ? > > Well, I dropped by the bicycle shop and picked up such a chain and, > yes, you have your terms mixed up. The pins are flared on both ends, > not beveled. A bevel at the end of a pin/shaft is a taper used to > prevent broaching when pressing the circular profile into a round > hole. > > See:http://www.radax.com/store.asp?pid=14559 > > Ten speed chains have flared ends and it is the flare that breaks off > when pushed out. This leaves a sharp jagged end that cannot be > reasonably pressed into a chain. The ends of the Shimano Dura Ace > chain is swaged after insertion by forming a dimple in each end. > > Jobst Brandt Flared would be a more accurate description than beveled, my mistake. But my point still stands, that a pin when removed and reinserted results in a weaker link because of damage to the pin "flare". In fact, the instructions that come with Shimano chain warns against reinserting pins. Chris         Date: 27 Jun 2007 09:03:08 From: Peter Cole Subject: Re: Safe to lengthen a chain? Chris Nelson wrote: > On Jun 26, 9:29 pm, jobst.bra...@stanfordalumni.org wrote: >> Chris Nelson writes: >>>>> Both sides are beveled, there is no wrong end. The bevels are bent >>>>> in the direction that would allow the pin to be removed. >>>> From what you write, I suspect you don't know what a bevel is. >>>> There is no way to orient a bevel on the end of a pin. >>>> Again: How is does pushing the pin out destroy the bevel? >>>> As in : "You will see that the end that traveled through the links >>>> has lost its bevel and the end that did not have to travel through >>>> the links has retained its bevel." >>> Push a pin out and look for yourself. Wanna borrow my Park CT-3 ? >> Well, I dropped by the bicycle shop and picked up such a chain and, >> yes, you have your terms mixed up. The pins are flared on both ends, >> not beveled. A bevel at the end of a pin/shaft is a taper used to >> prevent broaching when pressing the circular profile into a round >> hole. >> >> See:http://www.radax.com/store.asp?pid=14559 >> >> Ten speed chains have flared ends and it is the flare that breaks off >> when pushed out. This leaves a sharp jagged end that cannot be >> reasonably pressed into a chain. The ends of the Shimano Dura Ace >> chain is swaged after insertion by forming a dimple in each end. >> >> Jobst Brandt > > Flared would be a more accurate description than beveled, my mistake. Actually, the descriptions are opposite. > > But my point still stands, that a pin when removed and reinserted > results in a weaker link because of damage to the pin "flare". In > fact, the instructions that come with Shimano chain warns against > reinserting pins. Which is why I stopped using Shimano chains years ago. I have not had Sachs 8-speed chains fail after joining with a pin after I discovered how critical it was to make sure the pin protrudes exactly the right amount from the side plates. I have not had a quick link fail, but for one to come undone without damage, it would seem that the only possible way would be to have the link undergo compression. I pulled my daughter for years up steep off-road trails, with her weight up to 90 lb and mine at 230. That, combined with very low gearing and long cranks probably represented chain tensions beyond that which most riders generate.           Date: 27 Jun 2007 17:44:42 From: Sandy Subject: Re: Safe to lengthen a chain? Dans le message de news:fdOdnW_NtMeT_R_bnZ2dnUVZ_gidnZ2d@comcast.com, Peter Cole <peter_cole@comcast.net > a réfléchi, et puis a déclaré : > Chris Nelson wrote: >> On Jun 26, 9:29 pm, jobst.bra...@stanfordalumni.org wrote: >>> Chris Nelson writes: >>>>>> Both sides are beveled, there is no wrong end. The bevels are >>>>>> bent in the direction that would allow the pin to be removed. >>>>> From what you write, I suspect you don't know what a bevel is. >>>>> There is no way to orient a bevel on the end of a pin. >>>>> Again: How is does pushing the pin out destroy the bevel? >>>>> As in : "You will see that the end that traveled through the links >>>>> has lost its bevel and the end that did not have to travel through >>>>> the links has retained its bevel." >>>> Push a pin out and look for yourself. Wanna borrow my Park CT-3 ? >>> Well, I dropped by the bicycle shop and picked up such a chain and, >>> yes, you have your terms mixed up. The pins are flared on both >>> ends, not beveled. A bevel at the end of a pin/shaft is a taper >>> used to prevent broaching when pressing the circular profile into a >>> round hole. >>> >>> See:http://www.radax.com/store.asp?pid=14559 >>> >>> Ten speed chains have flared ends and it is the flare that breaks >>> off when pushed out. This leaves a sharp jagged end that cannot be >>> reasonably pressed into a chain. The ends of the Shimano Dura Ace >>> chain is swaged after insertion by forming a dimple in each end. >>> >>> Jobst Brandt >> >> Flared would be a more accurate description than beveled, my mistake. > > Actually, the descriptions are opposite. It seems to me, that only one end of the pin can be installed "flared", and the other gets peened over after installation, or is there another explanation ? -- Bonne route ! Sandy Verneuil-sur-Seine FR             Date: 28 Jun 2007 09:25:32 From: Peter Cole Subject: Re: Safe to lengthen a chain? Sandy wrote: > Dans le message de news:fdOdnW_NtMeT_R_bnZ2dnUVZ_gidnZ2d@comcast.com, > Peter Cole <peter_cole@comcast.net> a réfléchi, et puis a déclaré : >> Chris Nelson wrote: >>> On Jun 26, 9:29 pm, jobst.bra...@stanfordalumni.org wrote: >>>> Chris Nelson writes: >>>>>>> Both sides are beveled, there is no wrong end. The bevels are >>>>>>> bent in the direction that would allow the pin to be removed. >>>>>> From what you write, I suspect you don't know what a bevel is. >>>>>> There is no way to orient a bevel on the end of a pin. >>>>>> Again: How is does pushing the pin out destroy the bevel? >>>>>> As in : "You will see that the end that traveled through the links >>>>>> has lost its bevel and the end that did not have to travel through >>>>>> the links has retained its bevel." >>>>> Push a pin out and look for yourself. Wanna borrow my Park CT-3 ? >>>> Well, I dropped by the bicycle shop and picked up such a chain and, >>>> yes, you have your terms mixed up. The pins are flared on both >>>> ends, not beveled. A bevel at the end of a pin/shaft is a taper >>>> used to prevent broaching when pressing the circular profile into a >>>> round hole. >>>> >>>> See:http://www.radax.com/store.asp?pid=14559 >>>> >>>> Ten speed chains have flared ends and it is the flare that breaks >>>> off when pushed out. This leaves a sharp jagged end that cannot be >>>> reasonably pressed into a chain. The ends of the Shimano Dura Ace >>>> chain is swaged after insertion by forming a dimple in each end. >>>> >>>> Jobst Brandt >>> Flared would be a more accurate description than beveled, my mistake. >> Actually, the descriptions are opposite. > > It seems to me, that only one end of the pin can be installed "flared", and > the other gets peened over after installation, or is there another > explanation ? I'm not sure I understand your question/context. The only point I was trying to make was that since "bevel" and "flare" mean opposite things the misuse of terms was causing confusion. As to "peening", it seems that all the chains I have seen swage/peen the pin ends on both sides after insertion into the side plates.             Date: 28 Jun 2007 00:51:05 From: Subject: Re: Safe to lengthen a chain? Sandy Leurre writes: >>>>>>> Both sides are beveled, there is no wrong end. The bevels are >>>>>>> bent in the direction that would allow the pin to be removed. >>>>>> From what you write, I suspect you don't know what a bevel is. >>>>>> There is no way to orient a bevel on the end of a pin. Again: >>>>>> How is does pushing the pin out destroy the bevel? As in : >>>>>> "You will see that the end that traveled through the links has >>>>>> lost its bevel and the end that did not have to travel through >>>>>> the links has retained its bevel." >>>>> Push a pin out and look for yourself. >>>>> Wanna borrow my Park CT-3? >>>> Well, I dropped by the bicycle shop and picked up such a chain >>>> and, yes, you have your terms mixed up. The pins are flared on >>>> both ends, not beveled. A bevel at the end of a pin/shaft is a >>>> taper used to prevent broaching when pressing the circular >>>> profile into a round hole. >>>> See: http://www.radax.com/store.asp?pid=14559 >>>> Ten speed chains have flared ends and it is the flare that breaks >>>> off when pushed out. This leaves a sharp jagged end that cannot >>>> be reasonably pressed into a chain. The ends of the Shimano Dura >>>> Ace chain are peened after insertion by forming a dimple in each >>>> end. >>> Flared would be a more accurate description than beveled, my >>> mistake. >> Actually, the descriptions are opposite. > It seems to me, that only one end of the pin can be installed > "flared", and the other gets peened over after installation, or is > there another explanation? The flare appears to be introduced by peening after chain assembly as far as I can tell. Both ends of the pin have a tapered recess to accept a beveled punch for hydraulic compression peening. Jobst Brandt               Date: 29 Jun 2007 21:28:03 From: jim beam Subject: Re: Safe to lengthen a chain? jobst.brandt@stanfordalumni.org wrote: > Sandy Leurre writes: > >>>>>>>> Both sides are beveled, there is no wrong end. The bevels are >>>>>>>> bent in the direction that would allow the pin to be removed. > >>>>>>> From what you write, I suspect you don't know what a bevel is. >>>>>>> There is no way to orient a bevel on the end of a pin. Again: >>>>>>> How is does pushing the pin out destroy the bevel? As in : >>>>>>> "You will see that the end that traveled through the links has >>>>>>> lost its bevel and the end that did not have to travel through >>>>>>> the links has retained its bevel." > >>>>>> Push a pin out and look for yourself. >>>>>> Wanna borrow my Park CT-3? > >>>>> Well, I dropped by the bicycle shop and picked up such a chain >>>>> and, yes, you have your terms mixed up. The pins are flared on >>>>> both ends, not beveled. A bevel at the end of a pin/shaft is a >>>>> taper used to prevent broaching when pressing the circular >>>>> profile into a round hole. > >>>>> See: http://www.radax.com/store.asp?pid=14559 > >>>>> Ten speed chains have flared ends and it is the flare that breaks >>>>> off when pushed out. This leaves a sharp jagged end that cannot >>>>> be reasonably pressed into a chain. The ends of the Shimano Dura >>>>> Ace chain are peened after insertion by forming a dimple in each >>>>> end. > >>>> Flared would be a more accurate description than beveled, my >>>> mistake. > >>> Actually, the descriptions are opposite. > >> It seems to me, that only one end of the pin can be installed >> "flared", and the other gets peened over after installation, or is >> there another explanation? > > The flare appears to be introduced by peening after chain assembly as > far as I can tell. Both ends of the pin have a tapered recess to > accept a beveled punch for hydraulic compression peening. > most modern bike chain is peened in some way. methods vary, but they all achieve the same result - side plate security. "hydraulic" is irrelevant.   Date: 23 Jun 2007 14:57:07 From: Chris Nelson Subject: Re: Safe to lengthen a chain? On Jun 23, 4:32 pm, jobst.bra...@stanfordalumni.org wrote: > Chris Nelson writes: > >> PowerLinks take much power to disengage on a used (dirty) chain. I > >> found that using pliers diagonally, end-to-end of the link, > >> compresses it in both directions enough to open it. That is, if > >> you need to open the chain in the field, as one does if a stick > >> damages the derailleur, a CPR-9 chain tool is the way to do it. > >> You probably cannot get a PowerLink open without tools. > > You can, but it takes a multitude of four letter words strung > > together with rage. The Connex power however, is easy to operate by > > fingers. > > The Connex link is no different from the PowerLink in that it must be > compressed laterally to disengage. What makes you think that a chain > in similar condition to the one that doesn't freely release a > PowerLink will do so for a Connex? > > Jobst Brandt No lateral compression required. See: http://www.connexchain.com/ Click on Products- >Connectors and one of the three Connex link links. There is an animation on how it goes together. Removal goes in reverse. Chris     Date: 23 Jun 2007 23:10:12 From: Subject: Re: Safe to lengthen a chain? Chris Nelson writes: >>>> PowerLinks take much power to disengage on a used (dirty) chain. >>>> I found that using pliers diagonally, end-to-end of the link, >>>> compresses it in both directions enough to open it. That is, if >>>> you need to open the chain in the field, as one does if a stick >>>> damages the derailleur, a CPR-9 chain tool is the way to do it. >>>> You probably cannot get a PowerLink open without tools. >>> You can, but it takes a multitude of four letter words strung >>> together with rage. The Connex power however, is easy to operate >>> by fingers. >> The Connex link is no different from the PowerLink in that it must >> be compressed laterally to disengage. What makes you think that a >> chain in similar condition to the one that doesn't freely release a >> PowerLink will do so for a Connex? > No lateral compression required. > See: http://www.connexchain.com/ > Click on Products->Connectors and one of the three Connex link > links. There is an animation on how it goes together. Removal goes > in reverse. Not exactly. Lateral compression is required to slide the pin out of engagement. The step and re-entrant profile is apparent in the picture. What is simpler is that the two halves of the link are identical, but the method of retention is the same as PowerLink. The design makes use of the lateral angle that these chains require to have a cross-over chain line. When the chain is straight, that little clearance is enough to raise the pis out of the 'lock' slot and into the release hole, which on the Connex is around the corner as it must be for this design. Jobst Brandt       Date: 26 Jun 2007 13:03:48 From: Chris Nelson Subject: Re: Safe to lengthen a chain? On Jun 26, 3:45 pm, jobst.bra...@stanfordalumni.org wrote: > Chris Nelson writes: > >>>>> Modern chain pins are beveled on each side for added strength. > >>>>> Once the pin is pushed through it flattens out the bevel and > >>>>> weakens that link. > >>>> I think you have that backward. 10-speed chain pins have no bevel > >>>> and are flush with the side plate. When pushed in, the original > >>>> pin broaches a larger hole in the side plate so it has no suitable > >>>> press fit and can disengage. The damage is not apparent because > >>>> the other end of the pin still has a press fit and masks the loose > >>>> fit in the re-engaged side plate. > >>>> It is not that any part of the chain breaks (weakens that link) but > >>>> that the side plate bends outward losing support from its pin. > >>> Pop a pin out of a scrap chain and examine it closely (A microscope > >>> would be preferable). You will see that the end that traveled > >>> through the links has lost its bevel and the end that did not have > >>> to travel through the links has retained its bevel. > >> So what causes chain failure with reused pins and where does the bevel > >> go when pressed out? Besides, I suspect you are pushing the wrong end > >> of the pin out. You should press on the beveled end, but even that > >> does not guarantee not broaching the hole on reinsertion. > >> - Show quoted text - > > What means "- Show quoted text -" and who inserts this? > > > Both sides are beveled, there is no wrong end. The bevels are bent in > > the direction that would allow the pin to be removed. > > From what you write, I suspect you don't know what a bevel is. There > is no way to orient a bevel on the end of a pin. > > Again: How is does pushing the pin out destroy the bevel? > > As in : "You will see that the end that traveled through the links has > lost its bevel and the end that did not have to travel through the > links has retained its bevel." > > Jobst Brandt- Hide quoted text - > > - Show quoted text - Push a pin out and look for yourself. Wanna borrow my Park CT-3 ? Chris         Date: 27 Jun 2007 01:34:19 From: Subject: Re: Safe to lengthen a chain? Chris Nelson writes: >>> Both sides are beveled, there is no wrong end. The bevels are bent >>> in the direction that would allow the pin to be removed. >> From what you write, I suspect you don't know what a bevel is. >> There is no way to orient a bevel on the end of a pin. >> Again: How is does pushing the pin out destroy the bevel? >> As in : "You will see that the end that traveled through the links >> has lost its bevel and the end that did not have to travel through >> the links has retained its bevel." > Push a pin out and look for yourself. Wanna borrow my Park CT-3 ? Well, I dropped by the bicycle shop and picked up such a chain and, yes, you have your terms mixed up. The pins are flared on both ends, not beveled. A bevel at the end of a pin/shaft is a taper used to prevent broaching when pressing the circular profile into a round hole. See: http://www.radax.com/store.asp?pid=14559 Ten speed chains have flared ends and it is the flare that breaks off when pushed out. This leaves a sharp jagged end that cannot be reasonably pressed into a chain. The ends of the Shimano Dura Ace chain are peened after insertion, forming a dimple in each end. Jobst Brandt         Date: 27 Jun 2007 01:29:09 From: Subject: Re: Safe to lengthen a chain? Chris Nelson writes: >>> Both sides are beveled, there is no wrong end. The bevels are bent >>> in the direction that would allow the pin to be removed. >> From what you write, I suspect you don't know what a bevel is. >> There is no way to orient a bevel on the end of a pin. >> Again: How is does pushing the pin out destroy the bevel? >> As in : "You will see that the end that traveled through the links >> has lost its bevel and the end that did not have to travel through >> the links has retained its bevel." > Push a pin out and look for yourself. Wanna borrow my Park CT-3 ? Well, I dropped by the bicycle shop and picked up such a chain and, yes, you have your terms mixed up. The pins are flared on both ends, not beveled. A bevel at the end of a pin/shaft is a taper used to prevent broaching when pressing the circular profile into a round hole. See: http://www.radax.com/store.asp?pid=14559 Ten speed chains have flared ends and it is the flare that breaks off when pushed out. This leaves a sharp jagged end that cannot be reasonably pressed into a chain. The ends of the Shimano Dura Ace chain is swaged after insertion by forming a dimple in each end. Jobst Brandt   Date: 23 Jun 2007 13:06:35 From: Chris Nelson Subject: Re: Safe to lengthen a chain? On Jun 23, 3:36 pm, jobst.bra...@stanfordalumni.org wrote: > You probably cannot get a PowerLink open without tools. > > Jobst Brandt You can, but it takes a multitude of four letter words strung together with rage. The Connex power however, is easy to operate by fingers. Chris     Date: 24 Jun 2007 09:05:22 From: andresmuro@aol.com Subject: Re: Safe to lengthen a chain? On Jun 24, 7:02 am, still me <wheeled...@yahoo.com > wrote: > On Sun, 24 Jun 2007 03:36:13 -0700, Chris Nelson > > <smilin...@hotmail.com> wrote: > > >Yes, its fairly safe. The worst that could happen is the pin pops back > >out while riding and the chain falls off. > > Well, I would think that would not be safe if it happened at the wrong > moment :-) > > > Bring an extra connex link > >with you on the ride to repair. if you do it correctly, it won't happen. I've done all kinds of shit to 8 speed chains. They've never broke on me. Andres     Date: 23 Jun 2007 20:32:16 From: Subject: Re: Safe to lengthen a chain? Chris Nelson writes: >> PowerLinks take much power to disengage on a used (dirty) chain. I >> found that using pliers diagonally, end-to-end of the link, >> compresses it in both directions enough to open it. That is, if >> you need to open the chain in the field, as one does if a stick >> damages the derailleur, a CPR-9 chain tool is the way to do it. >> You probably cannot get a PowerLink open without tools. > You can, but it takes a multitude of four letter words strung > together with rage. The Connex power however, is easy to operate by > fingers. The Connex link is no different from the PowerLink in that it must be compressed laterally to disengage. What makes you think that a chain in similar condition to the one that doesn't freely release a PowerLink will do so for a Connex? Jobst Brandt       Date: 26 Jun 2007 21:52:08 From: Johnny Sunset Subject: Re: Safe to lengthen a chain? On Jun 26, 8:07 pm, Jobst Brandt wrote: > Bill Bushnell writes: > >>> Modern chain pins are beveled on each side for added strength. Once > >>> the pin is pushed through it flattens out the bevel and weakens that > >>> link. > >> I think you have that backward. 10-speed chain pins have no bevel and > >> are flush with the side plate. When pushed in, the original pin > >> broaches a larger hole in the side plate so it has no suitable press > >> fit and can disengage. The damage is not apparent because the other > >> end of the pin still has a press fit and masks the loose fit in the > >> re-engaged side plate. > >> It is not that any part of the chain breaks (weakens that link) but > >> that the side plate bends outward losing support from its pin. > > For many years I used cheap Hyperglide 9-speed chains (HG53, HG73) > > and was too cheap to use special $5 pins when connecting them. > > Early on I occasionally broke and bent links: > >http://tinyurl.com/2353aj > > This failure mode became much less frequent after I added a step to > > smash between two hammers the ends of a re-inserted pin so that the > > ends of the pin flared to cover the gap between the link and the > > pin. While it wasn't as sturdy as the original press fit, I found > > it reliable enough on a bike I never rode standing. > > Since the strength of the flare from pin-smashing is variable, I > > wouldn't recommend the technique for a bike that is ridden standing > > due to the risk of severe injury. All of my prior failures had > > occurred while shifting when the chain was under high tension (low > > speed, low gear), where chain failure was inconvenient but not > > injurious. > > I have since switched to KMC and SRAM chains and now have a > > collection of quick links that I'm not too stingy to use. > > You're cheating. There is no way you can go over the bars of fall off > your recumbent from a chain separation. We old fashioned upright > bicycle riders cannot take that risk. That is why I will continue to use the same 8-speed HG chain that I have reinserted the pins in several times until it wears out [1]. [1] Fortunately, it appears that chain life is proportional to the number of links. -- Tom Sherman - Holstein-Friesland Bovinia The weather is here, wish you were beautiful       Date: 26 Jun 2007 14:30:45 From: Jay Beattie Subject: Re: Safe to lengthen a chain? On Jun 26, 11:10 am, "Sandy" <leu...@frree.fr > wrote: > Dans le message denews:46814ed8$0$14120$742ec2ed@news.sonic.net, > jobst.bra...@stanfordalumni.org <jobst.bra...@stanfordalumni.org> a > r=E9fl=E9chi, et puis a d=E9clar=E9 : > > > > > > > Andrew Muzi writes: > > >>> Am I missing something? What is all the hand-wringing about using > >>> a chain tool on a SRAM 8 or 9sp chain? I almost always use chain > >>> tools on my 8 and 9sp chains (Park shop tool). The only chains I > >>> have broken in the last 20 years were at a "power link." I think > >>> these links can bend or disengage when shifted under load under > >>> certain circumstances (that I have not figured out yet). I still > >>> use power links occasionally, but for the most part, I just use a > >>> chain tool. Also, on a really dirty chain (generally speaking, all > >>> my chains), I can remove the chain with a tool before I can even > >>> locate the power link -- let alone wrestle it into submission. > >>> Now, lengthening an old chain with new links may or may not work > >>> depending on the pin wear on the chain. Give it a whirl, see if it > >>> works, and if it doesn't, get a new chain. > > >> As in all things cycling there are many paths, many opinions. My > >> snap link is a different color - easy to spot. I believe most are > >> tinted differently from the other links. > > > That's odd. My chain is entirely black except on the running surface > > of its shiny rollers, regardless of the original color. You must mean > > the color of a link is discernible after steam cleaning. > > > I'm with Jay on this, having used a chain tool since I started > > derailleur bicycling some years ago. My SRAM chains have pins that > > protrude 0.3mm on either side of the link. After pushing the pin into > > the chain, with a trained thumb and forefinger, I can feel when the > > pin is centered and that's as far as I worry about it. I haven't had > > a chain separate in use except the time I used a PowerLink. > > >http://pardo.net/bike/pic/fail-004/000.html > > > Jobst Brandt > > As usual speaking out of ignorance, i.e., being inside 6 and 7 speed > technology. In the future (there is one, and we are already there) chains > are dominantly 8, or more likely 9 and 10 speed widths. > > It also doesn't take much to see your connection link, if you squirt your > water bottle on the chain and clean the chain with some leaves. Yes, tha= t's > primitive, and effective.- Hide quoted text - I challenge you to a duel! We shall place our bikes (9sp chains) against the wall in a dimly lit garage, at night after riding in the rain on dirty roads. A common scenario for me six months of the year. We can even use my dimly lit garage. We shall stand ten paces from our bikes (watch out for the lawnmower) -- me with my Park chain tool, and you with your franco-fingers. A neutral third person will shout "go" and time us as we remove our chains. I guaranty you that I will have my chain off first. I would put 20 Euros on it. Now, I confess, reassembly after a thorough cleaning is a little more fussy for me -- but probably not by more than about 45 seconds, and by then I am in dry clothes and don't care. -- Jay Beattie.       Date: 26 Jun 2007 12:40:32 From: Chris Nelson Subject: Re: Safe to lengthen a chain? On Jun 26, 3:13 pm, jobst.bra...@stanfordalumni.org wrote: > Chris Nelson writes: > >>> Modern chain pins are beveled on each side for added strength. > >>> Once the pin is pushed through it flattens out the bevel and > >>> weakens that link. > >> I think you have that backward. 10-speed chain pins have no bevel > >> and are flush with the side plate. When pushed in, the original > >> pin broaches a larger hole in the side plate so it has no suitable > >> press fit and can disengage. The damage is not apparent because > >> the other end of the pin still has a press fit and masks the loose > >> fit in the re-engaged side plate. > >> It is not that any part of the chain breaks (weakens that link) but > >> that the side plate bends outward losing support from its pin. > > Pop a pin out of a scrap chain and examine it closely (A microscope > > would be preferable). You will see that the end that traveled > > through the links has lost its bevel and the end that did not have > > to travel through the links has retained its bevel. > > So what causes chain failure with reused pins and where does the bevel > go when pressed out? Besides, I suspect you are pushing the wrong end > of the pin out. You should press on the beveled end, but even that > does not guarantee not broaching the hole on reinsertion. > > Jobst Brandt- Hide quoted text - > > - Show quoted text - Both sides are beveled, there is no wrong end. The bevels are bent in the direction that would allow the pin to be removed. Chris         Date: 26 Jun 2007 19:45:51 From: Subject: Re: Safe to lengthen a chain? Chris Nelson writes: >>>>> Modern chain pins are beveled on each side for added strength. >>>>> Once the pin is pushed through it flattens out the bevel and >>>>> weakens that link. >>>> I think you have that backward. 10-speed chain pins have no bevel >>>> and are flush with the side plate. When pushed in, the original >>>> pin broaches a larger hole in the side plate so it has no suitable >>>> press fit and can disengage. The damage is not apparent because >>>> the other end of the pin still has a press fit and masks the loose >>>> fit in the re-engaged side plate. >>>> It is not that any part of the chain breaks (weakens that link) but >>>> that the side plate bends outward losing support from its pin. >>> Pop a pin out of a scrap chain and examine it closely (A microscope >>> would be preferable). You will see that the end that traveled >>> through the links has lost its bevel and the end that did not have >>> to travel through the links has retained its bevel. >> So what causes chain failure with reused pins and where does the bevel >> go when pressed out? Besides, I suspect you are pushing the wrong end >> of the pin out. You should press on the beveled end, but even that >> does not guarantee not broaching the hole on reinsertion. >> - Show quoted text - What means "- Show quoted text -" and who inserts this? > Both sides are beveled, there is no wrong end. The bevels are bent in > the direction that would allow the pin to be removed. From what you write, I suspect you don't know what a bevel is. There is no way to orient a bevel on the end of a pin. Again: How is does pushing the pin out destroy the bevel? As in : "You will see that the end that traveled through the links has lost its bevel and the end that did not have to travel through the links has retained its bevel." Jobst Brandt           Date: 26 Jun 2007 13:57:58 From: Subject: Re: Safe to lengthen a chain? On 26 Jun 2007 19:45:51 GMT, jobst.brandt@stanfordalumni.org wrote: >Chris Nelson writes: [snip] >>> - Show quoted text - > >What means "- Show quoted text -" and who inserts this? [snip] Dear Jobst, If you post through Google Groups, the phrase is inserted when your post includes quoted material from previous posts. When you view a thread in Google Groups, the phrase is highlighted in many posts. (But not if you force a view of a single post.) Clicking on "Show quoted text" in Google Groups will toggle showing or hiding the quoted text of previous posts. The idea is to limit the browsing view to new material. Browse down here to see how it works: http://groups.google.com/group/rec.bicycles.tech/browse_thread/thread/ce106559f75a71f3?tvc=2 Cheers, Carl Fogel             Date: 26 Jun 2007 20:06:43 From: Subject: Re: Safe to lengthen a chain? Carl Fogel writes: > [snip] >>> - Show quoted text - >> What means "- Show quoted text -" and who inserts this? > [snip] > If you post through Google Groups, the phrase is inserted when your > post includes quoted material from previous posts. > When you view a thread in Google Groups, the phrase is highlighted > in many posts. (But not if you force a view of a single post.) > Clicking on "Show quoted text" in Google Groups will toggle showing > or hiding the quoted text of previous posts. > The idea is to limit the browsing view to new material. > Browse down here to see how it works: > http://groups.google.com/group/rec.bicycles.tech/browse_thread/thread/ce106559f75a71f3?tvc=2 Thanks. That doesn't excuse Google for inserting that into the exchange. I don't care if they offer that feature but don't mess with the discourse. Jobst Brandt       Date: 26 Jun 2007 12:08:29 From: Chris Nelson Subject: Re: Safe to lengthen a chain? On Jun 26, 2:31 pm, jobst.bra...@stanfordalumni.org wrote: > Chris Nelson writes: > > Modern chain pins are beveled on each side for added strength. Once > > the pin is pushed through it flattens out the bevel and weakens that > > link. > > I think you have that backward. 10-speed chain pins have no bevel and > are flush with the side plate. When pushed in, the original pin > broaches a larger hole in the side plate so it has no suitable press > fit and can disengage. The damage is not apparent because the other > end of the pin still has a press fit and masks the loose fit in the > re-engaged side plate. > > It is not that any part of the chain breaks (weakens that link) but > that the side plate bends outward losing support from its pin. > > Jobst Brandt Pop a pin out of a scrap chain and examine it closely (A microscope would be preferable). You will see that the end that traveled through the links has lost its bevel and the end that did not have to travel through the links has retained its bevel. Chris         Date: 27 Jun 2007 21:59:41 From: Patrick Lamb Subject: Re: Safe to lengthen a chain? On Tue, 26 Jun 2007 12:08:29 -0700, Chris Nelson <smilin321@hotmail.com > wrote: >On Jun 26, 2:31 pm, jobst.bra...@stanfordalumni.org wrote: >> Chris Nelson writes: >> > Modern chain pins are beveled on each side for added strength. Once >> > the pin is pushed through it flattens out the bevel and weakens that >> > link. >> >> I think you have that backward. 10-speed chain pins have no bevel and >> are flush with the side plate. When pushed in, the original pin >> broaches a larger hole in the side plate so it has no suitable press >> fit and can disengage. The damage is not apparent because the other >> end of the pin still has a press fit and masks the loose fit in the >> re-engaged side plate. >> >> It is not that any part of the chain breaks (weakens that link) but >> that the side plate bends outward losing support from its pin. >> >> Jobst Brandt > >Pop a pin out of a scrap chain and examine it closely (A microscope >would be preferable). You will see that the end that traveled through >the links has lost its bevel and the end that did not have to travel >through the links has retained its bevel. > >Chris Are you confusing "bevel" with "peened end?" Pat Email address works as is.         Date: 26 Jun 2007 19:13:57 From: Subject: Re: Safe to lengthen a chain? Chris Nelson writes: >>> Modern chain pins are beveled on each side for added strength. >>> Once the pin is pushed through it flattens out the bevel and >>> weakens that link. >> I think you have that backward. 10-speed chain pins have no bevel >> and are flush with the side plate. When pushed in, the original >> pin broaches a larger hole in the side plate so it has no suitable >> press fit and can disengage. The damage is not apparent because >> the other end of the pin still has a press fit and masks the loose >> fit in the re-engaged side plate. >> It is not that any part of the chain breaks (weakens that link) but >> that the side plate bends outward losing support from its pin. > Pop a pin out of a scrap chain and examine it closely (A microscope > would be preferable). You will see that the end that traveled > through the links has lost its bevel and the end that did not have > to travel through the links has retained its bevel. So what causes chain failure with reused pins and where does the bevel go when pressed out? Besides, I suspect you are pushing the wrong end of the pin out. You should press on the beveled end, but even that does not guarantee not broaching the hole on reinsertion. Jobst Brandt       Date: 26 Jun 2007 11:08:57 From: Chris Nelson Subject: Re: Safe to lengthen a chain? On Jun 26, 12:51 pm, Jay Beattie <jbeat...@lindsayhart.com > wrote: > On Jun 26, 9:11 am, "Tom Nakashima" <t...@slac.stanford.edu> wrote: > > > > > > > "Jay Beattie" <jbeat...@lindsayhart.com> wrote in message > > >news:1182872316.757102.191630@z28g2000prd.googlegroups.com... > > > > Am I missing something? What is all the hand-wringing about using a > > > chain tool on a SRAM 8 or 9sp chain? I almost always use chain tools > > > on my 8 and 9sp chains (Park shop tool). The only chains I have > > > broken in the last 20 years were at a "power link." I think these > > > links can bend or disengage when shifted under load under certain > > > circumstances (that I have not figured out yet). I still use power > > > links occaisionally, but for the most part, I just use a chain tool. > > > Also, on a really dirty chain (generally speaking, all my chains), I > > > can remove the chain with a tool before I can even locate the power > > > link -- let alone wrestle it into submission. Now, lengthening an old > > > chain with new links may or may not work depending on the pin wear on > > > the chain. Give it a whirl, see if it works, and if it doesn't, get a > > > new chain. -- Jay Beattie. > > > So what do you mean by wrestle it into submission? > > Power links are exceptionally hard to get open on dirty chains. I > know about the magical techniques to get these things open. I can > still break a chain with a tool in about a tenth of the time it takes > to find and open a dirty power link. If Muzzi and those guys are using > chain tools and having 8/9sp chains break, then I will re-think my > approach. But based on my experience, using a chain tool is entirely > safe, assuming some care is given to the process. It has also been my > experience that if you traumatically break a chain (which I have done > in the pre-power link days), you pop a side plate and get grinding > before the chain gives way entirely. I have never had one just break > -- although it may happen, and I defer tothose who claim it has. -- > Jay Beattie.- Hide quoted text - > > - Show quoted text - Modern chain pins are beveled on each side for added strength. Once the pin is pushed through it flattens out the bevel and weakens that link. Chris         Date: 26 Jun 2007 18:31:54 From: Subject: Re: Safe to lengthen a chain? Chris Nelson writes: > Modern chain pins are beveled on each side for added strength. Once > the pin is pushed through it flattens out the bevel and weakens that > link. I think you have that backward. 10-speed chain pins have no bevel and are flush with the side plate. When pushed in, the original pin broaches a larger hole in the side plate so it has no suitable press fit and can disengage. The damage is not apparent because the other end of the pin still has a press fit and masks the loose fit in the re-engaged side plate. It is not that any part of the chain breaks (weakens that link) but that the side plate bends outward losing support from its pin. Jobst Brandt           Date: 26 Jun 2007 22:10:38 From: Bill Bushnell Subject: Re: Safe to lengthen a chain? jobst.brandt@stanfordalumni.org wrote: > Chris Nelson writes: > > Modern chain pins are beveled on each side for added strength. Once > > the pin is pushed through it flattens out the bevel and weakens that > > link. > I think you have that backward. 10-speed chain pins have no bevel and > are flush with the side plate. When pushed in, the original pin > broaches a larger hole in the side plate so it has no suitable press > fit and can disengage. The damage is not apparent because the other > end of the pin still has a press fit and masks the loose fit in the > re-engaged side plate. > It is not that any part of the chain breaks (weakens that link) but > that the side plate bends outward losing support from its pin. For many years I used cheap Hyperglide 9-speed chains (HG53, HG73) and was too cheap to use special $5 pins when connecting them. Early on I occasionally broke and bent links: http://tinyurl.com/2353aj This failure mode became much less frequent after I added a step to smash between two hammers the ends of a re-inserted pin so that the ends of the pin flared to cover the gap between the link and the pin. While it wasn't as sturdy as the original press fit, I found it reliable enough on a bike I never rode standing. Since the strength of the flare from pin-smashing is variable, I wouldn't recommend the technique for a bike that is ridden standing due to the risk of severe injury. All of my prior failures had occurred while shifting when the chain was under high tension (low speed, low gear), where chain failure was inconvenient but not injurious. I have since switched to KMC and SRAM chains and now have a collection of quick links that I'm not too stingy to use. -- Bill Bushnell http://pobox.com/~bushnell/             Date: 27 Jun 2007 01:07:32 From: Subject: Re: Safe to lengthen a chain? Bill Bushnell writes: >>> Modern chain pins are beveled on each side for added strength. Once >>> the pin is pushed through it flattens out the bevel and weakens that >>> link. >> I think you have that backward. 10-speed chain pins have no bevel and >> are flush with the side plate. When pushed in, the original pin >> broaches a larger hole in the side plate so it has no suitable press >> fit and can disengage. The damage is not apparent because the other >> end of the pin still has a press fit and masks the loose fit in the >> re-engaged side plate. >> It is not that any part of the chain breaks (weakens that link) but >> that the side plate bends outward losing support from its pin. > For many years I used cheap Hyperglide 9-speed chains (HG53, HG73) > and was too cheap to use special $5 pins when connecting them. > Early on I occasionally broke and bent links: > http://tinyurl.com/2353aj > This failure mode became much less frequent after I added a step to > smash between two hammers the ends of a re-inserted pin so that the > ends of the pin flared to cover the gap between the link and the > pin. While it wasn't as sturdy as the original press fit, I found > it reliable enough on a bike I never rode standing. > Since the strength of the flare from pin-smashing is variable, I > wouldn't recommend the technique for a bike that is ridden standing > due to the risk of severe injury. All of my prior failures had > occurred while shifting when the chain was under high tension (low > speed, low gear), where chain failure was inconvenient but not > injurious. > I have since switched to KMC and SRAM chains and now have a > collection of quick links that I'm not too stingy to use. You're cheating. There is no way you can go over the bars of fall off your recumbent from a chain separation. We old fashioned upright bicycle riders cannot take that risk. Jobst Brandt               Date: 27 Jun 2007 21:03:02 From: Bill Bushnell Subject: Re: Safe to lengthen a chain? jobst.brandt@stanfordalumni.org wrote: > There is no way you can go over the bars o[r] fall off your recumbent from a > chain separation. http://tinyurl.com/26epwr While this incident did not occur from chain separation, it's not hard to visualize a long wheelbase bike moving at high speed on a rough road how a chain with a suddenly free end could find itself wrapped around a rear wheel leading to lock-up and a possible crash. -- Bill Bushnell http://pobox.com/~bushnell/                 Date: 27 Jun 2007 18:57:48 From: Bob Flumere Subject: Re: Safe to lengthen a chain? I had a KMC master link fall apart on a missed front shift.. the chain fell out of the bike and was run over by the following bicyclist.. We couldn't find one of the pieces to put the monkey link back together, so we pushed a couple of pins and rode home short chained.. End of SRAM chains for this bike.. went back to Shi-mano.. Can't "fall" apart from angular mis-alignment anyway. Bob               Date: 26 Jun 2007 20:32:38 From: Subject: Re: Safe to lengthen a chain? On 27 Jun 2007 01:07:32 GMT, jobst.brandt@stanfordalumni.org wrote: >Bill Bushnell writes: > >>>> Modern chain pins are beveled on each side for added strength. Once >>>> the pin is pushed through it flattens out the bevel and weakens that >>>> link. > >>> I think you have that backward. 10-speed chain pins have no bevel and >>> are flush with the side plate. When pushed in, the original pin >>> broaches a larger hole in the side plate so it has no suitable press >>> fit and can disengage. The damage is not apparent because the other >>> end of the pin still has a press fit and masks the loose fit in the >>> re-engaged side plate. > >>> It is not that any part of the chain breaks (weakens that link) but >>> that the side plate bends outward losing support from its pin. > >> For many years I used cheap Hyperglide 9-speed chains (HG53, HG73) >> and was too cheap to use special $5 pins when connecting them. >> Early on I occasionally broke and bent links: > >> http://tinyurl.com/2353aj > >> This failure mode became much less frequent after I added a step to >> smash between two hammers the ends of a re-inserted pin so that the >> ends of the pin flared to cover the gap between the link and the >> pin. While it wasn't as sturdy as the original press fit, I found >> it reliable enough on a bike I never rode standing. > >> Since the strength of the flare from pin-smashing is variable, I >> wouldn't recommend the technique for a bike that is ridden standing >> due to the risk of severe injury. All of my prior failures had >> occurred while shifting when the chain was under high tension (low >> speed, low gear), where chain failure was inconvenient but not >> injurious. > >> I have since switched to KMC and SRAM chains and now have a >> collection of quick links that I'm not too stingy to use. > >You're cheating. There is no way you can go over the bars of fall off >your recumbent from a chain separation. We old fashioned upright >bicycle riders cannot take that risk. > >Jobst Brandt Dear Jobst, Unfortunately, low-profile recumbents may actually face more dangers. If a low-profile recumbent rider isn't using clipless pedals or if he accidentally twists out of them when a chain breaks, the result can be a very bad crash in which his foot plants, his knee bends back under him like a limbo dancer doing 20 mph or more, and his leg is jammed under his bike and body. The results can include a dislocated hip, mangled knee, and all sorts of other massive damage from toe to hip. And that's just what happens as the rider and bike fly up into the air. Landing hurts, too. Cheers, Carl Fogel                 Date: 27 Jun 2007 03:06:26 From: Subject: Re: Safe to lengthen a chain? Carl Fogel writes: > Unfortunately, low-profile recumbents may actually face more > dangers. > If a low-profile recumbent rider isn't using clipless pedals or if > he accidentally twists out of them when a chain breaks, the result > can be a very bad crash in which his foot plants, his knee bends > back under him like a limbo dancer doing 20 mph or more, and his leg > is jammed under his bike and body. > The results can include a dislocated hip, mangled knee, and all > sorts of other massive damage from toe to hip. > And that's just what happens as the rider and bike fly up into the > air. > Landing hurts, too. I'll leave that part of the scenario to Bill Bushnell to explain. You assume the rider is not attached to his pedals, which Bill is and you assume he would limply let his foot fall under the bicycle. If you go that far, you can describe worse scenarios for upright bicycles that are bad enough already. I've tried them. Jobst Brandt                   Date: 27 Jun 2007 21:35:10 From: Bill Bushnell Subject: Re: Safe to lengthen a chain? jobst.brandt@stanfordalumni.org wrote: > I'll leave that part of the scenario to Bill Bushnell to explain. You > assume the rider is not attached to his pedals, which Bill is and you > assume he would limply let his foot fall under the bicycle. If you go > that far, you can describe worse scenarios for upright bicycles that > are bad enough already. I've tried them. A sudden chain break (or crank failure or most likely, clip disengagement) on a recumbent sends the foot flying forward, usually harmlessly. On any bike with a low seat there is the hazard of putting a foot down while the bike is in motion. If the shoe gains ground traction (doesn't slide), then the leg can be pulled back and under the seat, resulting in a crash and often a broken leg with a spiral fracture. An acquaintance of mine seemed to be particularly prone to this. As I see it the danger is greatest when riding at moderate speed or faster on loose or uncertain surfaces where I might be tempted to keep a foot loose on the pedal for an occasional foot-dab. During all of my on-road low-side crashes (all of them on damp and dirty roads where traction is hard to assess) I have ridden the bike down with feet in clips... after desperately trying to right the situation. -- Bill Bushnell http://pobox.com/~bushnell/                   Date: 26 Jun 2007 21:18:35 From: Subject: Re: Safe to lengthen a chain? On 27 Jun 2007 03:06:26 GMT, jobst.brandt@stanfordalumni.org wrote: >Carl Fogel writes: > >> Unfortunately, low-profile recumbents may actually face more >> dangers. > >> If a low-profile recumbent rider isn't using clipless pedals or if >> he accidentally twists out of them when a chain breaks, the result >> can be a very bad crash in which his foot plants, his knee bends >> back under him like a limbo dancer doing 20 mph or more, and his leg >> is jammed under his bike and body. > >> The results can include a dislocated hip, mangled knee, and all >> sorts of other massive damage from toe to hip. > >> And that's just what happens as the rider and bike fly up into the >> air. > >> Landing hurts, too. > You assume the rider is not attached to his pedals . . . [snip] >Jobst Brandt Dear Jobst, No, I didn't. "If a low-profile recumbent rider isn't using clipless pedals or if he accidentally twists out of them when a chain breaks . . ." Cheers, Carl Fogel         Date: 26 Jun 2007 18:28:56 From: Subject: Re: Safe to lengthen a chain? Chris Nelson writes: > Modern chain pins are beveled on each side for added strength. Once > the pin is pushed through it flattens out the bevel and weakens that > link. I think you have that backward. 10-speed chain pins have no bevel and are flush with the side plate. When pushed in, the pin original broaches a larger hole in the side plate so it has no suitable press fit and can disengage. The damage is not apparent because the other end of the pin still has a press fit and masks the loose fit in the re-engaged side plate. It is not that any part of the chain breaks (weakens that link) but that the side plate bends outward losing support from its pin. Jobst Brandt       Date: 26 Jun 2007 09:51:48 From: Jay Beattie Subject: Re: Safe to lengthen a chain? On Jun 26, 9:11 am, "Tom Nakashima" <t...@slac.stanford.edu > wrote: > "Jay Beattie" <jbeat...@lindsayhart.com> wrote in message > > news:1182872316.757102.191630@z28g2000prd.googlegroups.com... > > > Am I missing something? What is all the hand-wringing about using a > > chain tool on a SRAM 8 or 9sp chain? I almost always use chain tools > > on my 8 and 9sp chains (Park shop tool). The only chains I have > > broken in the last 20 years were at a "power link." I think these > > links can bend or disengage when shifted under load under certain > > circumstances (that I have not figured out yet). I still use power > > links occaisionally, but for the most part, I just use a chain tool. > > Also, on a really dirty chain (generally speaking, all my chains), I > > can remove the chain with a tool before I can even locate the power > > link -- let alone wrestle it into submission. Now, lengthening an old > > chain with new links may or may not work depending on the pin wear on > > the chain. Give it a whirl, see if it works, and if it doesn't, get a > > new chain. -- Jay Beattie. > > So what do you mean by wrestle it into submission? Power links are exceptionally hard to get open on dirty chains. I know about the magical techniques to get these things open. I can still break a chain with a tool in about a tenth of the time it takes to find and open a dirty power link. If Muzzi and those guys are using chain tools and having 8/9sp chains break, then I will re-think my approach. But based on my experience, using a chain tool is entirely safe, assuming some care is given to the process. It has also been my experience that if you traumatically break a chain (which I have done in the pre-power link days), you pop a side plate and get grinding before the chain gives way entirely. I have never had one just break -- although it may happen, and I defer tothose who claim it has. -- Jay Beattie.         Date: 26 Jun 2007 20:30:49 From: A R:nen Subject: Re: Safe to lengthen a chain? Jay Beattie <jbeattie@lindsayhart.com > writes: > Power links are exceptionally hard to get open on dirty chains. At least with my technique of chain non-lubrication (waxing with plain paraffin), the Powerlink becomes noticeably *easier* to open when it has been in use for a while. Even up to the point that I have had one open while coasting (on a path covered with lumpy snow), and since then I have certainly started paying more attention to it and replacing when appropriate.         Date: 26 Jun 2007 10:09:51 From: Tom Nakashima Subject: Re: Safe to lengthen a chain? "Jay Beattie" <jbeattie@lindsayhart.com > wrote in message news:1182876708.236082.24290@e16g2000pri.googlegroups.com... > On Jun 26, 9:11 am, "Tom Nakashima" <t...@slac.stanford.edu> wrote: >> "Jay Beattie" <jbeat...@lindsayhart.com> wrote in message >> >> news:1182872316.757102.191630@z28g2000prd.googlegroups.com... >> >> > Am I missing something? What is all the hand-wringing about using a >> > chain tool on a SRAM 8 or 9sp chain? I almost always use chain tools >> > on my 8 and 9sp chains (Park shop tool). The only chains I have >> > broken in the last 20 years were at a "power link." I think these >> > links can bend or disengage when shifted under load under certain >> > circumstances (that I have not figured out yet). I still use power >> > links occaisionally, but for the most part, I just use a chain tool. >> > Also, on a really dirty chain (generally speaking, all my chains), I >> > can remove the chain with a tool before I can even locate the power >> > link -- let alone wrestle it into submission. Now, lengthening an old >> > chain with new links may or may not work depending on the pin wear on >> > the chain. Give it a whirl, see if it works, and if it doesn't, get a >> > new chain. -- Jay Beattie. >> >> So what do you mean by wrestle it into submission? > > Power links are exceptionally hard to get open on dirty chains. I > know about the magical techniques to get these things open. I can > still break a chain with a tool in about a tenth of the time it takes > to find and open a dirty power link. If Muzzi and those guys are using > chain tools and having 8/9sp chains break, then I will re-think my > approach. But based on my experience, using a chain tool is entirely > safe, assuming some care is given to the process. It has also been my > experience that if you traumatically break a chain (which I have done > in the pre-power link days), you pop a side plate and get grinding > before the chain gives way entirely. I have never had one just break > -- although it may happen, and I defer tothose who claim it has. -- > Jay Beattie. > I've seen cyclist unsuccessfully try to unlink the powerlink while the chain is under tension. Once I locate the PL, I remove the chain off the chainring, so that it's slack. Make the "U" shape and the PL comes apart. I never had one break or disengage while riding. -tom       Date: 26 Jun 2007 08:38:36 From: Jay Beattie Subject: Re: Safe to lengthen a chain? On Jun 26, 7:43 am, still me <wheeled...@yahoo.com > wrote: > On Sun, 24 Jun 2007 19:08:37 -0500, A Muzi <a...@yellowjersey.org> > wrote: > > >To some riders, "The worst that could happen is the pin pops back > >out" could mean serious injury or death. Have you experienced broken a > >chain while standing yourself? > > >It may be interpretive, but "broken chain" and "fairly safe" are not the > >same in my book. > > That would be my concern. I'm good with the chain tool... but I don't > want a chain break. > > On the flip side, I do sometimes need to change chain length when I > change gearing and I don't like the idea of multiple power links in a > chain... or the requirement to have a half dozen "short bits" to make > up the lengths I might need. So, the 'ol chain tool idea is quite > convenient. > > Still, I guess I'm a little confused - even if the new chain starts > out tighter, if it ends up as tight as the 'ol chains, wouldn't the > connection be just as strong as the one we had in the old days? In > other words, it's not as tight as a new 8sp chain, but it's as tight > as the older 5/6 sp chain that was perfectly reliable and never failed Am I missing something? What is all the hand-wringing about using a chain tool on a SRAM 8 or 9sp chain? I almost always use chain tools on my 8 and 9sp chains (Park shop tool). The only chains I have broken in the last 20 years were at a "power link." I think these links can bend or disengage when shifted under load under certain circumstances (that I have not figured out yet). I still use power links occaisionally, but for the most part, I just use a chain tool. Also, on a really dirty chain (generally speaking, all my chains), I can remove the chain with a tool before I can even locate the power link -- let alone wrestle it into submission. Now, lengthening an old chain with new links may or may not work depending on the pin wear on the chain. Give it a whirl, see if it works, and if it doesn't, get a new chain. -- Jay Beattie.         Date: 28 Jun 2007 13:25:26 From: Chris Nelson Subject: Re: Safe to lengthen a chain? On Jun 28, 4:16 pm, Peter Cole <peter_c...@comcast.net > wrote: > FWIW, they don't, as you claim, caution you to use the quick link. Actually, they do, but this caution only applies to the "Hollow Pin" versions. Chris         Date: 26 Jun 2007 12:06:19 From: A Muzi Subject: Re: Safe to lengthen a chain? -snip- >> A Muzi <a...@yellowjersey.org> wrote: >>> To some riders, "The worst that could happen is the pin pops back >>> out" could mean serious injury or death. Have you experienced broken a >>> chain while standing yourself? >>> It may be interpretive, but "broken chain" and "fairly safe" are not the >>> same in my book. > still me <wheeled...@yahoo.com> wrote: >> That would be my concern. I'm good with the chain tool... but I don't >> want a chain break. >> On the flip side, I do sometimes need to change chain length when I >> change gearing and I don't like the idea of multiple power links in a >> chain... or the requirement to have a half dozen "short bits" to make >> up the lengths I might need. So, the 'ol chain tool idea is quite >> convenient. >> Still, I guess I'm a little confused - even if the new chain starts >> out tighter, if it ends up as tight as the 'ol chains, wouldn't the >> connection be just as strong as the one we had in the old days? In >> other words, it's not as tight as a new 8sp chain, but it's as tight >> as the older 5/6 sp chain that was perfectly reliable and never failed Jay Beattie wrote: > Am I missing something? What is all the hand-wringing about using a > chain tool on a SRAM 8 or 9sp chain? I almost always use chain tools > on my 8 and 9sp chains (Park shop tool). The only chains I have > broken in the last 20 years were at a "power link." I think these > links can bend or disengage when shifted under load under certain > circumstances (that I have not figured out yet). I still use power > links occaisionally, but for the most part, I just use a chain tool. > Also, on a really dirty chain (generally speaking, all my chains), I > can remove the chain with a tool before I can even locate the power > link -- let alone wrestle it into submission. Now, lengthening an old > chain with new links may or may not work depending on the pin wear on > the chain. Give it a whirl, see if it works, and if it doesn't, get a > new chain. -- Jay Beattie. As in all things cycling there are many paths, many opinions. My snap link is a different color - easy to spot. I believe most are tinted differently from the other links. -- Andrew Muzi www.yellowjersey.org Open every day since 1 April, 1971           Date: 26 Jun 2007 17:20:30 From: Jay Beattie Subject: Re: Safe to lengthen a chain? On Jun 26, 2:48 pm, carlfo...@comcast.net wrote: > On 26 Jun 2007 19:58:37 GMT, jobst.bra...@stanfordalumni.org wrote: > > > > > > >Carl Fogel writes: > > >>>>>>>>> I haven't had a chain separate in use except the time I used > >>>>>>>>> a PowerLink. > > >>>>>>>> I'm curious, how did your chain separate when you used a > >>>>>>>> PowerLink? > > >>>>>>> That event has been retold here a few times. > > >>>>>>> After installing a new chain on used sprockets, the chain > >>>>>>> skipped occasionally on the 13t sprocket. One of these skips > >>>>>>> occurred at the precise moment before the PowerLink went into > >>>>>>> engagement and the inertia of following links compressed the > >>>>>>> chain enough to separate the link (after I had ridden more than > >>>>>>> 10 miles). > > >>>>>> I haven't heard this before, and can't imagine the PowerLink > >>>>>> disengaging under tension even when rolling over such a small > >>>>>> diameter as a 13t sprocket. Cyclist have used the PowerLink > >>>>>> connector on 12t or even 11t sprockets without failure. The only > >>>>>> way I could possibly see the PowerLink disengaging, would be > >>>>>> backpedaling and having the chain getting hung-up to compress > >>>>>> the PowerLink enough to become disengaged. > > >>>>> Slow down. Re-read the description of PowerLink separation. It > >>>>> did not separate while that part of the chain was in tension! > > >>>> Given gravity, when is any part of a bicycle chain not in at least > >>>> some tension? > > >>> INERTIA! Read the item! As the chain was going into engagement > >>> precisely at the moment the PowerLink approached the 13t sprocket, > >>> the chain skipped. Chain skip accelerates the chain to move > >>> forward in a few milliseconds and stops as the chain falls back > >>> into engagement. Inertia of the following chain compressed the > >>> PowerLink enough to make it fall apart. > > >> I'm still puzzled. > > >> Are you saying that a metal chain constantly slows down as it is > >> _pulled_ onto a gear? > > >Are you reading what I write??? > > >I said I installed a new chain on used sprockets and found that the > >chain skipped on the 13t sprocket as I rode to work. One of those > >skips occurred just as the PowerLink approached engagement with that > >13t sprocket. Chain skip rapidly accelerates the chain (in a couple > >of milliseconds) for the duration of a single link (1/2" to be exact), > >after which it slows to normal chain speed. That deceleration caused > >the following chain, by its inertia, to compress the PowerLink and > >disengage it. > > >With each iteration I'm adding words that seem to make no difference > >to you and Tom. What is missing? > > >... or maybe you are pulling my leg, so to speak. > > >Jobst Brandt > > Dear Jobst, > > Drop the paranoia. > > Tom and I are just curious about what seems to be an odd claim. > > I can't recall anyone else mentioning this problem. Almost eight years ago (count 'em, eight), I made this complaint on this NG: I have made adverse comments about the PC59 because the rollers break and dent under heavy load. I have also broken a PC59 at the "power link." Broken rollers suggest to me that the chain is not tough enough for long, heavy, low-gear touring. But I don't know if any 9 speed chain is better and would probably use an 8 speed transmission in any event. -- Jay Beattie. That was in September, 1999. I made the same complaint in April, 2000: Could both side plates remain on the chain if one of the pins broke at its base? I broke a Powerlink after a rough shift into the inner ring (30t) while climbing a very steep pitch with my son in a Burley trailer. One side plate was bent out about 30 degrees, but, IIRC, the plates fell out of the chain when it broke. -- Jay Beattie. Then again in September, 2002: I am 225 lbs and ride the same chain and also ride up a 30+ % hill to get out of my parking garage every night -- although I do it in a somewhat higher gear. I have never outright snapped a Sachs chain, although I have dented or broken the rollers on a nine speed chain. I have also had failures at the powerlink which were probably caused by chain suck partially opening the link. This is why I quit using powerlinks, among other reasons. There is no epidemic of breaking Sachs chains that I know of, and the poster may have just gotten a rare bad one. -- Jay Beattie. I am happy to announce that I have lost weight since September, 2002, and the hill out of the garage is probably more in the neighborhood of 23% -- but apart from that, the posts are accurate. I never even posted about the broken power link in front of the YMCA while riding on relatively flat ground. I got a ride home from my wife, but still had to scooter for about a mile to meet her. I hate scootering. Anyway, these things can break -- sorry, they can. I am not clear on the mechanism and defer to mechanical engineeers to figure that one out. They don't break a lot, however, and that is the good news. -- Jay Beattie.             Date: 26 Jun 2007 20:20:09 From: Subject: Re: Safe to lengthen a chain? On Tue, 26 Jun 2007 17:20:30 -0700, Jay Beattie <jbeattie@lindsayhart.com > wrote: >On Jun 26, 2:48 pm, carlfo...@comcast.net wrote: >> On 26 Jun 2007 19:58:37 GMT, jobst.bra...@stanfordalumni.org wrote: >> >> >Carl Fogel writes: >> >> >>>>>>>>> I haven't had a chain separate in use except the time I used >> >>>>>>>>> a PowerLink. >> >> >>>>>>>> I'm curious, how did your chain separate when you used a >> >>>>>>>> PowerLink? >> >> >>>>>>> That event has been retold here a few times. >> >> >>>>>>> After installing a new chain on used sprockets, the chain >> >>>>>>> skipped occasionally on the 13t sprocket. One of these skips >> >>>>>>> occurred at the precise moment before the PowerLink went into >> >>>>>>> engagement and the inertia of following links compressed the >> >>>>>>> chain enough to separate the link (after I had ridden more than >> >>>>>>> 10 miles). >> >> >>>>>> I haven't heard this before, and can't imagine the PowerLink >> >>>>>> disengaging under tension even when rolling over such a small >> >>>>>> diameter as a 13t sprocket. Cyclist have used the PowerLink >> >>>>>> connector on 12t or even 11t sprockets without failure. The only >> >>>>>> way I could possibly see the PowerLink disengaging, would be >> >>>>>> backpedaling and having the chain getting hung-up to compress >> >>>>>> the PowerLink enough to become disengaged. >> >> >>>>> Slow down. Re-read the description of PowerLink separation. It >> >>>>> did not separate while that part of the chain was in tension! >> >> >>>> Given gravity, when is any part of a bicycle chain not in at least >> >>>> some tension? >> >> >>> INERTIA! Read the item! As the chain was going into engagement >> >>> precisely at the moment the PowerLink approached the 13t sprocket, >> >>> the chain skipped. Chain skip accelerates the chain to move >> >>> forward in a few milliseconds and stops as the chain falls back >> >>> into engagement. Inertia of the following chain compressed the >> >>> PowerLink enough to make it fall apart. >> >> >> I'm still puzzled. >> >> >> Are you saying that a metal chain constantly slows down as it is >> >> _pulled_ onto a gear? >> >> >Are you reading what I write??? >> >> >I said I installed a new chain on used sprockets and found that the >> >chain skipped on the 13t sprocket as I rode to work. One of those >> >skips occurred just as the PowerLink approached engagement with that >> >13t sprocket. Chain skip rapidly accelerates the chain (in a couple >> >of milliseconds) for the duration of a single link (1/2" to be exact), >> >after which it slows to normal chain speed. That deceleration caused >> >the following chain, by its inertia, to compress the PowerLink and >> >disengage it. >> >> >With each iteration I'm adding words that seem to make no difference >> >to you and Tom. What is missing? >> >> >... or maybe you are pulling my leg, so to speak. >> >> >Jobst Brandt >> >> Dear Jobst, >> >> Drop the paranoia. >> >> Tom and I are just curious about what seems to be an odd claim. >> >> I can't recall anyone else mentioning this problem. > >Almost eight years ago (count 'em, eight), I made this complaint on >this NG: > >I have made adverse comments about the PC59 because the rollers break >and >dent under heavy load. I have also broken a PC59 at the "power >link." >Broken rollers suggest to me that the chain is not tough enough for >long, >heavy, low-gear touring. But I don't know if any 9 speed chain is >better >and would probably use an 8 speed transmission in any event. -- Jay >Beattie. > >That was in September, 1999. I made the same complaint in April, >2000: > >Could both side plates remain on the chain if one >of the pins broke at its base? I broke a Powerlink >after a rough shift into the inner ring (30t) >while climbing a very steep pitch with my son in a >Burley trailer. One side plate was bent out about >30 degrees, but, IIRC, the plates fell out of the >chain when it broke. -- Jay Beattie. > >Then again in September, 2002: > > I am 225 lbs and ride the same chain and also ride up a 30+ % hill >to >get out of my parking garage every night -- although I do it in a >somewhat higher gear. I have never outright snapped a Sachs chain, >although I have dented or broken the rollers on a nine speed chain. I >have also had failures at the powerlink which were probably caused by >chain suck partially opening the link. This is why I quit using >powerlinks, among other reasons. There is no epidemic of breaking >Sachs >chains that I know of, and the poster may have just gotten a rare bad >one. -- Jay Beattie. > >I am happy to announce that I have lost weight since September, 2002, >and the hill out of the garage is probably more in the neighborhood of >23% -- but apart from that, the posts are accurate. I never even >posted about the broken power link in front of the YMCA while riding >on relatively flat ground. I got a ride home from my wife, but still >had to scooter for about a mile to meet her. I hate scootering. > >Anyway, these things can break -- sorry, they can. I am not clear on >the mechanism and defer to mechanical engineeers to figure that one >out. They don't break a lot, however, and that is the good news. -- >Jay Beattie. Dear Jay, If I'm following you . . . You've had several quick-connect failures. Sometimes the link broke or at least bent. Sometimes the link failed with a 225-lb rider and a steep climb. Sometimes the link may have been involved with chain suck. But the chain suck is as close as you came to chain-skipping? I'm not arguing, just checking whether chain-skip was involved. Strange things do happen with chains. I once checked my chain after things felt funny near the end of my daily ride and found a roller missing. Cheers, Carl Fogel           Date: 26 Jun 2007 17:37:28 From: Subject: Re: Safe to lengthen a chain? Andrew Muzi writes: >> Am I missing something? What is all the hand-wringing about using >> a chain tool on a SRAM 8 or 9sp chain? I almost always use chain >> tools on my 8 and 9sp chains (Park shop tool). The only chains I >> have broken in the last 20 years were at a "power link." I think >> these links can bend or disengage when shifted under load under >> certain circumstances (that I have not figured out yet). I still >> use power links occasionally, but for the most part, I just use a >> chain tool. Also, on a really dirty chain (generally speaking, all >> my chains), I can remove the chain with a tool before I can even >> locate the power link -- let alone wrestle it into submission. >> Now, lengthening an old chain with new links may or may not work >> depending on the pin wear on the chain. Give it a whirl, see if it >> works, and if it doesn't, get a new chain. > As in all things cycling there are many paths, many opinions. My > snap link is a different color - easy to spot. I believe most are > tinted differently from the other links. That's odd. My chain is entirely black except on the running surface of its shiny rollers, regardless of the original color. You must mean the color of a link is discernible after steam cleaning. I'm with Jay on this, having used a chain tool since I started derailleur bicycling some years ago. My SRAM chains have pins that protrude 0.3mm on either side of the link. After pushing the pin into the chain, with a trained thumb and forefinger, I can feel when the pin is centered and that's as far as I worry about it. I haven't had a chain separate in use except the time I used a PowerLink. http://pardo.net/bike/pic/fail-004/000.html Jobst Brandt             Date: 26 Jun 2007 20:10:53 From: Sandy Subject: Re: Safe to lengthen a chain? Dans le message de news:46814ed8$0$14120$742ec2ed@news.sonic.net, jobst.brandt@stanfordalumni.org <jobst.brandt@stanfordalumni.org > a réfléchi, et puis a déclaré : > Andrew Muzi writes: > >>> Am I missing something? What is all the hand-wringing about using >>> a chain tool on a SRAM 8 or 9sp chain? I almost always use chain >>> tools on my 8 and 9sp chains (Park shop tool). The only chains I >>> have broken in the last 20 years were at a "power link." I think >>> these links can bend or disengage when shifted under load under >>> certain circumstances (that I have not figured out yet). I still >>> use power links occasionally, but for the most part, I just use a >>> chain tool. Also, on a really dirty chain (generally speaking, all >>> my chains), I can remove the chain with a tool before I can even >>> locate the power link -- let alone wrestle it into submission. >>> Now, lengthening an old chain with new links may or may not work >>> depending on the pin wear on the chain. Give it a whirl, see if it >>> works, and if it doesn't, get a new chain. > >> As in all things cycling there are many paths, many opinions. My >> snap link is a different color - easy to spot. I believe most are >> tinted differently from the other links. > > That's odd. My chain is entirely black except on the running surface > of its shiny rollers, regardless of the original color. You must mean > the color of a link is discernible after steam cleaning. > > I'm with Jay on this, having used a chain tool since I started > derailleur bicycling some years ago. My SRAM chains have pins that > protrude 0.3mm on either side of the link. After pushing the pin into > the chain, with a trained thumb and forefinger, I can feel when the > pin is centered and that's as far as I worry about it. I haven't had > a chain separate in use except the time I used a PowerLink. > > http://pardo.net/bike/pic/fail-004/000.html > > Jobst Brandt As usual speaking out of ignorance, i.e., being inside 6 and 7 speed technology. In the future (there is one, and we are already there) chains are dominantly 8, or more likely 9 and 10 speed widths. It also doesn't take much to see your connection link, if you squirt your water bottle on the chain and clean the chain with some leaves. Yes, that's primitive, and effective.               Date: 27 Jun 2007 20:17:47 From: Jay Beattie Subject: Re: Safe to lengthen a chain? On Jun 27, 5:21 pm, carlfo...@comcast.net wrote: > On Tue, 26 Jun 2007 23:55:30 -0500, A Muzi <a...@yellowjersey.org> > wrote: <big snip > > Several other posters did come forward right away and mentioned > problems with quick-connects. Some of them involved broken and bent > links, but that could be just worse luck after the quick-connect's > initial separation. I'm not sure if anyone else recalled a chain > skipping just before its quick-connect came apart. One skipped, probably because I had broken rollers by climbing in low gears with a trailer/kid in tow. That was an eye opener. I had never broken a chain roller before. The second chain skipped but primarily made a grinding sound for about fifty yards and then broke, IIRC. I thought I was suffering from my usual post-rainstorm lack of lubrication. Both of these chains had hundreds of miles on them, and if the power link were misinstalled, it would have failed immediately. Other people outside this NG have reported failures. I assume the failure rate is far below that associated with using a pin tool to remove and reassemble the chain. Personally, I have never had a chain failure as a result of mis-installing a pin on a 8 or 9sp SRAM/Sedis chain. I confess to screwing up a 5/6sp chain on a fixed gear commuting bike and broke that chain. Long walk to work. That was 22 years ago. I remember because a woman at work made fun of me -- so I married her. -- Jay Beattie.                 Date: 28 Jun 2007 16:16:26 From: still me Subject: Re: Safe to lengthen a chain? On Wed, 27 Jun 2007 20:17:47 -0700, Jay Beattie <jbeattie@lindsayhart.com > wrote: > I remember because a woman at work made fun of me -- so I >married her. -- Jay Beattie. Wow... two severe accidents in one day!                 Date: 27 Jun 2007 21:20:37 From: Subject: Re: Safe to lengthen a chain? On Wed, 27 Jun 2007 20:17:47 -0700, Jay Beattie <jbeattie@lindsayhart.com > wrote: >On Jun 27, 5:21 pm, carlfo...@comcast.net wrote: >> On Tue, 26 Jun 2007 23:55:30 -0500, A Muzi <a...@yellowjersey.org> >> wrote: ><big snip> > >> Several other posters did come forward right away and mentioned >> problems with quick-connects. Some of them involved broken and bent >> links, but that could be just worse luck after the quick-connect's >> initial separation. I'm not sure if anyone else recalled a chain >> skipping just before its quick-connect came apart. > >One skipped, probably because I had broken rollers by climbing in low >gears with a trailer/kid in tow. That was an eye opener. I had never >broken a chain roller before. The second chain skipped but primarily >made a grinding sound for about fifty yards and then broke, IIRC. I >thought I was suffering from my usual post-rainstorm lack of >lubrication. Both of these chains had hundreds of miles on them, and >if the power link were misinstalled, it would have failed immediately. > >Other people outside this NG have reported failures. I assume the >failure rate is far below that associated with using a pin tool to >remove and reassemble the chain. Personally, I have never had a chain >failure as a result of mis-installing a pin on a 8 or 9sp SRAM/Sedis >chain. I confess to screwing up a 5/6sp chain on a fixed gear >commuting bike and broke that chain. Long walk to work. That was 22 >years ago. I remember because a woman at work made fun of me -- so I >married her. -- Jay Beattie. Dear Jay, Serves her right for making fun of you! Er, I mean congratulations. Cheers, Carl Fogel               Date: 28 Jun 2007 01:59:02 From: Subject: Re: Safe to lengthen a chain? > But if a sharp rap does open a quick-connect, I'll have to wonder why > they don't fly apart when riders are jolting down bumpy hills. A > quick-connect just about to enter or leave the front sprocket has the > whole chain run banging it forward to compress things, and it has a > good chance of being in that position during a year's riding. Carl, Stop setting up straw men. You've announced that if what Jobst says is true, then it's also true of a chain that's jolting down bumpy hills or rapped with a hammer. Neither of which imparts to the lower run of chain the uniform and directionally pure momentum that a skipping chain does when it stops skipping. Why have you introduced these vagaries? By doing so, you have removed the critical ingredient, and thus guaranteed that your experiment will fail, producing the results you desire. You yourself have claimed that it is possible to use a rubber band in compression only if it's already in tension. Now you're saying that Jobst is wrong because, as you can prove with a hammer, you can't use a slack chain in compression. Think harder, Homer. -Bart               Date: 26 Jun 2007 11:26:14 From: Tom Nakashima Subject: Re: Safe to lengthen a chain? >>. I haven't had >> a chain separate in use except the time I used a PowerLink. >> >> http://pardo.net/bike/pic/fail-004/000.html >> >> Jobst Brandt > I'm curious, how did your chain separate when you used a PowerLink? -tom                 Date: 26 Jun 2007 18:46:44 From: Subject: Re: Safe to lengthen a chain? Tom Nakashima writes: >> I haven't had a chain separate in use except the time I used a >> PowerLink. > I'm curious, how did your chain separate when you used a PowerLink? That event has been retold here a few times. After installing a new chain on used sprockets, the chain skipped occasionally on the 13t sprocket. One of these skips occurred at the precise moment before the PowerLink went into engagement and the inertia of following links compresses the chain enough to separate the link (after I had ridden more than 10 miles). There being no traffic, I was able to find the two parts of the link on the road, re-engage it and finish riding to work. After that, I didn't get around to getting rid of the link and rode on dusty dirt roads long enough to make it a dirty chain, one that would not readily allow separating the link manually. The link must be compressed laterally the depth of the ledge in the stepped pin hole, essentially most of the lateral clearance in the chain. With fine grit between the plates, the PowerLink cannot be manually released. As I said, I used pliers diagonally across the link to open it. This compresses the link laterally while pushing open. Although this works, as has been mentioned, a PowerLink does not help if you have chain failure. You need a chain tool. Jobst Brandt                   Date: 26 Jun 2007 12:04:37 From: Tom Nakashima Subject: Re: Safe to lengthen a chain? <jobst.brandt@stanfordalumni.org > wrote in message news:46815f14$0$14139$742ec2ed@news.sonic.net... > Tom Nakashima writes: > >>> I haven't had a chain separate in use except the time I used a >>> PowerLink. > >> I'm curious, how did your chain separate when you used a PowerLink? > > That event has been retold here a few times. > > After installing a new chain on used sprockets, the chain skipped > occasionally on the 13t sprocket. One of these skips occurred at the > precise moment before the PowerLink went into engagement and the > inertia of following links compresses the chain enough to separate the > link (after I had ridden more than 10 miles). > Jobst Brandt I haven't heard this before, and can't imagine the PowerLink disengaging under tension even when rolling over such a small diameter as a 13t sprocket. Cyclist have used the PowerLink connector on 12t or even 11t sprockets without failure. The only way I could possibly see the PowerLink disengaging, would be backpedaling and having the chain getting hung-up to compress the PowerLink enough to become disengaged. -tom                     Date: 26 Jun 2007 19:17:45 From: Subject: Re: Safe to lengthen a chain? Tom Nakashima writes: >>>> I haven't had a chain separate in use except the time I used a >>>> PowerLink. >>> I'm curious, how did your chain separate when you used a PowerLink? >> That event has been retold here a few times. >> After installing a new chain on used sprockets, the chain skipped >> occasionally on the 13t sprocket. One of these skips occurred at >> the precise moment before the PowerLink went into engagement and >> the inertia of following links compressed the chain enough to >> separate the link (after I had ridden more than 10 miles). > I haven't heard this before, and can't imagine the PowerLink > disengaging under tension even when rolling over such a small > diameter as a 13t sprocket. Cyclist have used the PowerLink > connector on 12t or even 11t sprockets without failure. The only way > I could possibly see the PowerLink disengaging, would be > backpedaling and having the chain getting hung-up to compress the > PowerLink enough to become disengaged. Slow down. Re read the description of PowerLink separation. It did not separate while that part of the chain was in tension! Jobst Brandt                       Date: 26 Jun 2007 13:30:32 From: Subject: Re: Safe to lengthen a chain? On 26 Jun 2007 19:17:45 GMT, jobst.brandt@stanfordalumni.org wrote: >Tom Nakashima writes: > >>>>> I haven't had a chain separate in use except the time I used a >>>>> PowerLink. > >>>> I'm curious, how did your chain separate when you used a >PowerLink? > >>> That event has been retold here a few times. > >>> After installing a new chain on used sprockets, the chain skipped >>> occasionally on the 13t sprocket. One of these skips occurred at >>> the precise moment before the PowerLink went into engagement and >>> the inertia of following links compressed the chain enough to >>> separate the link (after I had ridden more than 10 miles). > >> I haven't heard this before, and can't imagine the PowerLink >> disengaging under tension even when rolling over such a small >> diameter as a 13t sprocket. Cyclist have used the PowerLink >> connector on 12t or even 11t sprockets without failure. The only way >> I could possibly see the PowerLink disengaging, would be >> backpedaling and having the chain getting hung-up to compress the >> PowerLink enough to become disengaged. > >Slow down. Re read the description of PowerLink separation. It did >not separate while that part of the chain was in tension! > >Jobst Brandt Dear Jobst, Given gravity, when is any part of a bicycle chain not in at least some tension? Cheers, Carl Fogel                         Date: 26 Jun 2007 19:40:46 From: Subject: Re: Safe to lengthen a chain? Carl Fogel writes: >>>>>> I haven't had a chain separate in use except the time I used a >>>>>> PowerLink. >>>>> I'm curious, how did your chain separate when you used a >>>>> PowerLink? >>>> That event has been retold here a few times. >>>> After installing a new chain on used sprockets, the chain skipped >>>> occasionally on the 13t sprocket. One of these skips occurred at >>>> the precise moment before the PowerLink went into engagement and >>>> the inertia of following links compressed the chain enough to >>>> separate the link (after I had ridden more than 10 miles). >>> I haven't heard this before, and can't imagine the PowerLink >>> disengaging under tension even when rolling over such a small >>> diameter as a 13t sprocket. Cyclist have used the PowerLink >>> connector on 12t or even 11t sprockets without failure. The only >>> way I could possibly see the PowerLink disengaging, would be >>> backpedaling and having the chain getting hung-up to compress the >>> PowerLink enough to become disengaged. >> Slow down. Re-read the description of PowerLink separation. It >> did not separate while that part of the chain was in tension! > Given gravity, when is any part of a bicycle chain not in at least > some tension? INERTIA! Read the item! As the chain was going into engagement precisely at the moment the PowerLink approached the 13t sprocket, the chain skipped. Chain skip accelerates the chain to move forward in a few milliseconds and stops as the chain falls back into engagement. Inertia of the following chain compressed the PowerLink enough to make it fall apart. As I said, I walked back and found the undamaged parts and reconnected the chain using them to ride the rest of the way to work. I'm sure you can Google where I explained this event a couple of times in the past. Jobst Brandt                           Date: 26 Jun 2007 13:45:06 From: Subject: Re: Safe to lengthen a chain? On 26 Jun 2007 19:40:46 GMT, jobst.brandt@stanfordalumni.org wrote: >Carl Fogel writes: > >>>>>>> I haven't had a chain separate in use except the time I used a >>>>>>> PowerLink. > >>>>>> I'm curious, how did your chain separate when you used a >>>>>> PowerLink? > >>>>> That event has been retold here a few times. > >>>>> After installing a new chain on used sprockets, the chain skipped >>>>> occasionally on the 13t sprocket. One of these skips occurred at >>>>> the precise moment before the PowerLink went into engagement and >>>>> the inertia of following links compressed the chain enough to >>>>> separate the link (after I had ridden more than 10 miles). > >>>> I haven't heard this before, and can't imagine the PowerLink >>>> disengaging under tension even when rolling over such a small >>>> diameter as a 13t sprocket. Cyclist have used the PowerLink >>>> connector on 12t or even 11t sprockets without failure. The only >>>> way I could possibly see the PowerLink disengaging, would be >>>> backpedaling and having the chain getting hung-up to compress the >>>> PowerLink enough to become disengaged. > >>> Slow down. Re-read the description of PowerLink separation. It >>> did not separate while that part of the chain was in tension! > >> Given gravity, when is any part of a bicycle chain not in at least >> some tension? > >INERTIA! Read the item! As the chain was going into engagement >precisely at the moment the PowerLink approached the 13t sprocket, the >chain skipped. Chain skip accelerates the chain to move forward in a >few milliseconds and stops as the chain falls back into engagement. >Inertia of the following chain compressed the PowerLink enough to make >it fall apart. [snip] Dear Jobst, I'm still puzzled. Are you saying that a metal chain constantly slows down as it is _pulled_ onto a gear? Cheers, Carl Fogel                             Date: 26 Jun 2007 21:44:53 From: A Muzi Subject: Re: Safe to lengthen a chain? > jobst.brandt@stanfordalumni.org wrote: >>>>>>>> I haven't had a chain separate in use except the time I used a >>>>>>>> PowerLink. ?? >>>>>>> I'm curious, how did your chain separate when you used a >>>>>>> PowerLink? > jobst.brandt@stanfordalumni.org wrote: >>>>>> That event has been retold here a few times. >>>>>> After installing a new chain on used sprockets, the chain skipped >>>>>> occasionally on the 13t sprocket. One of these skips occurred at >>>>>> the precise moment before the PowerLink went into engagement and >>>>>> the inertia of following links compressed the chain enough to >>>>>> separate the link (after I had ridden more than 10 miles). ?? >>>>> I haven't heard this before, and can't imagine the PowerLink >>>>> disengaging under tension even when rolling over such a small >>>>> diameter as a 13t sprocket. Cyclist have used the PowerLink >>>>> connector on 12t or even 11t sprockets without failure. The only >>>>> way I could possibly see the PowerLink disengaging, would be >>>>> backpedaling and having the chain getting hung-up to compress the >>>>> PowerLink enough to become disengaged. > jobst.brandt@stanfordalumni.org wrote: >>>> Slow down. Re-read the description of PowerLink separation. It >>>> did not separate while that part of the chain was in tension! carlfogel@comcast.net wrote: >>> Given gravity, when is any part of a bicycle chain not in at least >>> some tension? > jobst.brandt@stanfordalumni.org wrote: >> INERTIA! Read the item! As the chain was going into engagement >> precisely at the moment the PowerLink approached the 13t sprocket, the >> chain skipped. Chain skip accelerates the chain to move forward in a >> few milliseconds and stops as the chain falls back into engagement. >> Inertia of the following chain compressed the PowerLink enough to make >> it fall apart. carlfogel@comcast.net wrote: > I'm still puzzled. > Are you saying that a metal chain constantly slows down as it is > _pulled_ onto a gear? I didn't think it was a cryptic or obtuse report at all. On a worn cog, a link rides up over the worn 13t cog. The following half of the link catches the tooth as the leading part falls back toward it, snapping open. One might assume a worn out-of-pitch cog with a new chain to visualize this. Watch a new chain as it tries to engage a worn cog. The phenomenon is distinctive, and noted by periodic rising/falling over then into the tooth. -- Andrew Muzi www.yellowjersey.org Open every day since 1 April, 1971                               Date: 26 Jun 2007 21:11:42 From: Subject: Re: Safe to lengthen a chain? On Tue, 26 Jun 2007 21:44:53 -0500, A Muzi <am@yellowjersey.org > wrote: >> jobst.brandt@stanfordalumni.org wrote: >>>>>>>>> I haven't had a chain separate in use except the time I used a >>>>>>>>> PowerLink. > >?? >>>>>>>> I'm curious, how did your chain separate when you used a >>>>>>>> PowerLink? > >> jobst.brandt@stanfordalumni.org wrote: >>>>>>> That event has been retold here a few times. >>>>>>> After installing a new chain on used sprockets, the chain skipped >>>>>>> occasionally on the 13t sprocket. One of these skips occurred at >>>>>>> the precise moment before the PowerLink went into engagement and >>>>>>> the inertia of following links compressed the chain enough to >>>>>>> separate the link (after I had ridden more than 10 miles). > >?? >>>>>> I haven't heard this before, and can't imagine the PowerLink >>>>>> disengaging under tension even when rolling over such a small >>>>>> diameter as a 13t sprocket. Cyclist have used the PowerLink >>>>>> connector on 12t or even 11t sprockets without failure. The only >>>>>> way I could possibly see the PowerLink disengaging, would be >>>>>> backpedaling and having the chain getting hung-up to compress the >>>>>> PowerLink enough to become disengaged. > >> jobst.brandt@stanfordalumni.org wrote: >>>>> Slow down. Re-read the description of PowerLink separation. It >>>>> did not separate while that part of the chain was in tension! > >carlfogel@comcast.net wrote: >>>> Given gravity, when is any part of a bicycle chain not in at least >>>> some tension? > >> jobst.brandt@stanfordalumni.org wrote: >>> INERTIA! Read the item! As the chain was going into engagement >>> precisely at the moment the PowerLink approached the 13t sprocket, the >>> chain skipped. Chain skip accelerates the chain to move forward in a >>> few milliseconds and stops as the chain falls back into engagement. >>> Inertia of the following chain compressed the PowerLink enough to make >>> it fall apart. > >carlfogel@comcast.net wrote: >> I'm still puzzled. >> Are you saying that a metal chain constantly slows down as it is >> _pulled_ onto a gear? > >I didn't think it was a cryptic or obtuse report at all. >On a worn cog, a link rides up over the worn 13t cog. The following half >of the link catches the tooth as the leading part falls back toward it, >snapping open. >One might assume a worn out-of-pitch cog with a new chain to visualize this. >Watch a new chain as it tries to engage a worn cog. The phenomenon is >distinctive, and noted by periodic rising/falling over then into the tooth. Dear Andrew, If quick-connect link is _on_ the first gear tooth, snapping down onto the tooth will force the two half-links apart, not together. If another link is snapping down on the first gear tooth and the quick-connect is just behind it (heading toward the gear), then it sounds like the first link is swinging and we're hoping that everything will line up to push the quick-connect apart. This sounds unlikely to me. Lay a chain on its side on a table with a quick link. Line things up however you please, and try to knock the quick link apart by tapping the link beyond it with a hammer. If the link beyond the quick-link is riding up and then snapping down, then the angle will be bad for hitting the quick-link. Unless the quick-link is struck dead-on, the two halves aren't likely to close and allow separation--and even then, they'd be a millsecond from being forced apart again by the gear tooth. Still, I suppose that the weight of the chain, the bounce of the chain, and other factors could theoretically knock an oncoming quick link just right. But I'd wonder first about defective quick links and quick links that weren't put together quite right, due to defects or grime or whatever. Every year, I skip at least one new chain with a quick-link on a 53x11 for 15 miles. Then I put a new 11-tooth on and resolve to replace the chain sooner. Exactly how much chain is wrapping around the small gear, how hard the rider pedals, road bounce, and other things may be protecting me. As a bike shop owner, have you had any customers who complained that their quick links flew apart when their chains began skipping? Cheers, Carl Fogel                                 Date: 26 Jun 2007 23:55:30 From: A Muzi Subject: Re: Safe to lengthen a chain? -snip- >>> jobst.brandt@stanfordalumni.org wrote: >>>>>>>> After installing a new chain on used sprockets, the chain skipped >>>>>>>> occasionally on the 13t sprocket. One of these skips occurred at >>>>>>>> the precise moment before the PowerLink went into engagement and >>>>>>>> the inertia of following links compressed the chain enough to >>>>>>>> separate the link (after I had ridden more than 10 miles). >> ?? >>>>>>> I haven't heard this before, and can't imagine the PowerLink -snip- >> carlfogel@comcast.net wrote: >>> I'm still puzzled. >>> Are you saying that a metal chain constantly slows down as it is >>> _pulled_ onto a gear? > A Muzi <am@yellowjersey.org> wrote: >> On a worn cog, a link rides up over the worn 13t cog. The following half >> of the link catches the tooth as the leading part falls back toward it, >> snapping open. >> One might assume a worn out-of-pitch cog with a new chain to visualize this. >> Watch a new chain as it tries to engage a worn cog. The phenomenon is >> distinctive, and noted by periodic rising/falling over then into the tooth. carlfogel@comcast.net wrote: > If quick-connect link is _on_ the first gear tooth, snapping down onto > the tooth will force the two half-links apart, not together. > > If another link is snapping down on the first gear tooth and the > quick-connect is just behind it (heading toward the gear), then it > sounds like the first link is swinging and we're hoping that > everything will line up to push the quick-connect apart. > > This sounds unlikely to me. > > Lay a chain on its side on a table with a quick link. Line things up > however you please, and try to knock the quick link apart by tapping > the link beyond it with a hammer. > > If the link beyond the quick-link is riding up and then snapping down, > then the angle will be bad for hitting the quick-link. Unless the > quick-link is struck dead-on, the two halves aren't likely to close > and allow separation--and even then, they'd be a millsecond from being > forced apart again by the gear tooth. > > Still, I suppose that the weight of the chain, the bounce of the > chain, and other factors could theoretically knock an oncoming quick > link just right. > > But I'd wonder first about defective quick links and quick links that > weren't put together quite right, due to defects or grime or whatever. > > Every year, I skip at least one new chain with a quick-link on a 53x11 > for 15 miles. Then I put a new 11-tooth on and resolve to replace the > chain sooner. Exactly how much chain is wrapping around the small > gear, how hard the rider pedals, road bounce, and other things may be > protecting me. > > As a bike shop owner, have you had any customers who complained that > their quick links flew apart when their chains began skipping? I think we can all agree this was an unusual event. No, I've never seen such, nor heard a similar report but it's perfectly plausible IMHO. -- Andrew Muzi www.yellowjersey.org Open every day since 1 April, 1971                                   Date: 27 Jun 2007 18:21:53 From: Subject: Re: Safe to lengthen a chain? On Tue, 26 Jun 2007 23:55:30 -0500, A Muzi <am@yellowjersey.org > wrote: >-snip- >>>> jobst.brandt@stanfordalumni.org wrote: >>>>>>>>> After installing a new chain on used sprockets, the chain skipped >>>>>>>>> occasionally on the 13t sprocket. One of these skips occurred at >>>>>>>>> the precise moment before the PowerLink went into engagement and >>>>>>>>> the inertia of following links compressed the chain enough to >>>>>>>>> separate the link (after I had ridden more than 10 miles). > >>> ?? >>>>>>>> I haven't heard this before, and can't imagine the PowerLink >-snip- > >>> carlfogel@comcast.net wrote: >>>> I'm still puzzled. >>>> Are you saying that a metal chain constantly slows down as it is >>>> _pulled_ onto a gear? > >> A Muzi <am@yellowjersey.org> wrote: >>> On a worn cog, a link rides up over the worn 13t cog. The following half >>> of the link catches the tooth as the leading part falls back toward it, >>> snapping open. >>> One might assume a worn out-of-pitch cog with a new chain to visualize this. >>> Watch a new chain as it tries to engage a worn cog. The phenomenon is >>> distinctive, and noted by periodic rising/falling over then into the tooth. > >carlfogel@comcast.net wrote: >> If quick-connect link is _on_ the first gear tooth, snapping down onto >> the tooth will force the two half-links apart, not together. >> >> If another link is snapping down on the first gear tooth and the >> quick-connect is just behind it (heading toward the gear), then it >> sounds like the first link is swinging and we're hoping that >> everything will line up to push the quick-connect apart. >> >> This sounds unlikely to me. >> >> Lay a chain on its side on a table with a quick link. Line things up >> however you please, and try to knock the quick link apart by tapping >> the link beyond it with a hammer. >> >> If the link beyond the quick-link is riding up and then snapping down, >> then the angle will be bad for hitting the quick-link. Unless the >> quick-link is struck dead-on, the two halves aren't likely to close >> and allow separation--and even then, they'd be a millsecond from being >> forced apart again by the gear tooth. >> >> Still, I suppose that the weight of the chain, the bounce of the >> chain, and other factors could theoretically knock an oncoming quick >> link just right. >> >> But I'd wonder first about defective quick links and quick links that >> weren't put together quite right, due to defects or grime or whatever. >> >> Every year, I skip at least one new chain with a quick-link on a 53x11 >> for 15 miles. Then I put a new 11-tooth on and resolve to replace the >> chain sooner. Exactly how much chain is wrapping around the small >> gear, how hard the rider pedals, road bounce, and other things may be >> protecting me. >> >> As a bike shop owner, have you had any customers who complained that >> their quick links flew apart when their chains began skipping? > >I think we can all agree this was an unusual event. No, I've never seen >such, nor heard a similar report but it's perfectly plausible IMHO. Dear Andrew, I think that we agree. It's rare for a quick-connect to come apart after a few miles of use. But a skipping tooth might bang things just right. I'm just skeptical, since there are at least two other possibilities, namely a defective link and a good link that wasn't seated quite right. Several other posters did come forward right away and mentioned problems with quick-connects. Some of them involved broken and bent links, but that could be just worse luck after the quick-connect's initial separation. I'm not sure if anyone else recalled a chain skipping just before its quick-connect came apart. I have some old chains and quick-connect links and plan to see if I can knock them apart by rapping the next link. It may turn out to be like the mechanical lock pick, which can often open otherwise tricky pin tumbler locks with little more than a sharp rap. Or, to use a more familiar example, the Bic pen method of unlocking tubular key bicycle locks: http://groups.google.com/group/rec.bicycles.tech/browse_thread/thread/d9d488e1dec3b1f6/f7a429cdc83dca15?lnk=gst&q=lock+bic&rnum=1#f7a429cdc83dca15 But if a sharp rap does open a quick-connect, I'll have to wonder why they don't fly apart when riders are jolting down bumpy hills. A quick-connect just about to enter or leave the front sprocket has the whole chain run banging it forward to compress things, and it has a good chance of being in that position during a year's riding. Time to make a mess of the workbench with some old chains! Cheers, Carl Fogel                                     Date: 28 Jun 2007 01:12:04 From: Subject: Re: Safe to lengthen a chain? Carl Fogel writes: > But if a sharp rap does open a quick-connect, I'll have to wonder > why they don't fly apart when riders are jolting down bumpy hills. A > quick-connect just about to enter or leave the front sprocket has > the whole chain run banging it forward to compress things, and it > has a good chance of being in that position during a year's riding. That is the method for disconnecting such links, pushing them in axial compression. However, both side plates of the SuperLink must be in contact with the links it is connecting and that cannot occur when the link has dirty lube. You may recall that I had difficulty manually separating that same link after about 200 miles of varied use (after I reinstalled it on the road when it separated). I only used one such link before realizing it had no merit for my use. > Time to make a mess of the workbench with some old chains! Best make that "new chains" and clean links at that. Ones without grease or oil and grit at the link in question. Jobst Brandt                                       Date: 28 Jun 2007 03:54:59 From: Subject: Re: Safe to lengthen a chain? Carl Fogel writes: > But if a sharp rap does open a quick-connect, I'll have to wonder > why they don't fly apart when riders are jolting down bumpy hills. A > quick-connect just about to enter or leave the front sprocket has > the whole chain run banging it forward to compress things, and it > has a good chance of being in that position during a year's riding. Looking for a way to emulate the link separation I experienced, I believe a good method would be to attach one inner chain link to a rubber band hung from a roof like metal strut, and attach about three inches of chain to that link using a clean SuperLink. After pressing the SuperLink side plates together manually before pulling down on the loose end of chain, allowing it to spring upward to strike the ceiling a few times may release the cover plate and the rest is history. Jobst Brandt                                         Date: 28 Jun 2007 02:01:42 From: Subject: Re: Safe to lengthen a chain? On 28 Jun 2007 03:54:59 GMT, jobst.brandt@stanfordalumni.org wrote: >Carl Fogel writes: > >> But if a sharp rap does open a quick-connect, I'll have to wonder >> why they don't fly apart when riders are jolting down bumpy hills. A >> quick-connect just about to enter or leave the front sprocket has >> the whole chain run banging it forward to compress things, and it >> has a good chance of being in that position during a year's riding. > >Looking for a way to emulate the link separation I experienced, I >believe a good method would be to attach one inner chain link to a >rubber band hung from a roof like metal strut, and attach about three >inches of chain to that link using a clean SuperLink. After pressing >the SuperLink side plates together manually before pulling down on the >loose end of chain, allowing it to spring upward to strike the ceiling >a few times may release the cover plate and the rest is history. > >Jobst Brandt Dear Jobst, The more I think about it, the less sure I am about any tests suggested so far. What kind of backwards effect should we expect from a skipping chain link that first rides up on a worn 13-tooth and then snaps back toward the axle? Is the effect reasonably close to firing a couple of links against a metal pipe with a rubber band like a spitwad? Or banging one end of a chain laid on a table with a hammer? I don't know how to calculate the energy, momentum, impact, impulse, or whatever is involved in either case, but I'm hoping that someone like you or Joe Riel or Luns Tee does know how and will find the question interesting enough to come up with some kind of figures. Cheers, Carl Fogel                                           Date: 28 Jun 2007 18:12:16 From: Subject: Re: Safe to lengthen a chain? Carl Fogel writes: >>> But if a sharp rap does open a quick-connect, I'll have to wonder >>> why they don't fly apart when riders are jolting down bumpy >>> hills. A quick-connect just about to enter or leave the front >>> sprocket has the whole chain run banging it forward to compress >>> things, and it has a good chance of being in that position during >>> a year's riding. >> Looking for a way to emulate the link separation I experienced, I >> believe a good method would be to attach one inner chain link to a >> rubber band hung from a roof like metal strut, and attach about >> three inches of chain to that link using a clean SuperLink. After >> pressing the SuperLink side plates together manually before pulling >> down on the loose end of chain, allowing it to spring upward to >> strike the ceiling a few times may release the cover plate and the >> rest is history. > The more I think about it, the less sure I am about any tests > suggested so far. > What kind of backward effect should we expect from a skipping chain > link that first rides up on a worn 13-tooth and then snaps back > toward the axle? Just think of it as a chain that jumps forward rapidly and more suddenly stops as the chain is pulled forcefully into engagement with the sprocket. It produces a sudden forward acceleration followed by an even faster negative acceleration, the one that causes slack in the links to be taken up. The action is fast enough to leave the derailleur tensioning in the dust. That is, the chain is not bearing on the idler wheels, the treadle not being able to move that fast. > Is the effect reasonably close to firing a couple of links against a > metal pipe with a rubber band like a spitwad? Or banging one end of > a chain laid on a table with a hammer? On-the-table has the bias of guaranteeing a straight line even when compressed. As you may have noticed, a chain can be pushed across a table (pins horizontal) but not (pins vertical). > I don't know how to calculate the energy, momentum, impact, impulse, > or whatever is involved in either case, but I'm hoping that someone > like you or Joe Riel or Luns Tee does know how and will find the > question interesting enough to come up with some kind of figures. You don't need no steenkin calculations, you are searching for physical evidence. Jobst Brandt                                             Date: 28 Jun 2007 13:32:02 From: Subject: Re: Safe to lengthen a chain? On 28 Jun 2007 18:12:16 GMT, jobst.brandt@stanfordalumni.org wrote: >Carl Fogel writes: > >>>> But if a sharp rap does open a quick-connect, I'll have to wonder >>>> why they don't fly apart when riders are jolting down bumpy >>>> hills. A quick-connect just about to enter or leave the front >>>> sprocket has the whole chain run banging it forward to compress >>>> things, and it has a good chance of being in that position during >>>> a year's riding. > >>> Looking for a way to emulate the link separation I experienced, I >>> believe a good method would be to attach one inner chain link to a >>> rubber band hung from a roof like metal strut, and attach about >>> three inches of chain to that link using a clean SuperLink. After >>> pressing the SuperLink side plates together manually before pulling >>> down on the loose end of chain, allowing it to spring upward to >>> strike the ceiling a few times may release the cover plate and the >>> rest is history. > >> The more I think about it, the less sure I am about any tests >> suggested so far. > >> What kind of backward effect should we expect from a skipping chain >> link that first rides up on a worn 13-tooth and then snaps back >> toward the axle? > >Just think of it as a chain that jumps forward rapidly and more >suddenly stops as the chain is pulled forcefully into engagement with >the sprocket. It produces a sudden forward acceleration followed by >an even faster negative acceleration, the one that causes slack in the >links to be taken up. The action is fast enough to leave the >derailleur tensioning in the dust. That is, the chain is not bearing >on the idler wheels, the treadle not being able to move that fast. > >> Is the effect reasonably close to firing a couple of links against a >> metal pipe with a rubber band like a spitwad? Or banging one end of >> a chain laid on a table with a hammer? > >On-the-table has the bias of guaranteeing a straight line even when >compressed. As you may have noticed, a chain can be pushed across a >table (pins horizontal) but not (pins vertical). > >> I don't know how to calculate the energy, momentum, impact, impulse, >> or whatever is involved in either case, but I'm hoping that someone >> like you or Joe Riel or Luns Tee does know how and will find the >> question interesting enough to come up with some kind of figures. > >You don't need no steenkin calculations, you are searching for >physical evidence. > >Jobst Brandt Dear Jobst, Er, yes, I do need some steenkin calculations or a better example. The chain must do all its acceleration within half an inch as it skips to the next position on the 13-tooth. The mass of the whole chain, the entire crank, and both legs of the rider must be accelerated by the force or tension or whatever it is being applied on the leading pedal. A quick test with a fairly normal rubber band showed that it will accelerate a much lighter three-inch chain section, spitball-style, up to fifty feet down my driveway. I'm looking into some calculators and details, but I suspect that I'll end up suggesting this comparison: Attach a chain link to the trailing pedal arm on a level crank, placing the link out as far as the chain ring. Now attach a quick-connect to the link hanging from the pedal arm and dangle a couple more chain links from that. I _think_ that this resembles your rubber band suggestion, but it duplicates the actual acceleration that would occur back where the short section of chain skips and slams into the new position on the gear teeth. The crank should accelerate and decelerate with the same half-inch jerk. If so, I'm skeptical about that impact being enough to knock anything loose. The jerk of a skipping chain _feels_ impressive because the rider's leg is involved, but I don't think that the whole mass of the leg-crank-chain accelerates to anything like rubber-band velocity in half an inch. In other words, I do think that your rubber band idea is elegant, but I suspect that it may exaggerate the actual velocity enormously. I don't get the feeling when my 11-tooth skips that my leg might fly 50 feet down the road. But that's all _feeling_, not calculation. Here's a crude drawing of what I'm trying to describe: http://i9.tinypic.com/4v38hhl.jpg I left out the legs, since I can't draw worth a damn, but the leading leg provides the force, while the mass of both legs has to accelerate, along with the crank and chain. My question is whether the real chain acceleration is far less than my crude whack-with-a-hammer or your elegant rubber-band and a few inches of chain acceleration, which I suspect involve much higher speeds and greater distances, despite much smaller forces. Cheers, Carl Fogel                                               Date: 28 Jun 2007 21:47:05 From: Subject: Re: Safe to lengthen a chain? Carl Fogel writes: >>>>> But if a sharp rap does open a quick-connect, I'll have to >>>>> wonder why they don't fly apart when riders are jolting down >>>>> bumpy hills. A quick-connect just about to enter or leave the >>>>> front sprocket has the whole chain run banging it forward to >>>>> compress things, and it has a good chance of being in that >>>>> position during a year's riding. >>>> Looking for a way to emulate the link separation I experienced, I >>>> believe a good method would be to attach one inner chain link to >>>> a rubber band hung from a roof like metal strut, and attach about >>>> three inches of chain to that link using a clean SuperLink. >>>> After pressing the SuperLink side plates together manually before >>>> pulling down on the loose end of chain, allowing it to spring >>>> upward to strike the ceiling a few times may release the cover >>>> plate and the rest is history. >>> The more I think about it, the less sure I am about any tests >>> suggested so far. >>> What kind of backward effect should we expect from a skipping >>> chain link that first rides up on a worn 13-tooth and then snaps >>> back toward the axle? >> Just think of it as a chain that jumps forward rapidly and more >> suddenly stops as the chain is pulled forcefully into engagement >> with the sprocket. It produces a sudden forward acceleration >> followed by an even faster negative acceleration, the one that >> causes slack in the links to be taken up. The action is fast >> enough to leave the derailleur tensioning in the dust. That is, >> the chain is not bearing on the idler wheels, the treadle not being >> able to move that fast. >>> Is the effect reasonably close to firing a couple of links against >>> a metal pipe with a rubber band like a spitwad? Or banging one >>> end of a chain laid on a table with a hammer? >> On-the-table has the bias of guaranteeing a straight line even when >> compressed. As you may have noticed, a chain can be pushed across >> a table (pins horizontal) but not (pins vertical). >>> I don't know how to calculate the energy, momentum, impact, >>> impulse, or whatever is involved in either case, but I'm hoping >>> that someone like you or Joe Riel or Luns Tee does know how and >>> will find the question interesting enough to come up with some >>> kind of figures. >> You don't need no steenkin calculations, you are searching for >> physical evidence. > Er, yes, I do need some steenkin calculations or a better example. > The chain must do all its acceleration within half an inch as it > skips to the next position on the 13-tooth. > The mass of the whole chain, the entire crank, and both legs of the > rider must be accelerated by the force or tension or whatever it is > being applied on the leading pedal. All that takes place in the duration of a snap of ones finger. It is a sharp clack, the whole event taking a few milliseconds. It is certainly faster than a derailleur can articulate with the mass of a chain pressing against its idlers. Skips like this do not occur unless there is substantial tension on the chain bearing on the sprocket, so when it fails to engage, it snaps over to the next engagement with a sharp clack. > A quick test with a fairly normal rubber band showed that it will > accelerate a much lighter three-inch chain section, spitball-style, > up to fifty feet down my driveway. Well, I don't know at what trajectory you tried that. 45=C2=B0 is close = to maximum range, but that tells us little. I don't know how far a piece of chain would fly at the rate of chain skip over a hooked sprocket. I doubt anyone has the equipment available to do some high speed photography of chain skip. > I'm looking into some calculators and details, but I suspect that > I'll end up suggesting this comparison: > Attach a chain link to the trailing pedal arm on a level crank, > placing the link out as far as the chain ring. > Now attach a quick-connect to the link hanging from the pedal arm > and dangle a couple more chain links from that. > I _think_ that this resembles your rubber band suggestion, but it > duplicates the actual acceleration that would occur back where the > short section of chain skips and slams into the new position on the > gear teeth. The crank should accelerate and decelerate with the same > half-inch jerk. I don't see how there is any parallel. I can't accelerate my pedals from a standstill anywhere near as fast as a chain skip that starts with an enormous preload. If you were to have an explosive pin in a chain, tension the chain as on a bicycle with a rider pushing hard and then pop the pin, you could get a similar acceleration. I don't think your example approaches those conditions. > If so, I'm skeptical about that impact being enough to knock > anything loose. The jerk of a skipping chain _feels_ impressive > because the rider's leg is involved, but I don't think that the > whole mass of the leg-crank-chain accelerates to anything like > rubber-band velocity in half an inch. I find it impressive because it occurs so quickly and is over so quickly. I don't notice much foot movement except for a sharp shudder, much of which is the result of lateral frame flex from momentary no-load. > In other words, I do think that your rubber band idea is elegant, > but I suspect that it may exaggerate the actual velocity enormously. > I don't get the feeling when my 11-tooth skips that my leg might fly > 50 feet down the road. I doubt it. The acceleration of the chain is possible only because there is stored energy in the frame. We discuss frame flex here endlessly and where all the lost power goes. > But that's all _feeling_, not calculation. To calculate, you need an accurate model and we don't know all the variables so the calculation would be no better than not calculating. > Here's a crude drawing of what I'm trying to describe: http://i9.tinypic.com/4v38hhl.jpg > I left out the legs, since I can't draw worth a damn, but the > leading leg provides the force, while the mass of both legs has to > accelerate, along with the crank and chain. Your model does not represent the bicycle as I said above. The foot does not need to accelerate for this to occur and the leg not at all, the articulation of the ankle coming first. Even that is not what moves with a chain skip. Try it and look at how the BB moves laterally. > My question is whether the real chain acceleration is far less than > my crude whack-with-a-hammer or your elegant rubber-band and a few > inches of chain acceleration, which I suspect involve much higher > speeds and greater distances, despite much smaller forces. I wouldn't worry about that as long as the force is great enough to slide the link open. If that is possible the magnitude of that can be argued, but I am doubtful that without many repetitions, any disengagements can be achieved. I say that because plenty of chain skips occur and no one has reported such a disengagement. Jobst Brandt                                                 Date: 28 Jun 2007 21:22:27 From: Subject: Re: Safe to lengthen a chain? On 28 Jun 2007 21:47:05 GMT, jobst.brandt@stanfordalumni.org wrote: >Carl Fogel writes: > >>>>>> But if a sharp rap does open a quick-connect, I'll have to >>>>>> wonder why they don't fly apart when riders are jolting down >>>>>> bumpy hills. A quick-connect just about to enter or leave the >>>>>> front sprocket has the whole chain run banging it forward to >>>>>> compress things, and it has a good chance of being in that >>>>>> position during a year's riding. > >>>>> Looking for a way to emulate the link separation I experienced, I >>>>> believe a good method would be to attach one inner chain link to >>>>> a rubber band hung from a roof like metal strut, and attach about >>>>> three inches of chain to that link using a clean SuperLink. >>>>> After pressing the SuperLink side plates together manually before >>>>> pulling down on the loose end of chain, allowing it to spring >>>>> upward to strike the ceiling a few times may release the cover >>>>> plate and the rest is history. > >>>> The more I think about it, the less sure I am about any tests >>>> suggested so far. > >>>> What kind of backward effect should we expect from a skipping >>>> chain link that first rides up on a worn 13-tooth and then snaps >>>> back toward the axle? > >>> Just think of it as a chain that jumps forward rapidly and more >>> suddenly stops as the chain is pulled forcefully into engagement >>> with the sprocket. It produces a sudden forward acceleration >>> followed by an even faster negative acceleration, the one that >>> causes slack in the links to be taken up. The action is fast >>> enough to leave the derailleur tensioning in the dust. That is, >>> the chain is not bearing on the idler wheels, the treadle not being >>> able to move that fast. > >>>> Is the effect reasonably close to firing a couple of links against >>>> a metal pipe with a rubber band like a spitwad? Or banging one >>>> end of a chain laid on a table with a hammer? > >>> On-the-table has the bias of guaranteeing a straight line even when >>> compressed. As you may have noticed, a chain can be pushed across >>> a table (pins horizontal) but not (pins vertical). > >>>> I don't know how to calculate the energy, momentum, impact, >>>> impulse, or whatever is involved in either case, but I'm hoping >>>> that someone like you or Joe Riel or Luns Tee does know how and >>>> will find the question interesting enough to come up with some >>>> kind of figures. > >>> You don't need no steenkin calculations, you are searching for >>> physical evidence. > >> Er, yes, I do need some steenkin calculations or a better example. > >> The chain must do all its acceleration within half an inch as it >> skips to the next position on the 13-tooth. > >> The mass of the whole chain, the entire crank, and both legs of the >> rider must be accelerated by the force or tension or whatever it is >> being applied on the leading pedal. > >All that takes place in the duration of a snap of ones finger. It is >a sharp clack, the whole event taking a few milliseconds. It is >certainly faster than a derailleur can articulate with the mass of a >chain pressing against its idlers. Skips like this do not occur >unless there is substantial tension on the chain bearing on the >sprocket, so when it fails to engage, it snaps over to the next >engagement with a sharp clack. > >> A quick test with a fairly normal rubber band showed that it will >> accelerate a much lighter three-inch chain section, spitball-style, >> up to fifty feet down my driveway. > >Well, I don't know at what trajectory you tried that. 45° is close to >maximum range, but that tells us little. I don't know how far a piece >of chain would fly at the rate of chain skip over a hooked sprocket. >I doubt anyone has the equipment available to do some high speed >photography of chain skip. > >> I'm looking into some calculators and details, but I suspect that >> I'll end up suggesting this comparison: > >> Attach a chain link to the trailing pedal arm on a level crank, >> placing the link out as far as the chain ring. > >> Now attach a quick-connect to the link hanging from the pedal arm >> and dangle a couple more chain links from that. > >> I _think_ that this resembles your rubber band suggestion, but it >> duplicates the actual acceleration that would occur back where the >> short section of chain skips and slams into the new position on the >> gear teeth. The crank should accelerate and decelerate with the same >> half-inch jerk. > >I don't see how there is any parallel. I can't accelerate my pedals >from a standstill anywhere near as fast as a chain skip that starts >with an enormous preload. If you were to have an explosive pin in a >chain, tension the chain as on a bicycle with a rider pushing hard and >then pop the pin, you could get a similar acceleration. I don't think >your example approaches those conditions. > >> If so, I'm skeptical about that impact being enough to knock >> anything loose. The jerk of a skipping chain _feels_ impressive >> because the rider's leg is involved, but I don't think that the >> whole mass of the leg-crank-chain accelerates to anything like >> rubber-band velocity in half an inch. > >I find it impressive because it occurs so quickly and is over so >quickly. I don't notice much foot movement except for a sharp >shudder, much of which is the result of lateral frame flex from >momentary no-load. > >> In other words, I do think that your rubber band idea is elegant, >> but I suspect that it may exaggerate the actual velocity enormously. >> I don't get the feeling when my 11-tooth skips that my leg might fly >> 50 feet down the road. > >I doubt it. The acceleration of the chain is possible only because >there is stored energy in the frame. We discuss frame flex here >endlessly and where all the lost power goes. > >> But that's all _feeling_, not calculation. > >To calculate, you need an accurate model and we don't know all the >variables so the calculation would be no better than not calculating. > >> Here's a crude drawing of what I'm trying to describe: > > http://i9.tinypic.com/4v38hhl.jpg > >> I left out the legs, since I can't draw worth a damn, but the >> leading leg provides the force, while the mass of both legs has to >> accelerate, along with the crank and chain. > >Your model does not represent the bicycle as I said above. The foot >does not need to accelerate for this to occur and the leg not at all, >the articulation of the ankle coming first. Even that is not what >moves with a chain skip. Try it and look at how the BB moves >laterally. > >> My question is whether the real chain acceleration is far less than >> my crude whack-with-a-hammer or your elegant rubber-band and a few >> inches of chain acceleration, which I suspect involve much higher >> speeds and greater distances, despite much smaller forces. > >I wouldn't worry about that as long as the force is great enough to >slide the link open. If that is possible the magnitude of that can be >argued, but I am doubtful that without many repetitions, any >disengagements can be achieved. I say that because plenty of chain >skips occur and no one has reported such a disengagement. > >Jobst Brandt Dear Jobst, I think that the tiny distance involved makes it next to impossible for a human being to guess the speeds involved. Here's a free-fall calculator: http://hyperphysics.phy-astr.gsu.edu/hbase/traj.html If the chain accelerates at free-fall velocity (it may go much faster), then it will cover the whole half an inch involved in a skip (0.04167 feet) in 0.051 seconds, about a twentieth of a second. But the chain would be traveling at only the pathetically slow speed of 1.637 feet per second, about 1.1 mph. The chain can easily go faster if a force greater than gravity is applied to a mass, but that involves accelerating two legs, the crank, and the whole chain to the kind of speed achieved with a rubber band and a short section of chain. I think that elastic storage is the best hope My quick test with a rubber band showed that it will fling a few inches of chain spitwad-style about fifty feet down the driveway in about a second--that's close to two orders of magnitude more acceleration, but it's from a miniature bow-and-arrow with considerably more than half an inch of draw. I agree that _if_ there's a lot of usable force stored elastically in the upper run and frame, then the short section of the chain may accelerate to a high speed relative to the gear tooth half an inch away. But I don't know how to measure this speed practically or predict it theoretically. So all that I can say is that the actual speed in a chain skip may be less than, equal to, or greater than the surprisingly large acceleration that a rubber band imparts to a short section of free chain. (Obviously, lengthening the short chain to run it around the two idler pulleys would add the mass of the pulleys, their arms, and the additional length of the chain, which the skip has to yank and accelerate in the real world.) I have no idea how well 40+ multi-piece chain links will store and release energy at the level of a rider pushing on one pedal. That's why I'm still curious about calculations. It seems to be a much trickier situation than I imagined when I was thinking of my original whack-it-with-hammer test or when I was admiring your more elegant rubber-band test. Cheers, Carl Fogel                                                   Date: 29 Jun 2007 04:36:48 From: Subject: Re: Safe to lengthen a chain? Carl Fogel writes: >>>>>>> But if a sharp rap does open a quick-connect, I'll have to >>>>>>> wonder why they don't fly apart when riders are jolting down >>>>>>> bumpy hills. A quick-connect just about to enter or leave the >>>>>>> front sprocket has the whole chain run banging it forward to >>>>>>> compress things, and it has a good chance of being in that >>>>>>> position during a year's riding. >>>>>> Looking for a way to emulate the link separation I experienced, >>>>>> I believe a good method would be to attach one inner chain link >>>>>> to a rubber band hung from a roof like metal strut, and attach >>>>>> about three inches of chain to that link using a clean >>>>>> SuperLink. After pressing the SuperLink side plates together >>>>>> manually before pulling down on the loose end of chain, >>>>>> allowing it to spring upward to strike the ceiling a few times >>>>>> may release the cover plate and the rest is history. >>>>> The more I think about it, the less sure I am about any tests >>>>> suggested so far. >>>>> What kind of backward effect should we expect from a skipping >>>>> chain link that first rides up on a worn 13-tooth and then snaps >>>>> back toward the axle? >>>> Just think of it as a chain that jumps forward rapidly and more >>>> suddenly stops as the chain is pulled forcefully into engagement >>>> with the sprocket. It produces a sudden forward acceleration >>>> followed by an even faster negative acceleration, the one that >>>> causes slack in the links to be taken up. The action is fast >>>> enough to leave the derailleur tensioning in the dust. That is, >>>> the chain is not bearing on the idler wheels, the treadle not >>>> being able to move that fast. >>>>> Is the effect reasonably close to firing a couple of links >>>>> against a metal pipe with a rubber band like a spitwad? Or >>>>> banging one end of a chain laid on a table with a hammer? >>>> On-the-table has the bias of guaranteeing a straight line even >>>> when compressed. As you may have noticed, a chain can be pushed >>>> across a table (pins horizontal) but not (pins vertical). >>>>> I don't know how to calculate the energy, momentum, impact, >>>>> impulse, or whatever is involved in either case, but I'm hoping >>>>> that someone like you or Joe Riel or Luns Tee does know how and >>>>> will find the question interesting enough to come up with some >>>>> kind of figures. >>>> You don't need no steenkin calculations, you are searching for >>>> physical evidence. >>> Er, yes, I do need some steenkin calculations or a better example. >>> The chain must do all its acceleration within half an inch as it >>> skips to the next position on the 13-tooth. >>> The mass of the whole chain, the entire crank, and both legs of >>> the rider must be accelerated by the force or tension or whatever >>> it is being applied on the leading pedal. >> All that takes place in the duration of a snap of ones finger. It >> is a sharp clack, the whole event taking a few milliseconds. It is >> certainly faster than a derailleur can articulate with the mass of >> a chain pressing against its idlers. Skips like this do not occur >> unless there is substantial tension on the chain bearing on the >> sprocket, so when it fails to engage, it snaps over to the next >> engagement with a sharp clack. > A quick test with a fairly normal >> rubber band showed that it will > accelerate a much lighter >> three-inch chain section, spitball-style, > up to fifty feet down >> my driveway. Well, I don't know at what trajectory you tried that. >> 45=C2=B0 is close to maximum range, but that tells us little. I don't >> know how far a piece of chain would fly at the rate of chain skip >> over a hooked sprocket. I doubt anyone has the equipment available >> to do some high speed photography of chain skip. > I'm looking >> into some calculators and details, but I suspect that > I'll end up >> suggesting this comparison: > Attach a chain link to the trailing >> pedal arm on a level crank, > placing the link out as far as the >> chain ring. > Now attach a quick-connect to the link hanging from >> the pedal arm > and dangle a couple more chain links from that. > >> I _think_ that this resembles your rubber band suggestion, but it > >> duplicates the actual acceleration that would occur back where the >> > short section of chain skips and slams into the new position on >> the > gear teeth. The crank should accelerate and decelerate with >> the same > half-inch jerk. I don't see how there is any parallel. >> I can't accelerate my pedals from a standstill anywhere near as >> fast as a chain skip that starts with an enormous preload. If you >> were to have an explosive pin in a chain, tension the chain as on a >> bicycle with a rider pushing hard and then pop the pin, you could >> get a similar acceleration. I don't think your example approaches >> those conditions. > If so, I'm skeptical about that impact being >> enough to knock > anything loose. The jerk of a skipping chain >> _feels_ impressive > because the rider's leg is involved, but I >> don't think that the > whole mass of the leg-crank-chain >> accelerates to anything like > rubber-band velocity in half an >> inch. I find it impressive because it occurs so quickly and is >> over so quickly. I don't notice much foot movement except for a >> sharp shudder, much of which is the result of lateral frame flex >> from momentary no-load. > In other words, I do think that your >> rubber band idea is elegant, > but I suspect that it may exaggerate >> the actual velocity enormously. > I don't get the feeling when my >> 11-tooth skips that my leg might fly > 50 feet down the road. I >> doubt it. The acceleration of the chain is possible only because >> there is stored energy in the frame. We discuss frame flex here >> endlessly and where all the lost power goes. > But that's all >> _feeling_, not calculation. To calculate, you need an accurate >> model and we don't know all the variables so the calculation would >> be no better than not calculating. > Here's a crude drawing of >> what I'm trying to describe: http://i9.tinypic.com/4v38hhl.jpg > I >> left out the legs, since I can't draw worth a damn, but the > >> leading leg provides the force, while the mass of both legs has to >> > accelerate, along with the crank and chain. Your model does not >> represent the bicycle as I said above. The foot does not need to >> accelerate for this to occur and the leg not at all, the >> articulation of the ankle coming first. Even that is not what >> moves with a chain skip. Try it and look at how the BB moves >> laterally. > My question is whether the real chain acceleration is >> far less than > my crude whack-with-a-hammer or your elegant >> rubber-band and a few > inches of chain acceleration, which I >> suspect involve much higher > speeds and greater distances, despite >> much smaller forces. I wouldn't worry about that as long as the >> force is great enough to slide the link open. If that is possible >> the magnitude of that can be argued, but I am doubtful that without >> many repetitions, any disengagements can be achieved. I say that >> because plenty of chain skips occur and no one has reported such a >> disengagement. > I think that the tiny distance involved makes it next to impossible > for a human being to guess the speeds involved. > Here's a free-fall calculator: http://hyperphysics.phy-astr.gsu.edu/hbase/traj.html Th only reason for retaining all that verbiage above is to ask you to read it. I am familiar with chain skip and am certain that it occurs in less than 10ms, or as I said, the sound of a snap of the fingers. The skip occurs faster than a foot can advance but with large muscular force already applied, there is no doubt that the speed of the pedal is many times faster than what you estimate. Assume you are standing on one pedal on the ball of your foot and somehow the pin in the chain link just forward of the rear sprocket were to be pulled. I'm sure the chain would accelerate much faster than 1G and travel forward at a significant speed. I have seen such chains wrap around the front derailleur and tear it of before the riders foot hit the bottom of the stroke. > If the chain accelerates at free-fall velocity (it may go much > faster), then it will cover the whole half an inch involved in a > skip (0.04167 feet) in 0.051 seconds, about a twentieth of a second. Your assumptions don't fit the experience I have with chain skip. > But the chain would be traveling at only the pathetically slow speed > of 1.637 feet per second, about 1.1 mph. I take it you haven't experienced this phenomenon or you wouldn't propose such results as meaningful. > The chain can easily go faster if a force greater than gravity is > applied to a mass, but that involves accelerating two legs, the > crank, and the whole chain to the kind of speed achieved with a > rubber band and a short section of chain. I think that elastic > storage is the best hope As I said previously, the stroke of a chain skip is about a quarter inch of pedal travel. That distance is available below the ankle with insignificant inertia, but it is even more available in the sway of the BB under heavy pedal pressure. > My quick test with a rubber band showed that it will fling a few > inches of chain spitwad-style about fifty feet down the driveway in > about a second--that's close to two orders of magnitude more > acceleration, but it's from a miniature bow-and-arrow with > considerably more than half an inch of draw. The rubber band is an easy way to discover whether you can cause disengagement. As I said, we can argue about how strong a rubber band is appropriate later. > I agree that _if_ there's a lot of usable force stored elastically > in the upper run and frame, then the short section of the chain may > accelerate to a high speed relative to the gear tooth half an inch > away. But I don't know how to measure this speed practically or > predict it theoretically. What you mean "upper run"? Just press down on a pedal in the forward position and notice how much elasticity there is to that load. That can spring back in milliseconds. > So all that I can say is that the actual speed in a chain skip may > be less than, equal to, or greater than the surprisingly large > acceleration that a rubber band imparts to a short section of free > chain. Forget about "actual speed" and get on with the possibility of disengagement, or are you dodging. > (Obviously, lengthening the short chain to run it around the two > idler pulleys would add the mass of the pulleys, their arms, and the > additional length of the chain, which the skip has to yank and > accelerate in the real world.) > I have no idea how well 40+ multi-piece chain links will store and > release energy at the level of a rider pushing on one pedal. > That's why I'm still curious about calculations. It seems to be a > much trickier situation than I imagined when I was thinking of my > original whack-it-with-hammer test or when I was admiring your more > elegant rubber-band test. I have no idea what model you would use to develop equations. That is a study in itself. Jobst Brandt =20                                                     Date: 29 Jun 2007 12:20:25 From: Subject: Re: Safe to lengthen a chain? On 29 Jun 2007 04:36:48 GMT, jobst.brandt@stanfordalumni.org wrote: [snip] >I am familiar with chain skip and am certain that it occurs >in less than 10ms, or as I said, the sound of a snap of the fingers. [snip] Dear Jobst, Isn't the sound just the impact, not the time from skipping off one set of teeth to the next? Cheers, Carl Fogel                                                       Date: 29 Jun 2007 18:37:38 From: Subject: Re: Safe to lengthen a chain? Carl Fogel writes: >> I am familiar with chain skip and am certain that it occurs in less >> than 10ms, or as I said, the sound of a snap of the fingers. > [snip] > Isn't the sound just the impact, not the time from skipping off one > set of teeth to the next? It is the entire event. Breaking loose is the beginning of the sound and landing the end. A skipping chain emits several sounds that, to the human ear, are almost simultaneous. It could be that the re-engagement is so loud that the snap of the derailleur is masked but so what? The impact is part is the one of interest in opening a SuperLink. Jobst Brandt                                         Date: 27 Jun 2007 22:18:36 From: Subject: Re: Safe to lengthen a chain? On 28 Jun 2007 03:54:59 GMT, jobst.brandt@stanfordalumni.org wrote: >Carl Fogel writes: > >> But if a sharp rap does open a quick-connect, I'll have to wonder >> why they don't fly apart when riders are jolting down bumpy hills. A >> quick-connect just about to enter or leave the front sprocket has >> the whole chain run banging it forward to compress things, and it >> has a good chance of being in that position during a year's riding. > >Looking for a way to emulate the link separation I experienced, I >believe a good method would be to attach one inner chain link to a >rubber band hung from a roof like metal strut, and attach about three >inches of chain to that link using a clean SuperLink. After pressing >the SuperLink side plates together manually before pulling down on the >loose end of chain, allowing it to spring upward to strike the ceiling >a few times may release the cover plate and the rest is history. > >Jobst Brandt Dear Jobst, I'm not sure if it matters whether the chain is in motion or is struck by a hammer, but the idea is intriguing. Chain speed at 60~90 rpm on a 53-tooth is only about 1.5 to 2.2 mph, but the downward snap of a chain link popping down into place may be much higher. In any case, what worries me is that using only a few links might not provide as much bump. If the link doesn't open, it could be because in real life something like 40 links on the lower chain run are lined up behind the target quick-connect. Maybe a monster rubberband will bang 40 links or so up into the ceiling, but I'm thinking of modifying your idea by pulling a 40 link chain section (with one link ahead of a quick connect) laid on a table and heading toward a pair of holes in a hefty chunk of metal with a string looped through the end roller so that the string doesn't cushion things. A heavier and heavier weight on the string (or high test fishing line) could accelerate the chain. 40 links qc = x metal _ _ _ _ _ _ _ _ string barrier                                           Date: 28 Jun 2007 04:32:40 From: Subject: Re: Safe to lengthen a chain? Carl Fogel writes: >>> But if a sharp rap does open a quick-connect, I'll have to wonder >>> why they don't fly apart when riders are jolting down bumpy hills. >>> A quick-connect just about to enter or leave the front sprocket >>> has the whole chain run banging it forward to compress things, and >>> it has a good chance of being in that position during a year's >>> riding. >> Looking for a way to emulate the link separation I experienced, I >> believe a good method would be to attach one inner chain link to a >> rubber band hung from a roof like metal strut, and attach about >> three inches of chain to that link using a clean SuperLink. After >> pressing the SuperLink side plates together manually before pulling >> down on the loose end of chain, allowing it to spring upward to >> strike the ceiling a few times may release the cover plate and the >> rest is history. > I'm not sure if it matters whether the chain is in motion or is > struck by a hammer, but the idea is intriguing. > Chain speed at 60~90 rpm on a 53-tooth is only about 1.5 to 2.2 mph, > but the downward snap of a chain link popping down into place may be > much higher. > In any case, what worries me is that using only a few links might > not provide as much bump. If the link doesn't open, it could be > because in real life something like 40 links on the lower chain run > are lined up behind the target quick-connect. Only a few links are in a straight line between derailleur and sprocket. A longer piece might bias the experiment toward opening the link more than one that is about the right length. > Maybe a monster rubber band will bang 40 links or so up into the > ceiling, but I'm thinking of modifying your idea by pulling a 40 > link chain section (with one link ahead of a quick connect) laid on > a table and heading toward a pair of holes in a hefty chunk of metal > with a string looped through the end roller so that the string > doesn't cushion things. A heavier and heavier weight on the string > (or high test fishing line) could accelerate the chain. Don't invalidate the experiment from the start by doing that. My bicycle has 2.5 inches straight chain between derailleur idler and the 13t sprocket. The links around the corner don't count. > 40 links qc =3D x metal _ _ _ _ _ _ _ _ string barrier >                                             Date: 27 Jun 2007 22:53:11 From: Subject: Re: Safe to lengthen a chain? On 28 Jun 2007 04:32:40 GMT, jobst.brandt@stanfordalumni.org wrote: >Carl Fogel writes: > >>>> But if a sharp rap does open a quick-connect, I'll have to wonder >>>> why they don't fly apart when riders are jolting down bumpy hills. >>>> A quick-connect just about to enter or leave the front sprocket >>>> has the whole chain run banging it forward to compress things, and >>>> it has a good chance of being in that position during a year's >>>> riding. > >>> Looking for a way to emulate the link separation I experienced, I >>> believe a good method would be to attach one inner chain link to a >>> rubber band hung from a roof like metal strut, and attach about >>> three inches of chain to that link using a clean SuperLink. After >>> pressing the SuperLink side plates together manually before pulling >>> down on the loose end of chain, allowing it to spring upward to >>> strike the ceiling a few times may release the cover plate and the >>> rest is history. > >> I'm not sure if it matters whether the chain is in motion or is >> struck by a hammer, but the idea is intriguing. > >> Chain speed at 60~90 rpm on a 53-tooth is only about 1.5 to 2.2 mph, >> but the downward snap of a chain link popping down into place may be >> much higher. > >> In any case, what worries me is that using only a few links might >> not provide as much bump. If the link doesn't open, it could be >> because in real life something like 40 links on the lower chain run >> are lined up behind the target quick-connect. > >Only a few links are in a straight line between derailleur and >sprocket. A longer piece might bias the experiment toward opening the >link more than one that is about the right length. > >> Maybe a monster rubber band will bang 40 links or so up into the >> ceiling, but I'm thinking of modifying your idea by pulling a 40 >> link chain section (with one link ahead of a quick connect) laid on >> a table and heading toward a pair of holes in a hefty chunk of metal >> with a string looped through the end roller so that the string >> doesn't cushion things. A heavier and heavier weight on the string >> (or high test fishing line) could accelerate the chain. > >Don't invalidate the experiment from the start by doing that. My >bicycle has 2.5 inches straight chain between derailleur idler and the >13t sprocket. The links around the corner don't count. > >> 40 links qc = x metal _ _ _ _ _ _ _ _ string barrier >>                             Date: 26 Jun 2007 13:17:15 From: Tom Nakashima Subject: Re: Safe to lengthen a chain? <carlfogel@comcast.net > wrote in message news:12r2839u86kfua3gg8lfvg2mlh4kuc7jse@4ax.com... > On 26 Jun 2007 19:40:46 GMT, jobst.brandt@stanfordalumni.org wrote: > >>Carl Fogel writes: >> >>>>>>>> I haven't had a chain separate in use except the time I used a >>>>>>>> PowerLink. >> >>>>>>> I'm curious, how did your chain separate when you used a >>>>>>> PowerLink? >> >>>>>> That event has been retold here a few times. >> >>>>>> After installing a new chain on used sprockets, the chain skipped >>>>>> occasionally on the 13t sprocket. One of these skips occurred at >>>>>> the precise moment before the PowerLink went into engagement and >>>>>> the inertia of following links compressed the chain enough to >>>>>> separate the link (after I had ridden more than 10 miles). >> >>>>> I haven't heard this before, and can't imagine the PowerLink >>>>> disengaging under tension even when rolling over such a small >>>>> diameter as a 13t sprocket. Cyclist have used the PowerLink >>>>> connector on 12t or even 11t sprockets without failure. The only >>>>> way I could possibly see the PowerLink disengaging, would be >>>>> backpedaling and having the chain getting hung-up to compress the >>>>> PowerLink enough to become disengaged. >> >>>> Slow down. Re-read the description of PowerLink separation. It >>>> did not separate while that part of the chain was in tension! >> >>> Given gravity, when is any part of a bicycle chain not in at least >>> some tension? >> >>INERTIA! Read the item! As the chain was going into engagement >>precisely at the moment the PowerLink approached the 13t sprocket, the >>chain skipped. Chain skip accelerates the chain to move forward in a >>few milliseconds and stops as the chain falls back into engagement. >>Inertia of the following chain compressed the PowerLink enough to make >>it fall apart. > > [snip] > > Dear Jobst, > > I'm still puzzled. > > Are you saying that a metal chain constantly slows down as it is > _pulled_ onto a gear? > > Cheers, > > Carl Fogel Ok, I reread it. Shifting from a bigger sprocket onto the 13t...(friction shifters I take it?) It's possible, but I'm still not convinced here, because I don't think a millisecond is enough time for the PowerLink to disengage. But you got my curiosity enough that I have just the bike to duplicate that theory on a bike stand. With friction shifters, one can put it in a skip mode somewhere in-between the 13t cog. -tom                               Date: 26 Jun 2007 20:40:07 From: Subject: Re: Safe to lengthen a chain? Tom Nakashima writes: >>>>>> I haven't heard this before, and can't imagine the PowerLink >>>>>> disengaging under tension even when rolling over such a small >>>>>> diameter as a 13t sprocket. Cyclist have used the PowerLink >>>>>> connector on 12t or even 11t sprockets without failure. The >>>>>> only way I could possibly see the PowerLink disengaging, would >>>>>> be backpedaling and having the chain getting hung-up to >>>>>> compress the PowerLink enough to become disengaged. >>>>> Slow down. Re-read the description of PowerLink separation. It >>>>> did not separate while that part of the chain was in tension! >>>> Given gravity, when is any part of a bicycle chain not in at >>>> least some tension? >>> INERTIA! Read the item! As the chain was going into engagement >>> precisely at the moment the PowerLink approached the 13t sprocket, >>> the chain skipped. Chain skip accelerates the chain to move >>> forward in a few milliseconds and stops as the chain falls back >>> into engagement. Inertia of the following chain compressed the >>> PowerLink enough to make it fall apart. >> I'm still puzzled. >> Are you saying that a metal chain constantly slows down as it is >> _pulled_ onto a gear? > OK, I reread it. Shifting from a bigger sprocket onto the > 13t...(friction shifters I take it?) It's possible, but I'm still > not convinced here, because I don't think a millisecond is enough > time for the PowerLink to disengage. STOP!!!! Please explain what you don't understand about riding in one gear and having the chain skip. What in hell does friction shifting have to do with chain skip? This is getting ridiculous. New chains skip on worn sprockets. I have indexed shifting. > But you got my curiosity enough that I have just the bike to > duplicate that theory on a bike stand. With friction shifters, one > can put it in a skip mode somewhere in-between the 13t cog. I doubt that you could repeat that unless you rode many miles with a clean new chain of that type using even ten PowerLink connectors of chain segment to increase the probability of a skip at the proper moment. You would also need a worn sprocket that produced skips only under high pedal torque. This also has nothing to do with a 13t sprocket. It could just as well been one of any other size. It just happens that smaller sprockets wear faster and my 13t had just gotten to the skipping threshold. Jobst Brandt                                 Date: 26 Jun 2007 13:46:44 From: Tom Nakashima Subject: Re: Safe to lengthen a chain? <jobst.brandt@stanfordalumni.org > wrote in message news:468179a7$0$14131$742ec2ed@news.sonic.net... > Tom Nakashima writes: > >>>>>>> I haven't heard this before, and can't imagine the PowerLink >>>>>>> disengaging under tension even when rolling over such a small >>>>>>> diameter as a 13t sprocket. Cyclist have used the PowerLink >>>>>>> connector on 12t or even 11t sprockets without failure. The >>>>>>> only way I could possibly see the PowerLink disengaging, would >>>>>>> be backpedaling and having the chain getting hung-up to >>>>>>> compress the PowerLink enough to become disengaged. > >>>>>> Slow down. Re-read the description of PowerLink separation. It >>>>>> did not separate while that part of the chain was in tension! > >>>>> Given gravity, when is any part of a bicycle chain not in at >>>>> least some tension? > >>>> INERTIA! Read the item! As the chain was going into engagement >>>> precisely at the moment the PowerLink approached the 13t sprocket, >>>> the chain skipped. Chain skip accelerates the chain to move >>>> forward in a few milliseconds and stops as the chain falls back >>>> into engagement. Inertia of the following chain compressed the >>>> PowerLink enough to make it fall apart. > >>> I'm still puzzled. > >>> Are you saying that a metal chain constantly slows down as it is >>> _pulled_ onto a gear? > >> OK, I reread it. Shifting from a bigger sprocket onto the >> 13t...(friction shifters I take it?) It's possible, but I'm still >> not convinced here, because I don't think a millisecond is enough >> time for the PowerLink to disengage. > > STOP!!!! > > Please explain what you don't understand about riding in one gear and > having the chain skip. What in hell does friction shifting have to do > with chain skip? This is getting ridiculous. New chains skip on worn > sprockets. I have indexed shifting. Ok, thought you were using friction shifters, in shifting down to the 13t but not having it engaged all the way. That's what I thought when you said skipping? > >> But you got my curiosity enough that I have just the bike to >> duplicate that theory on a bike stand. With friction shifters, one >> can put it in a skip mode somewhere in-between the 13t cog. > > I doubt that you could repeat that unless you rode many miles with a > clean new chain of that type using even ten PowerLink connectors of > chain segment to increase the probability of a skip at the proper > moment. You would also need a worn sprocket that produced skips only > under high pedal torque. This also has nothing to do with a 13t > sprocket. It could just as well been one of any other size. It just > happens that smaller sprockets wear faster and my 13t had just gotten > to the skipping threshold. > > Jobst Brandt Not sure why the experiment couldn't be duplicated? If that's the case, how would you know if the PowerLink was a defect? -tom                                   Date: 27 Jun 2007 00:39:16 From: Subject: Re: Safe to lengthen a chain? Tom Nakashima writes: >>>> I'm still puzzled. >>>> Are you saying that a metal chain constantly slows down as it is >>>> _pulled_ onto a gear? >>> OK, I reread it. Shifting from a bigger sprocket onto the >>> 13t...(friction shifters I take it?) It's possible, but I'm still >>> not convinced here, because I don't think a millisecond is enough >>> time for the PowerLink to disengage. >> STOP!!!! >> Please explain what you don't understand about riding in one gear >> and having the chain skip. What in hell does friction shifting >> have to do with chain skip? This is getting ridiculous. New >> chains skip on worn sprockets. I have indexed shifting. > OK, thought you were using friction shifters, in shifting down to > the 13t but not having it engaged all the way. That's what I > thought when you said skipping? Did you see anything about shifting gears in what I wrote? Did I say anything about gear engagement? Did I say I had ridden more than 10 miles before the incident that occurred when I stood up in the gear and the chain skipped? Did I not explain that it is the inertia of the following chain that compressed the link? Stop and think about this a moment. I'm not new to bicycling so don't create any scenarios that might have missed my observation in this chain problem. >>> But you got my curiosity enough that I have just the bike to >>> duplicate that theory on a bike stand. With friction shifters, one >>> can put it in a skip mode somewhere in-between the 13t cog. >> I doubt that you could repeat that unless you rode many miles with >> a clean new chain of that type using even ten PowerLink connectors >> of chain segment to increase the probability of a skip at the >> proper moment. You would also need a worn sprocket that produced >> skips only under high pedal torque. This also has nothing to do >> with a 13t sprocket. It could just as well been one of any other >> size. It just happens that smaller sprockets wear faster and my >> 13t had just gotten to the skipping threshold. > Not sure why the experiment couldn't be duplicated? If that's the > case, how would you know if the PowerLink was a defect? Try to imagine how unusual it is that the forward roller of the PowerLink was positioned on the entry to the sprocket so that when the chain skipped, the advancing length of following chain, inertially pushed the chain forward against the relatively immobile PowerLink while the chain line was just right to cause the cover plate to be deflected inward enough to clear the locking contour of the stepped release slot. I reported this because it was such an unusual mechanical coincidence of events but realized that no one understood or cared what occurred from the silence that followed. Jobst Brandt                                     Date: 28 Jun 2007 10:50:10 From: Paul Myron Hobson Subject: Re: Safe to lengthen a chain? jobst.brandt@stanfordalumni.org wrote: > Try to imagine how unusual it is that the forward roller of the > PowerLink was positioned on the entry to the sprocket so that when the > chain skipped, the advancing length of following chain, inertially > pushed the chain forward against the relatively immobile PowerLink... Jobst, I'm can't figure out exactly what makes you so certain of the position of the PowerLink before/during its separation? Location of the chain as it was resting on the drive train? You happen to have been watching it? Something else? It seems that if you stopped pedaling immediately, the chain would no longer move relative to the chainrings, and its position could be reconstructed that way. Is that what you're going off of? \\paul                                       Date: 28 Jun 2007 18:26:04 From: Subject: Re: Safe to lengthen a chain? Paul Myron Hobson writes: >> Try to imagine how unusual it is that the forward roller of the >> PowerLink was positioned on the entry to the sprocket so that when >> the chain skipped, the advancing length of following chain, >> inertially pushed the chain forward against the relatively immobile >> PowerLink... > Jobst, > I'm can't figure out exactly what makes you so certain of the > position of the PowerLink before/during its separation? Location of > the chain as it was resting on the drive train? You happen to have > been watching it? The chain skipped and almost immediately came off the chainwheel. Had the SuperLink been ahead of the chainwheel and opened, the chain could not have skipped, being under no tension. Had the Super Link been on the slack run of the chain, it could not be compressed, it hanging in a catenary curve... and I would have had chain drive until the open end of the chain came off the sprocket. Beyond that, had the link separated before the derailleur, I would have had multiple skips because the chain would no longer have been suitably tensioned to remain in engagement with a sprocket that tended to skip. > Something else? > It seems that if you stopped pedaling immediately, the chain would no > longer move relative to the chainrings, and its position could be > reconstructed that way. Is that what you're going off of? Why would I stop pedaling when climbing a grade and desiring to get to my destination. As I said, the chain rolled off onto the road almost immediately after the skip. Had I been standing, I might have had other problems of staying on the bicycle. Jobst Brandt                                         Date: 28 Jun 2007 21:25:46 From: Sandy Subject: Re: Safe to lengthen a chain? Dans le message de news:4683fd3c$0$14088$742ec2ed@news.sonic.net, jobst.brandt@stanfordalumni.org <jobst.brandt@stanfordalumni.org > a réfléchi, et puis a déclaré : > Paul Myron Hobson writes: > >>> Try to imagine how unusual it is that the forward roller of the >>> PowerLink was positioned on the entry to the sprocket so that when >>> the chain skipped, the advancing length of following chain, >>> inertially pushed the chain forward against the relatively immobile >>> PowerLink... > >> Jobst, > >> I'm can't figure out exactly what makes you so certain of the >> position of the PowerLink before/during its separation? Location of >> the chain as it was resting on the drive train? You happen to have >> been watching it? > > The chain skipped and almost immediately came off the chainwheel. Had > the SuperLink been ahead of the chainwheel and opened, the chain could > not have skipped, being under no tension. Had the Super Link been on > the slack run of the chain, it could not be compressed, it hanging in > a catenary curve... and I would have had chain drive until the open > end of the chain came off the sprocket. > > Beyond that, had the link separated before the derailleur, I would > have had multiple skips because the chain would no longer have been > suitably tensioned to remain in engagement with a sprocket that tended > to skip. > >> Something else? > >> It seems that if you stopped pedaling immediately, the chain would no >> longer move relative to the chainrings, and its position could be >> reconstructed that way. Is that what you're going off of? > > Why would I stop pedaling when climbing a grade and desiring to get to > my destination. As I said, the chain rolled off onto the road almost > immediately after the skip. Had I been standing, I might have had > other problems of staying on the bicycle. > > Jobst Brandt If you weren't otherwise notorious, and a stranger read what you wrote, he might be inclined to surmise you have been on the bottle this last week. Those who know your notoriety will have to surmise that you are being laugably silly just to irk readers.                                         Date: 28 Jun 2007 14:42:14 From: Paul Myron Hobson Subject: Re: Safe to lengthen a chain? > Paul Myron Hobson writes: >> It seems that if you stopped pedaling immediately, the chain would no >> longer move relative to the chainrings, and its position could be >> reconstructed that way. Is that what you're going off of? Jobst Brandt wrote: > Why would I stop pedaling when climbing a grade and desiring to get to > my destination. I was talking after the break occurred. If my chain fell off, the first thing I do would be to stop pedaling and stop, which appears to be what you did. > As I said, the chain rolled off onto the road almost > immediately after the skip. This thread is ~150 posts long. Sorry I missed that detail. Sheesh.                                     Date: 27 Jun 2007 10:31:11 From: Tom Nakashima Subject: Re: Safe to lengthen a chain? <jobst.brandt@stanfordalumni.org > wrote in message news:4681b1b4$0$14130$742ec2ed@news.sonic.net... > > Try to imagine how unusual it is that the forward roller of the > PowerLink was positioned on the entry to the sprocket so that when the > chain skipped, the advancing length of following chain, inertially > pushed the chain forward against the relatively immobile PowerLink > while the chain line was just right to cause the cover plate to be > deflected inward enough to clear the locking contour of the stepped > release slot. I reported this because it was such an unusual > mechanical coincidence of events but realized that no one understood > or cared what occurred from the silence that followed. > > Jobst Brandt That was good Jobst: "The magic PowerLink". I'll rank this one right up there with the Warren Commission Report of Oswald's magic bullet. -tom                             Date: 26 Jun 2007 19:58:37 From: Subject: Re: Safe to lengthen a chain? Carl Fogel writes: >>>>>>>> I haven't had a chain separate in use except the time I used >>>>>>>> a PowerLink. >>>>>>> I'm curious, how did your chain separate when you used a >>>>>>> PowerLink? >>>>>> That event has been retold here a few times. >>>>>> After installing a new chain on used sprockets, the chain >>>>>> skipped occasionally on the 13t sprocket. One of these skips >>>>>> occurred at the precise moment before the PowerLink went into >>>>>> engagement and the inertia of following links compressed the >>>>>> chain enough to separate the link (after I had ridden more than >>>>>> 10 miles). >>>>> I haven't heard this before, and can't imagine the PowerLink >>>>> disengaging under tension even when rolling over such a small >>>>> diameter as a 13t sprocket. Cyclist have used the PowerLink >>>>> connector on 12t or even 11t sprockets without failure. The only >>>>> way I could possibly see the PowerLink disengaging, would be >>>>> backpedaling and having the chain getting hung-up to compress >>>>> the PowerLink enough to become disengaged. >>>> Slow down. Re-read the description of PowerLink separation. It >>>> did not separate while that part of the chain was in tension! >>> Given gravity, when is any part of a bicycle chain not in at least >>> some tension? >> INERTIA! Read the item! As the chain was going into engagement >> precisely at the moment the PowerLink approached the 13t sprocket, >> the chain skipped. Chain skip accelerates the chain to move >> forward in a few milliseconds and stops as the chain falls back >> into engagement. Inertia of the following chain compressed the >> PowerLink enough to make it fall apart. > I'm still puzzled. > Are you saying that a metal chain constantly slows down as it is > _pulled_ onto a gear? Are you reading what I write??? I said I installed a new chain on used sprockets and found that the chain skipped on the 13t sprocket as I rode to work. One of those skips occurred just as the PowerLink approached engagement with that 13t sprocket. Chain skip rapidly accelerates the chain (in a couple of milliseconds) for the duration of a single link (1/2" to be exact), after which it slows to normal chain speed. That deceleration caused the following chain, by its inertia, to compress the PowerLink and disengage it. With each iteration I'm adding words that seem to make no difference to you and Tom. What is missing? ... or maybe you are pulling my leg, so to speak. Jobst Brandt                               Date: 26 Jun 2007 15:48:38 From: Subject: Re: Safe to lengthen a chain? On 26 Jun 2007 19:58:37 GMT, jobst.brandt@stanfordalumni.org wrote: >Carl Fogel writes: > >>>>>>>>> I haven't had a chain separate in use except the time I used >>>>>>>>> a PowerLink. > >>>>>>>> I'm curious, how did your chain separate when you used a >>>>>>>> PowerLink? > >>>>>>> That event has been retold here a few times. > >>>>>>> After installing a new chain on used sprockets, the chain >>>>>>> skipped occasionally on the 13t sprocket. One of these skips >>>>>>> occurred at the precise moment before the PowerLink went into >>>>>>> engagement and the inertia of following links compressed the >>>>>>> chain enough to separate the link (after I had ridden more than >>>>>>> 10 miles). > >>>>>> I haven't heard this before, and can't imagine the PowerLink >>>>>> disengaging under tension even when rolling over such a small >>>>>> diameter as a 13t sprocket. Cyclist have used the PowerLink >>>>>> connector on 12t or even 11t sprockets without failure. The only >>>>>> way I could possibly see the PowerLink disengaging, would be >>>>>> backpedaling and having the chain getting hung-up to compress >>>>>> the PowerLink enough to become disengaged. > >>>>> Slow down. Re-read the description of PowerLink separation. It >>>>> did not separate while that part of the chain was in tension! > >>>> Given gravity, when is any part of a bicycle chain not in at least >>>> some tension? > >>> INERTIA! Read the item! As the chain was going into engagement >>> precisely at the moment the PowerLink approached the 13t sprocket, >>> the chain skipped. Chain skip accelerates the chain to move >>> forward in a few milliseconds and stops as the chain falls back >>> into engagement. Inertia of the following chain compressed the >>> PowerLink enough to make it fall apart. > >> I'm still puzzled. > >> Are you saying that a metal chain constantly slows down as it is >> _pulled_ onto a gear? > >Are you reading what I write??? > >I said I installed a new chain on used sprockets and found that the >chain skipped on the 13t sprocket as I rode to work. One of those >skips occurred just as the PowerLink approached engagement with that >13t sprocket. Chain skip rapidly accelerates the chain (in a couple >of milliseconds) for the duration of a single link (1/2" to be exact), >after which it slows to normal chain speed. That deceleration caused >the following chain, by its inertia, to compress the PowerLink and >disengage it. > >With each iteration I'm adding words that seem to make no difference >to you and Tom. What is missing? > >... or maybe you are pulling my leg, so to speak. > >Jobst Brandt Dear Jobst, Drop the paranoia. Tom and I are just curious about what seems to be an odd claim. I can't recall anyone else mentioning this problem. Your theory is that your chain accelerated momentarily with a chain skip at the rear cog. Then the whole chain slowed down enough to compress a two-piece PowerLink on the lower run to where some other force pulled the link apart enough that it failed to re-engage and then worked loose. Right? The lower run of chain would have to bang the power link rearward hard enough against the initial rear tooth to move the whole lower run a full pin's length. If so, you should be able to separate a PowerLink on a reasonably adjusted derailleur chain by tapping the lower pulley with a hammer. On a fixie, things would seem rather more difficult. Two other possibilities would be that the link was defective or not quite properly installed. You can insist that it was not defective and that you're certain that it was properly installed, of course, but you can hardly blame people for wondering why no one else seems to have suffered this problem. I've ridden skipping chains with various quick connect links for considerably more than ten miles without my chain flying apart, and I suspect that many other riders on both derailleurs and fixies have, too. If I'm mistaken and this is a common problem, I'm sure that other posters will chime in with tales of quick-connect links flying apart when chains skip. Cheers, Carl Fogel                                 Date: 26 Jun 2007 22:27:26 From: A Muzi Subject: Re: Safe to lengthen a chain? > On 26 Jun 2007 19:58:37 GMT, jobst.brandt@stanfordalumni.org wrote: >> Carl Fogel writes: >>>>>>>>>> I haven't had a chain separate in use except the time I used >>>>>>>>>> a PowerLink. >>>>>>>>> I'm curious, how did your chain separate when you used a >>>>>>>>> PowerLink? >>>>>>>> That event has been retold here a few times. >>>>>>>> After installing a new chain on used sprockets, the chain >>>>>>>> skipped occasionally on the 13t sprocket. One of these skips >>>>>>>> occurred at the precise moment before the PowerLink went into >>>>>>>> engagement and the inertia of following links compressed the >>>>>>>> chain enough to separate the link (after I had ridden more than >>>>>>>> 10 miles). >>>>>>> I haven't heard this before, and can't imagine the PowerLink >>>>>>> disengaging under tension even when rolling over such a small >>>>>>> diameter as a 13t sprocket. Cyclist have used the PowerLink >>>>>>> connector on 12t or even 11t sprockets without failure. The only >>>>>>> way I could possibly see the PowerLink disengaging, would be >>>>>>> backpedaling and having the chain getting hung-up to compress >>>>>>> the PowerLink enough to become disengaged. >>>>>> Slow down. Re-read the description of PowerLink separation. It >>>>>> did not separate while that part of the chain was in tension! >>>>> Given gravity, when is any part of a bicycle chain not in at least >>>>> some tension? >>>> INERTIA! Read the item! As the chain was going into engagement >>>> precisely at the moment the PowerLink approached the 13t sprocket, >>>> the chain skipped. Chain skip accelerates the chain to move >>>> forward in a few milliseconds and stops as the chain falls back >>>> into engagement. Inertia of the following chain compressed the >>>> PowerLink enough to make it fall apart. >>> I'm still puzzled. >>> Are you saying that a metal chain constantly slows down as it is >>> _pulled_ onto a gear? >> Are you reading what I write??? >> >> I said I installed a new chain on used sprockets and found that the >> chain skipped on the 13t sprocket as I rode to work. One of those >> skips occurred just as the PowerLink approached engagement with that >> 13t sprocket. Chain skip rapidly accelerates the chain (in a couple >> of milliseconds) for the duration of a single link (1/2" to be exact), >> after which it slows to normal chain speed. That deceleration caused >> the following chain, by its inertia, to compress the PowerLink and >> disengage it. >> With each iteration I'm adding words that seem to make no difference >> to you and Tom. What is missing? >> ... or maybe you are pulling my leg, so to speak. carlfogel@comcast.net wrote: -snip- > Your theory is that your chain accelerated momentarily with a chain > skip at the rear cog. Then the whole chain slowed down enough to > compress a two-piece PowerLink on the lower run to where some other > force pulled the link apart enough that it failed to re-engage and > then worked loose. > Right? > The lower run of chain would have to bang the power link rearward hard > enough against the initial rear tooth to move the whole lower run a > full pin's length. > If so, you should be able to separate a PowerLink on a reasonably > adjusted derailleur chain by tapping the lower pulley with a hammer. > On a fixie, things would seem rather more difficult. > Two other possibilities would be that the link was defective or not > quite properly installed. > You can insist that it was not defective and that you're certain that > it was properly installed, of course, but you can hardly blame people > for wondering why no one else seems to have suffered this problem. > I've ridden skipping chains with various quick connect links for > considerably more than ten miles without my chain flying apart, and I > suspect that many other riders on both derailleurs and fixies have, > too. > If I'm mistaken and this is a common problem, I'm sure that other > posters will chime in with tales of quick-connect links flying apart > when chains skip. I suspect if you watch a new chain trying to engage a worn small cog all will be revealed. I also got the impression earlier there was some confusion with the term 'skip' which is _not_ a lateral shift alignment issue but rather an in-line inability of the chain to seat in the root of a cog's tooth. -- Andrew Muzi www.yellowjersey.org Open every day since 1 April, 1971                                 Date: 27 Jun 2007 01:04:24 From: Subject: Re: Safe to lengthen a chain? Carl Fogel writes: >>>>> Given gravity, when is any part of a bicycle chain not in at >>>>> least some tension? >>>> INERTIA! Read the item! As the chain was going into engagement >>>> precisely at the moment the PowerLink approached the 13t >>>> sprocket, the chain skipped. Chain skip accelerates the chain to >>>> move forward in a few milliseconds and stops as the chain falls >>>> back into engagement. Inertia of the following chain compressed >>>> the PowerLink enough to make it fall apart. >>> I'm still puzzled. >>> Are you saying that a metal chain constantly slows down as it is >>> _pulled_ onto a gear? >>Are you reading what I write??? >> I said I installed a new chain on used sprockets and found that the >> chain skipped on the 13t sprocket as I rode to work. One of those >> skips occurred just as the PowerLink approached engagement with >> that 13t sprocket. Chain skip rapidly accelerates the chain (in a >> couple of milliseconds) for the duration of a single link (1/2" to >> be exact), after which it slows to normal chain speed. That >> deceleration caused the following chain, by its inertia, to >> compress the PowerLink and disengage it. >> With each iteration I'm adding words that seem to make no >> difference to you and Tom. What is missing? >> ... or maybe you are pulling my leg, so to speak. > Drop the paranoia. > Tom and I are just curious about what seems to be an odd claim. > I can't recall anyone else mentioning this problem. That's why it is such an oddity. As I explained to Tom, he has little chance of repeating the effect, even with multiple PowerLinks in his chain. > Your theory is that your chain accelerated momentarily with a chain > skip at the rear cog. Then the whole chain slowed down enough to > compress a two-piece PowerLink on the lower run to where some other > force pulled the link apart enough that it failed to re-engage and > then worked loose. It's not a theory. It occurred as I described it. The link lay undamaged on the road with its two parts less than a foot apart. > Right? > The lower run of chain would have to bang the power link rearward > hard enough against the initial rear tooth to move the whole lower > run a full pin's length. Imagine the run of the chain between the upper idler of the derailleur advancing from a chain skip. That would be a half inch advance in the snap of a finger (or the cracking sound of a chine skipping over one pitch) occurring in a couple of milliseconds. That's about 100 times as fast as the chain moves in a 50t-13t gear with a cadence of 60. > If so, you should be able to separate a PowerLink on a reasonably > adjusted derailleur chain by tapping the lower pulley with a hammer. > On a fixie, things would seem rather more difficult. I don't think you are able to visualize what occurred. I think I stated repeatedly that the PowerLink had to be at engagement with the rear sprocket to be inertially subject to this effect. > Two other possibilities would be that the link was defective or not > quite properly installed. I rode ten miles up nd down fairly steep grades up to that point. Your scenario assumes I am a klutz, a liar, or a day dreamer who doesn't know what makes a bicycle move. > You can insist that it was not defective and that you're certain > that it was properly installed, of course, but you can hardly blame > people for wondering why no one else seems to have suffered this > problem. As I explained, I reinstalled the link and rode it for many miles (200+) after that. You are grasping for straws where there are none. Just analyze the situation seriously instead of inventing spurious scenarios that have been ruled out by what I wrote. > I've ridden skipping chains with various quick connect links for > considerably more than ten miles without my chain flying apart, and > I suspect that many other riders on both derailleurs and fixies > have, too. As I said, it is highly unlikely that this can occur, but as many things on a bicycle, they seem to occur on my bicycle at the outset of the use of a certain piece of equipment. How many internally lugged steel forks have you seen fail. Mine did so twice and the second time made me realize it was not a quirk but rather a design failure because the internal lug cannot be feathered and causes a sharp stress concentration at the end of the internal lug. It was then that I realized Cinelli did bicycling a great disservice by introducing his "elegant sloping fork crown". Masi had it right, both because the crown is durable and because it weighs about 2/3 of a Cinelli crown. My engineering life is full of these experiences, and often I get to hear that it couldn't happen because it hasn't occurred in the critic's experience. > If I'm mistaken and this is a common problem, I'm sure that other > posters will chime in with tales of quick-connect links flying apart > when chains skip. You are attempting to construct this as a common problem. It is not. Just because it is uncommon, doesn't mean it didn't occur. It seems as that is toward what you are driving. Jobst Brandt                                   Date: 26 Jun 2007 20:22:49 From: Subject: Re: Safe to lengthen a chain? On 27 Jun 2007 01:04:24 GMT, jobst.brandt@stanfordalumni.org wrote: >Carl Fogel writes: > >>>>>> Given gravity, when is any part of a bicycle chain not in at >>>>>> least some tension? > >>>>> INERTIA! Read the item! As the chain was going into engagement >>>>> precisely at the moment the PowerLink approached the 13t >>>>> sprocket, the chain skipped. Chain skip accelerates the chain to >>>>> move forward in a few milliseconds and stops as the chain falls >>>>> back into engagement. Inertia of the following chain compressed >>>>> the PowerLink enough to make it fall apart. > >>>> I'm still puzzled. > >>>> Are you saying that a metal chain constantly slows down as it is >>>> _pulled_ onto a gear? > >>>Are you reading what I write??? > >>> I said I installed a new chain on used sprockets and found that the >>> chain skipped on the 13t sprocket as I rode to work. One of those >>> skips occurred just as the PowerLink approached engagement with >>> that 13t sprocket. Chain skip rapidly accelerates the chain (in a >>> couple of milliseconds) for the duration of a single link (1/2" to >>> be exact), after which it slows to normal chain speed. That >>> deceleration caused the following chain, by its inertia, to >>> compress the PowerLink and disengage it. > >>> With each iteration I'm adding words that seem to make no >>> difference to you and Tom. What is missing? > >>> ... or maybe you are pulling my leg, so to speak. > >> Drop the paranoia. > >> Tom and I are just curious about what seems to be an odd claim. > >> I can't recall anyone else mentioning this problem. > >That's why it is such an oddity. As I explained to Tom, he has little >chance of repeating the effect, even with multiple PowerLinks in his >chain. > >> Your theory is that your chain accelerated momentarily with a chain >> skip at the rear cog. Then the whole chain slowed down enough to >> compress a two-piece PowerLink on the lower run to where some other >> force pulled the link apart enough that it failed to re-engage and >> then worked loose. > >It's not a theory. It occurred as I described it. The link lay >undamaged on the road with its two parts less than a foot apart. [snip] Dear Jobst, You have an unfortunate habit of treating your theories as unassailable facts. No one doubts that your chain came apart, or that you found the two halves. What caused it to come apart is obviously theoretical. Cheers, Carl Fogel                                     Date: 27 Jun 2007 03:01:38 From: Subject: Re: Safe to lengthen a chain? Carl Fogel writes: > You have an unfortunate habit of treating your theories as > unassailable facts. > No one doubts that your chain came apart, or that you found the two > halves. > What caused it to come apart is obviously theoretical. This is not obviously theoretical and I outlined the sequence of events that preclude any of the specious scenarios that have emerged since I posted the incident. Unless you can explain another logical cause for what occurred, I think it is your theoretical position that what was obvious to me under the circumstances cannot be because no one else has had the experience. That does not sit on solid ground. I was experiencing chain skips that I recognized as a worn 13t sprocket after riding a significant distance in various gears. I had switched to my 13t sprocket once more and got a skip on the first uphill section several miles later after pedaling smoothly over a few rollers. It was not coincident with shifting, the chain had been in that gear for several rises and I use indexed shifting that stays in gear reliably. I was moving at a moderate speed of around 15mph. After the chain skipped it rolled off the chainwheel to the road as my foot got near the bottom of the stroke. I went back to the place where I estimated the chain skip occurred and found both halves of the PowerLink on the road about a foot apart, in and essentially new condition. The chain and the link were new that morning about ten miles earlier. I reassembled the chain that had no trauma and it remained that way for more than 200 miles longer. That the chain did not separate on the slack run can be deduced by how soon the chain came off. Had it been on the slack run before the derailleur, I would have gotten beyond the down-stroke before the chain rolled off onto the road. From that information, it would take some gratuitous suppositions to arrive at a different cause, but I haven't heard any that are not ruled out by the circumstances I outlined. Jobst Brandt                                       Date: 27 Jun 2007 08:52:46 From: dvt Subject: Re: Safe to lengthen a chain? jobst.brandt@stanfordalumni.org wrote: > Carl Fogel writes: > >> You have an unfortunate habit of treating your theories as >> unassailable facts. > >> No one doubts that your chain came apart, or that you found the two >> halves. > >> What caused it to come apart is obviously theoretical. > > This is not obviously theoretical and I outlined the sequence of > events that preclude any of the specious scenarios that have emerged > since I posted the incident. Unless you can explain another logical > cause for what occurred,... Is there a name for this logical fallacy? I'll try to outline it... 1. Event occurs 2. Plausible explanation invented 3. No other plausible explanation occurs to the inventor 4. Ergo, the explanation must be correct I've fallen victim to that line of reasoning on several occasions. -- Dave dvt at psu dot edu                                         Date: 27 Jun 2007 17:10:39 From: Michael Press Subject: Re: Safe to lengthen a chain? In article <f5tmiu$1g3e$1@f04n12.cac.psu.edu >, dvt <dvt+usenet@psu.edu > wrote: > jobst.brandt@stanfordalumni.org wrote: > > Carl Fogel writes: > > > >> You have an unfortunate habit of treating your theories as > >> unassailable facts. > > > >> No one doubts that your chain came apart, or that you found the two > >> halves. > > > >> What caused it to come apart is obviously theoretical. > > > > This is not obviously theoretical and I outlined the sequence of > > events that preclude any of the specious scenarios that have emerged > > since I posted the incident. Unless you can explain another logical > > cause for what occurred,... > > Is there a name for this logical fallacy? I'll try to outline it... > > 1. Event occurs > 2. Plausible explanation invented > 3. No other plausible explanation occurs to the inventor > 4. Ergo, the explanation must be correct > > I've fallen victim to that line of reasoning on several occasions. Perhaps False dilemma Ignoratio elenchi Anecdotal evidence Cum hoc ergo propter hoc -- Michael Press                                           Date: 28 Jun 2007 09:24:58 From: dvt Subject: Re: Safe to lengthen a chain? Michael Press wrote: > In article <f5tmiu$1g3e$1@f04n12.cac.psu.edu>, dvt > <dvt+usenet@psu.edu> wrote: >> Is there a name for this logical fallacy? I'll try to outline it... >> >> 1. Event occurs >> 2. Plausible explanation invented >> 3. No other plausible explanation occurs to the inventor >> 4. Ergo, the explanation must be correct >> >> I've fallen victim to that line of reasoning on several occasions. > Perhaps > > False dilemma > Ignoratio elenchi > Anecdotal evidence > Cum hoc ergo propter hoc Thanks, Michael and Carl. Although all of these fallacies are close, I don't think any are quite right. Carl's "argument from ignorance" is very close to the mark. Here's a definition from the web: > Arguments from ignorance infer that a proposition is true from the > fact that it is not known to be false. Source: <http://www.logicalfallacies.info/argumentfromignorance.html > You guys prompted me to find this one, too: > Questionable Cause > > This fallacy has the following general form: > > 1. A and B are associated on a regular basis. > 2. Therefore A is the cause of B. Source: <http://www.nizkor.org/features/fallacies/questionable-cause.html > That's pretty close to the fallacy I outlined, except that A and B were associated only once in Jobst's chain. So I think the fallacy I outlined is a combination of argument from ignorance and questionable cause. -- Dave dvt at psu dot edu                                             Date: 28 Jun 2007 14:02:39 From: Subject: Re: Safe to lengthen a chain? On Thu, 28 Jun 2007 09:24:58 -0400, dvt <dvt+usenet@psu.edu > wrote: >Michael Press wrote: >> In article <f5tmiu$1g3e$1@f04n12.cac.psu.edu>, dvt >> <dvt+usenet@psu.edu> wrote: > >>> Is there a name for this logical fallacy? I'll try to outline it... >>> >>> 1. Event occurs > >> 2. Plausible explanation invented >>> 3. No other plausible explanation occurs to the inventor > >> 4. Ergo, the explanation must be correct >>> >>> I've fallen victim to that line of reasoning on several occasions. > >> Perhaps >> >> False dilemma > > Ignoratio elenchi > > Anecdotal evidence > > Cum hoc ergo propter hoc > >Thanks, Michael and Carl. Although all of these fallacies are close, I >don't think any are quite right. Carl's "argument from ignorance" is >very close to the mark. Here's a definition from the web: > >> Arguments from ignorance infer that a proposition is true from the >> fact that it is not known to be false. >Source: <http://www.logicalfallacies.info/argumentfromignorance.html> > >You guys prompted me to find this one, too: > >> Questionable Cause >> >> This fallacy has the following general form: >> >> 1. A and B are associated on a regular basis. > > 2. Therefore A is the cause of B. >Source: <http://www.nizkor.org/features/fallacies/questionable-cause.html> > >That's pretty close to the fallacy I outlined, except that A and B were >associated only once in Jobst's chain. So I think the fallacy I outlined >is a combination of argument from ignorance and questionable cause. Dear Dave, To be fair, we should remember that reality is not determined by whether we use valid logic or logical fallacies. Ultimately, the question is whether chain skip can--under just the right circumstances--cause quick-connect links to come apart. If that does indeed happen, then Jobst is right, no matter how he reached his conclusion--by accident, by intuition, or by a sensible analysis of a single incident that was later buttressed by a logical fallacy or two. Cheers, Carl Fogel                                         Date: 27 Jun 2007 18:05:44 From: Subject: Re: Safe to lengthen a chain? On Wed, 27 Jun 2007 08:52:46 -0400, dvt <dvt+usenet@psu.edu > wrote: >jobst.brandt@stanfordalumni.org wrote: >> Carl Fogel writes: >> >>> You have an unfortunate habit of treating your theories as >>> unassailable facts. >> >>> No one doubts that your chain came apart, or that you found the two >>> halves. >> >>> What caused it to come apart is obviously theoretical. >> >> This is not obviously theoretical and I outlined the sequence of >> events that preclude any of the specious scenarios that have emerged >> since I posted the incident. Unless you can explain another logical >> cause for what occurred,... > >Is there a name for this logical fallacy? I'll try to outline it... > >1. Event occurs >2. Plausible explanation invented >3. No other plausible explanation occurs to the inventor >4. Ergo, the explanation must be correct > >I've fallen victim to that line of reasoning on several occasions. Dear Dave, Thanks for saving me the trouble--you put things nicely. Jobst combine two logical fallacies. First, he reverses the burden of proof. A lack of other theories in no way proves that his theory is true. Second, he argues from ignorance--his theory must be right because he is ignorant of any other theory. Jobst often argues that he must be right because he cannot imagine any other explanation--which is particularly amusing, since Jobst cannot even imagine that he could be wrong. Cheers, Carl Fogel                                         Date: 27 Jun 2007 09:39:18 From: Bill Sornson Subject: Re: Safe to lengthen a chain? "dvt" <dvt+usenet@psu.edu > wrote in message news:f5tmiu$1g3e$1@f04n12.cac.psu.edu... > jobst.brandt@stanfordalumni.org wrote: >> Carl Fogel writes: >> >>> You have an unfortunate habit of treating your theories as >>> unassailable facts. >> >>> No one doubts that your chain came apart, or that you found the two >>> halves. >> >>> What caused it to come apart is obviously theoretical. >> >> This is not obviously theoretical and I outlined the sequence of >> events that preclude any of the specious scenarios that have emerged >> since I posted the incident. Unless you can explain another logical >> cause for what occurred,... > > Is there a name for this logical fallacy? I'll try to outline it... > > 1. Event occurs > 2. Plausible explanation invented > 3. No other plausible explanation occurs to the inventor > 4. Ergo, the explanation must be correct > > I've fallen victim to that line of reasoning on several occasions. My theory? Jobst didn't install the QL correctly and it came apart. Sacrilegious Sorni                                       Date: 26 Jun 2007 21:15:50 From: Subject: Re: Safe to lengthen a chain? On 27 Jun 2007 03:01:38 GMT, jobst.brandt@stanfordalumni.org wrote: >Carl Fogel writes: > >> You have an unfortunate habit of treating your theories as >> unassailable facts. > >> No one doubts that your chain came apart, or that you found the two >> halves. > >> What caused it to come apart is obviously theoretical. > >This is not obviously theoretical [snip] Dear Jobst, Yes, it is. Treat it as a theory and people will test it against their experience, the experience of others, and other possible explanations. Treat it as unassailable fact established beyond any doubt, and you're just looking for the usual squabbling. Since you do this so often, it would seem that you're trolling by insisting that your explanations for single events cannot be questioned. Here's an example of your theory about chains conflicting with reality: http://groups.google.com/group/rec.bicycles.tech/msg/a14af7c4e0dc2fb0 You were just as certain then as you are now. Cheers, Carl Fogel                                         Date: 27 Jun 2007 03:46:17 From: Subject: Re: Safe to lengthen a chain? Carl Fogel writes: > You have an unfortunate habit of treating your theories as > unassailable facts. > No one doubts that your chain came apart, or that you found the two > halves. > What caused it to come apart is obviously theoretical. This is not obviously theoretical and I outlined the sequence of events that preclude any of the specious scenarios that have emerged since I posted the incident. Unless you can explain another logical cause for what occurred, I think it is your theoretical position that what was obvious to me under the circumstances cannot be because no one else has had the experience. That does not sit on solid ground. > Yes, it is. > Treat it as a theory and people will test it against their > experience, the experience of others, and other possible > explanations. > Treat it as unassailable fact established beyond any doubt, and > you're just looking for the usual squabbling. > Since you do this so often, it would seem that you're trolling by > insisting that your explanations for single events cannot be > questioned. I was experiencing chain skips that I recognized as a worn 13t sprocket after riding a significant distance in various gears. I had switched to my 13t sprocket once more and got a skip on the first uphill section several miles later after pedaling smoothly over a few rollers. It was not coincident with shifting, the chain had been in that gear for several rises and I use indexed shifting that stays in gear reliably. I was moving at a moderate speed of around 15mph. After the chain skipped it rolled off the chainwheel to the road as my foot got near the bottom of the stroke. I went back to the place where I estimated the chain skip occurred and found both halves of the PowerLink on the road about a foot apart, in and essentially new condition. The chain and the link were new that morning about ten miles earlier. I reassembled the chain that had no trauma and it remained that way for more than 200 miles longer. That the chain did not separate on the slack run can be deduced by how soon the chain came off. Had it been on the slack run before the derailleur, I would have gotten beyond the down-stroke before the chain rolled off onto the road. From that information, it would take some gratuitous suppositions to arrive at a different cause, but I haven't heard any that are not ruled out by the circumstances I outlined. > Here's an example of your theory about chains conflicting with > reality: http://groups.google.com/group/rec.bicycles.tech/msg/a14af7c4e0dc2fb0 > You were just as certain then as you are now. I am still as certain, however, your chain was so badly worn the you could probably do other odd bends with that chain if you could lie in a circle bent sideways as a closed loop. None of the discarded chains I have even begin to allow such curvature because I toss them out at 1% elongation (1/8 per foot). In a circle they tilt to possibly 10 degrees before resisting further twist. So you had an excessively worn chain, unlike those found on bicycles we prefer to ride. I think that's where the discussion was headed, not ho badly worn a chain can get. I think we all have enough old chains around to see that it is not possible unless the chain is worn far beyond usefulness and that it is impossible to invert when on the bicycle as was suggested even with a worn chain. Now you;ll make a chin that is that bad and show that is wrong as well. The chain bending is not in any way parallel to the current discussion, and my response at that time is as correct as it is now. Closed bicycle chains cannot be inverted (with the exception of a more than 2-3% elongation and lateral slop). Before trying this, just lay a discarded chain on a newspaper and see if it can be laid even close to circular bent sideways. So back to what you believe caused my chain separation... I haven't seen a plausible explanation. Jobst Brandt                                 Date: 26 Jun 2007 18:29:44 From: dvt Subject: Re: Safe to lengthen a chain? carlfogel@comcast.net wrote: > If I'm mistaken and this is a common problem, I'm sure that other > posters will chime in with tales of quick-connect links flying apart > when chains skip. I had a quick-connect chain come loose at least once. In the instance I remember clearly, I was sprinting out of the saddle and I shifted. Off came the chain. I was about a km from home, so the fact that I could only find half of the quick-connect link wasn't a major problem. Attributing my failure to the inertia of the chain during a skip is more of a reach than I'm willing to make. -- Dave dvt at psu dot edu                                   Date: 26 Jun 2007 20:10:31 From: Subject: Re: Safe to lengthen a chain? On Tue, 26 Jun 2007 18:29:44 -0400, dvt <dvt+usenet@psu.edu > wrote: >carlfogel@comcast.net wrote: >> If I'm mistaken and this is a common problem, I'm sure that other >> posters will chime in with tales of quick-connect links flying apart >> when chains skip. > >I had a quick-connect chain come loose at least once. In the instance I >remember clearly, I was sprinting out of the saddle and I shifted. Off >came the chain. I was about a km from home, so the fact that I could >only find half of the quick-connect link wasn't a major problem. > >Attributing my failure to the inertia of the chain during a skip is more >of a reach than I'm willing to make. Dear Dave, Inertia or not, it's a possible example of a quick connect failing. Do you remember if your chain skipping? That seems to be the crucial part of the theory. I'm skeptical of the theory, too, but willing to be convinced. It would be nice if both halves had survived, since the missing one might fractured in some curious fashion, but we can't really expect you to scour the area with a metal detector for a long-ago half-link. Cheers, Carl Fogel                                     Date: 27 Jun 2007 08:48:39 From: dvt Subject: Re: Safe to lengthen a chain? carlfogel@comcast.net wrote: > On Tue, 26 Jun 2007 18:29:44 -0400, dvt <dvt+usenet@psu.edu> wrote: > >> carlfogel@comcast.net wrote: >>> If I'm mistaken and this is a common problem, I'm sure that other >>> posters will chime in with tales of quick-connect links flying apart >>> when chains skip. >> I had a quick-connect chain come loose at least once. In the instance I >> remember clearly, I was sprinting out of the saddle and I shifted. Off >> came the chain. I was about a km from home, so the fact that I could >> only find half of the quick-connect link wasn't a major problem. >> >> Attributing my failure to the inertia of the chain during a skip is more >> of a reach than I'm willing to make. > > Dear Dave, > > Inertia or not, it's a possible example of a quick connect failing. > > Do you remember if your chain skipping? That seems to be the crucial > part of the theory. No, I don't recall any skipping prior to the event. > It would be nice if both halves had survived, since the missing one > might fractured in some curious fashion, but we can't really expect > you to scour the area with a metal detector for a long-ago half-link. Hehe. Funny idea. That half-link was lost more than a year ago... It was probably pushed into the adjoining creek by the snow plows, or some other curious fate long ago. -- Dave dvt at psu dot edu Everyone confesses that exertion which brings out all the powers of body and mind is the best thing for us; but most people do all they can to get rid of it, and as a general rule nobody does much more than circumstances drive them to do. -Harriet Beecher Stowe, abolitionist and novelist (1811-1896)                               Date: 26 Jun 2007 13:41:22 From: Tom Nakashima Subject: Re: Safe to lengthen a chain? <jobst.brandt@stanfordalumni.org > wrote in message news:46816fed$0$14107$742ec2ed@news.sonic.net... > Carl Fogel writes: > >>>>>>>>> I haven't had a chain separate in use except the time I used >>>>>>>>> a PowerLink. > >>>>>>>> I'm curious, how did your chain separate when you used a >>>>>>>> PowerLink? > >>>>>>> That event has been retold here a few times. > >>>>>>> After installing a new chain on used sprockets, the chain >>>>>>> skipped occasionally on the 13t sprocket. One of these skips >>>>>>> occurred at the precise moment before the PowerLink went into >>>>>>> engagement and the inertia of following links compressed the >>>>>>> chain enough to separate the link (after I had ridden more than >>>>>>> 10 miles). > >>>>>> I haven't heard this before, and can't imagine the PowerLink >>>>>> disengaging under tension even when rolling over such a small >>>>>> diameter as a 13t sprocket. Cyclist have used the PowerLink >>>>>> connector on 12t or even 11t sprockets without failure. The only >>>>>> way I could possibly see the PowerLink disengaging, would be >>>>>> backpedaling and having the chain getting hung-up to compress >>>>>> the PowerLink enough to become disengaged. > >>>>> Slow down. Re-read the description of PowerLink separation. It >>>>> did not separate while that part of the chain was in tension! > >>>> Given gravity, when is any part of a bicycle chain not in at least >>>> some tension? > >>> INERTIA! Read the item! As the chain was going into engagement >>> precisely at the moment the PowerLink approached the 13t sprocket, >>> the chain skipped. Chain skip accelerates the chain to move >>> forward in a few milliseconds and stops as the chain falls back >>> into engagement. Inertia of the following chain compressed the >>> PowerLink enough to make it fall apart. > >> I'm still puzzled. > >> Are you saying that a metal chain constantly slows down as it is >> _pulled_ onto a gear? > > Are you reading what I write??? > > I said I installed a new chain on used sprockets and found that the > chain skipped on the 13t sprocket as I rode to work. One of those > skips occurred just as the PowerLink approached engagement with that > 13t sprocket. Chain skip rapidly accelerates the chain (in a couple > of milliseconds) for the duration of a single link (1/2" to be exact), > after which it slows to normal chain speed. That deceleration caused > the following chain, by its inertia, to compress the PowerLink and > disengage it. > > With each iteration I'm adding words that seem to make no difference > to you and Tom. What is missing? > > ... or maybe you are pulling my leg, so to speak. > > Jobst Brandt No, don't take me wrong, it's just that I use PowerLinks. I was skeptical when they first came out, but I am a believer now from riding with them for the last three years. I have never had one fail on me yet, and have never witnessed one that has failed. I do take your words in cycling very serious, so when you say is possible that the PowerLink could fail, I'm listening and testing the theory. -tom         Date: 26 Jun 2007 09:11:51 From: Tom Nakashima Subject: Re: Safe to lengthen a chain? "Jay Beattie" <jbeattie@lindsayhart.com > wrote in message news:1182872316.757102.191630@z28g2000prd.googlegroups.com... > Am I missing something? What is all the hand-wringing about using a > chain tool on a SRAM 8 or 9sp chain? I almost always use chain tools > on my 8 and 9sp chains (Park shop tool). The only chains I have > broken in the last 20 years were at a "power link." I think these > links can bend or disengage when shifted under load under certain > circumstances (that I have not figured out yet). I still use power > links occaisionally, but for the most part, I just use a chain tool. > Also, on a really dirty chain (generally speaking, all my chains), I > can remove the chain with a tool before I can even locate the power > link -- let alone wrestle it into submission. Now, lengthening an old > chain with new links may or may not work depending on the pin wear on > the chain. Give it a whirl, see if it works, and if it doesn't, get a > new chain. -- Jay Beattie. > So what do you mean by wrestle it into submission? -tom     Date: 23 Jun 2007 20:30:12 From: Subject: Re: Safe to lengthen a chain? Chris Nelson writes: > PowerLinks take much power to disengage on a used (dirty) chain. I > found that using pliers diagonally, end-to-end of the link, > compresses it in both directions enough to open it. That is, if you > need to open the chain in the field, as one does if a stick damages > the derailleur, a CPR-9 chain tool is the way to do it. You > probably cannot get a PowerLink open without tools. > You can, but it takes a multitude of four letter words strung > together with rage. The Connex power however, is easy to operate by > fingers. The Connex link is no different from the PowerLink in that it must be compressed laterally to disengage. What makes you think that a chain in similar condition to the one that doesn't freely release a PowerLink will do so for a Connex? Jobst Brandt   Date: 23 Jun 2007 09:13:03 From: Johnny Sunset Subject: Re: Safe to lengthen a chain? On Jun 23, 9:45 am, still me who? wrote: > On Sat, 23 Jun 2007 06:19:03 -0700, Kenny who? wrote: > > >On Jun 23, 1:51 am, "bw2" wrote: > >> I cut a new PC59 chain one link too short. Is it safe to add that > >> link back on? > > >> Thanks. > > >To be absolutely safe use a snap link or powerlink. > > Retro oriented question: Why is this true with "modern" chains? Do > they peen the heads larger ? > > If using SRAM chains, at what point in the line does this become an > issue - pc48? 58? I have thousands of miles on 7/8 speed Shimano HG chains that had the pin pushed out just enough to break the chain, then reattached with no problem. However, I was not able to even get a 9-speed Shimano chain back together as an emergency repair (for someone else). -- Tom Sherman - Holstein-Friesland Bovinia The weather is here, wish you were beautiful     Date: 26 Jun 2007 11:53:26 From: Jay Beattie Subject: Re: Safe to lengthen a chain? On Jun 26, 11:19 am, jobst.bra...@stanfordalumni.org wrote: > Jay Beattie writes: > > First off, if you break a link, you can not fix it with a PowerLink > > or Connex alone. You will need a chain tool to take out the other > > end of the bent link plate/pin so you have two female ends you can > > connect. Second, I have broken a number of chains (good, stout > > 5/6sp) while riding out of the saddle and never went OTB. It's like > > missing a shift while climbing and dropping the chain. YMMV, but I > > never saw it as a life changing or super-dangerous event. > > BTW, I have broken cranks and pedals while riding out of the saddle > > and have never gone OTB. In fact, I was more concerned with > > slamming my balls on the top tube or wobbling in to traffic (neither > > of which happened). Broken bars or forks are a different story. > > The failures you had must have been at a low speed because with one > foot in the pedal and the other on the road at anything above 10mph is > a certain fall to the side of the pedal/crank failure. Running fast > enough with one foot to keep the bicycle from falling is impossible > with the other foot fixed astride a bicycle. The out-of-the-saddle failures were at low speeds on fairly steep climbs except one -- which was on a slight climb at maybe 18mph with my weight relatively centered (humping up that slight hill on HWY 30 up to Savie Island, for you locals). That was a NR crank failure, and my right foot hit the ground with the pedal attached. I stayed basically upright although leaned over to the right skidding on my foot. Have you ever gone over the bars with a transmission failure? I do not want to give people the impression that there is no danger involved with a broken chain, crank, pedal, etc., but I do not see it as a danger of going over the bars. I worry more about wobbling in to traffic or falling to the side. -- Jay Beattie.       Date: 26 Jun 2007 21:32:23 From: Andrew Lee Subject: Re: Safe to lengthen a chain? Jay Beattie wrote: > Have you ever gone over the bars with a transmission failure? I do not > want to give people the impression that there is no danger involved > with a broken chain, crank, pedal, etc., but I do not see it as a > danger of going over the bars. I worry more about wobbling in to > traffic or falling to the side. -- Jay Beattie. Either way you can get seriously injured or worse, so it's best not to have transmission failure. I think I went over the bars when the chain skipped (more like leaped and completely disengaged) on my first road bike (ancient at the time) back in high school. The chain and rear sprockets were massively worn and the chain would sometimes just let loose and slide over the sprockets. I knew this and generally tried to be careful when out of the saddle, but I sometimes forgot. I had just rolled off the school grounds on the way home and stood to accelerate hard (I liked to race cars down the street going to and from school back then) and BLAM... I was suddenly on the ground with a twisted frame, bent fork, and tacoed front wheel. I'm pretty sure I went over the bars and did a roll out onto the ground, but I was on the ground before I knew it. I didn't go off to the side into traffic, and I wasn't hurt (excluding minor scrapes which I wouldn't remember).       Date: 26 Jun 2007 17:01:03 From: A Muzi Subject: Re: Safe to lengthen a chain? Jay Beattie wrote: > On Jun 26, 11:19 am, jobst.bra...@stanfordalumni.org wrote: >> Jay Beattie writes: >>> First off, if you break a link, you can not fix it with a PowerLink >>> or Connex alone. You will need a chain tool to take out the other >>> end of the bent link plate/pin so you have two female ends you can >>> connect. Second, I have broken a number of chains (good, stout >>> 5/6sp) while riding out of the saddle and never went OTB. It's like >>> missing a shift while climbing and dropping the chain. YMMV, but I >>> never saw it as a life changing or super-dangerous event. >>> BTW, I have broken cranks and pedals while riding out of the saddle >>> and have never gone OTB. In fact, I was more concerned with >>> slamming my balls on the top tube or wobbling in to traffic (neither >>> of which happened). Broken bars or forks are a different story. >> The failures you had must have been at a low speed because with one >> foot in the pedal and the other on the road at anything above 10mph is >> a certain fall to the side of the pedal/crank failure. Running fast >> enough with one foot to keep the bicycle from falling is impossible >> with the other foot fixed astride a bicycle. > > The out-of-the-saddle failures were at low speeds on fairly steep > climbs except one -- which was on a slight climb at maybe 18mph with > my weight relatively centered (humping up that slight hill on HWY 30 > up to Savie Island, for you locals). That was a NR crank failure, and > my right foot hit the ground with the pedal attached. I stayed > basically upright although leaned over to the right skidding on my > foot. > > Have you ever gone over the bars with a transmission failure? I do not > want to give people the impression that there is no danger involved > with a broken chain, crank, pedal, etc., but I do not see it as a > danger of going over the bars. I worry more about wobbling in to > traffic or falling to the side. -- Jay Beattie. Agreed. I don't recall any reports of 'over the bars'. Falling into traffic is bad enough. Modern (8-9-10) chain rivets seem to be more prone to user error from what we see here. It is not impossible but, unlike, say, a 1/8 inch roller chain, there's little margin for error. Pins are tighter, plates are thinner, rivets are flush or nearly so. -- Andrew Muzi www.yellowjersey.org Open every day since 1 April, 1971       Date: 26 Jun 2007 19:04:46 From: Subject: Re: Safe to lengthen a chain? Jay Beattie writes: >>> First off, if you break a link, you can not fix it with a >>> PowerLink or Connex alone. You will need a chain tool to take out >>> the other end of the bent link plate/pin so you have two female >>> ends you can connect. Second, I have broken a number of chains >>> (good, stout 5/6sp) while riding out of the saddle and never went >>> OTB. It's like missing a shift while climbing and dropping the >>> chain. YMMV, but I never saw it as a life changing or >>> super-dangerous event. BTW, I have broken cranks and pedals while >>> riding out of the saddle and have never gone OTB. In fact, I was >>> more concerned with slamming my balls on the top tube or wobbling >>> in to traffic (neither of which happened). Broken bars or forks >>> are a different story. >> The failures you had must have been at a low speed because with one >> foot in the pedal and the other on the road at anything above 10mph >> is a certain fall to the side of the pedal/crank failure. Running >> fast enough with one foot to keep the bicycle from falling is >> impossible with the other foot fixed astride a bicycle. > The out-of-the-saddle failures were at low speeds on fairly steep > climbs except one -- which was on a slight climb at maybe 18mph with > my weight relatively centered (humping up that slight hill on HWY 30 > up to Savie Island, for you locals). That was a NR crank failure, > and my right foot hit the ground with the pedal attached. I stayed > basically upright although leaned over to the right skidding on my > foot. > Have you ever gone over the bars with a transmission failure? I do > not want to give people the impression that there is no danger > involved with a broken chain, crank, pedal, etc., but I do not see > it as a danger of going over the bars. I worry more about wobbling > in to traffic or falling to the side. As I said, I had two SA 3-speed hub disengagements that both caused endo's, both occurring in top gear standing. After the second one, I analyzed the problem and noted that an SA hub must disengage with any continuous torque and chain pull to flex the axle. The driver-cross (clutch) runs askew to the planet carrier and works its way out of engagement. If you doubt it, look at any driver cross and you will see disengagement ramps on the pressure faces. This failure has been attributed to improper shift chain adjustment for the last 70 years. THAT"S A LIE! I have proposed how to remedy that but the SA AW 3-speed is history anyway. Jobst Brandt     Date: 26 Jun 2007 10:59:38 From: Jay Beattie Subject: Re: Safe to lengthen a chain? On Jun 26, 9:40 am, Qui si parla Campagnolo <p...@vecchios.com > wrote: > On Jun 24, 4:36 am, Chris Nelson <smilin...@hotmail.com> wrote: > > > > > > > On Jun 23, 9:59 pm, still me <wheeled...@yahoo.com> wrote: > > > > On Sat, 23 Jun 2007 18:23:05 -0700, Chris Nelson > > > > <smilin...@hotmail.com> wrote: > > > >Actually the pins are completely round. The safety comes from > > > >oversized links that collide with adjacent outer links when applying > > > >removal action in a parallel alignment. > > > > >Chris > > > > Well, that argument aside... is it safe for me to lengthen or shorten > > > PC48 chains the old fashioned way with a chain pin tool ? > > > Yes, its fairly safe. The worst that could happen is the pin pops back > > out while riding and the chain falls off > > No, the worse that can happen is the chain can break when climbing and > you 'can' take your front teeth out. Not fairly safe at all..poor > advice. > > . Bring an extra connex link First off, if you break a link, you can not fix it with a power link or connex alone. You will need a chain tool to take out the other end of the bent link plate/pin so you have two female ends you can connect. Second, I have broken a number of chains (good, stout 5/6sp) while riding out of the saddle and never went OTB. It's like missing a shift while climbing and dropping the chain. YMMV, but I never saw it as a life changing or super-dangerous event. BTW, I have broken cranks and pedals while riding out of the saddle and have never gone OTB. In fact, I was more concerned with slamming my balls on the top tube or wobbling in to traffic (neither of which happened). Broken bars or forks are a different story. -- Jay Beattie.       Date: 26 Jun 2007 18:19:28 From: Subject: Re: Safe to lengthen a chain? Jay Beattie writes: > First off, if you break a link, you can not fix it with a PowerLink > or Connex alone. You will need a chain tool to take out the other > end of the bent link plate/pin so you have two female ends you can > connect. Second, I have broken a number of chains (good, stout > 5/6sp) while riding out of the saddle and never went OTB. It's like > missing a shift while climbing and dropping the chain. YMMV, but I > never saw it as a life changing or super-dangerous event. > BTW, I have broken cranks and pedals while riding out of the saddle > and have never gone OTB. In fact, I was more concerned with > slamming my balls on the top tube or wobbling in to traffic (neither > of which happened). Broken bars or forks are a different story. The failures you had must have been at a low speed because with one foot in the pedal and the other on the road at anything above 10mph is a certain fall to the side of the pedal/crank failure. Running fast enough with one foot to keep the bicycle from falling is impossible with the other foot fixed astride a bicycle. A drive train failure (chain/freewheel/3-speed hub) is similar because it occurs when pushing hard, with rider CG ahead of the forward foot, failure occurring on the downstroke. Even at low speed this causes roughly a handstand on the bars when pulling hard with the other foot. My experience is with more than two dozen crank failures and two SA 3-speed hub disengagements that produced the predictable results. Jobst Brandt     Date: 26 Jun 2007 09:40:40 From: Qui si parla Campagnolo Subject: Re: Safe to lengthen a chain? On Jun 24, 4:36 am, Chris Nelson <smilin...@hotmail.com > wrote: > On Jun 23, 9:59 pm, still me <wheeled...@yahoo.com> wrote: > > > On Sat, 23 Jun 2007 18:23:05 -0700, Chris Nelson > > > <smilin...@hotmail.com> wrote: > > >Actually the pins are completely round. The safety comes from > > >oversized links that collide with adjacent outer links when applying > > >removal action in a parallel alignment. > > > >Chris > > > Well, that argument aside... is it safe for me to lengthen or shorten > > PC48 chains the old fashioned way with a chain pin tool ? > > Yes, its fairly safe. The worst that could happen is the pin pops back > out while riding and the chain falls off No, the worse that can happen is the chain can break when climbing and you 'can' take your front teeth out. Not fairly safe at all..poor advice. . Bring an extra connex link > with you on the ride to repair. > > Chris     Date: 26 Jun 2007 09:38:41 From: Qui si parla Campagnolo Subject: Re: Safe to lengthen a chain? On Jun 23, 7:59 pm, still me <wheeled...@yahoo.com > wrote: > On Sat, 23 Jun 2007 18:23:05 -0700, Chris Nelson > > <smilin...@hotmail.com> wrote: > >Actually the pins are completely round. The safety comes from > >oversized links that collide with adjacent outer links when applying > >removal action in a parallel alignment. > > >Chris > > Well, that argument aside... is it safe for me to lengthen or shorten > PC48 chains the old fashioned way with a chain pin tool ? Shorten, sure but you cannot push a pin back into the plate to lengthen. Softish pin and when you push it back in you deform it(and the plate). Chances to have the chain fail there is BIG.     Date: 24 Jun 2007 18:57:13 From: Chris Nelson Subject: Re: Safe to lengthen a chain? On Jun 24, 8:08 pm, A Muzi <a...@yellowjersey.org > wrote: > >> <smilin...@hotmail.com> wrote: > >>> Actually the pins are completely round. The safety comes from > >>> oversized links that collide with adjacent outer links when applying > >>> removal action in a parallel alignment. > > still me <wheeled...@yahoo.com> wrote: > >> Well, that argument aside... is it safe for me to lengthen or shorten > >> PC48 chains the old fashioned way with a chain pin tool ? > Chris Nelson wrote: > > Yes, its fairly safe. The worst that could happen is the pin pops back > > out while riding and the chain falls off. Bring an extra connex link > > with you on the ride to repair. > > To some riders, "The worst that could happen is the pin pops back > out" could mean serious injury or death. Have you experienced broken a > chain while standing yourself? > > It may be interpretive, but "broken chain" and "fairly safe" are not the > same in my book. > -- > Andrew Muziwww.yellowjersey.org > Open every day since 1 April, 1971 My bad. It was a poor attempt at being facetious. If it were me, I would throw out the butchered chain, buy new and use a connex link. But others don't seem to think their life is worth $25. Yes, I've done the out-of-the-saddle broken chain thing, not pretty. The failures that I have experienced were with connector pins which I don't use anymore. Since then I've gone exclusively with removable links which I find to be much more reliable. The extra $5 is worth the price of living. YMMV. Chris     Date: 24 Jun 2007 09:02:41 From: andresmuro@aol.com Subject: Re: Safe to lengthen a chain? On Jun 23, 7:59 pm, still me <wheeled...@yahoo.com > wrote: > On Sat, 23 Jun 2007 18:23:05 -0700, Chris Nelson > > <smilin...@hotmail.com> wrote: > >Actually the pins are completely round. The safety comes from > >oversized links that collide with adjacent outer links when applying > >removal action in a parallel alignment. > > >Chris > > Well, that argument aside... is it safe for me to lengthen or shorten > PC48 chains the old fashioned way with a chain pin tool ? Up to 8 speed, sram chains can be shortened or lengthened the old fashion way. Beyond 8 speed, you need to use connectors whether to lengthen or shorten. Andres     Date: 24 Jun 2007 03:36:13 From: Chris Nelson Subject: Re: Safe to lengthen a chain? On Jun 23, 9:59 pm, still me <wheeled...@yahoo.com > wrote: > On Sat, 23 Jun 2007 18:23:05 -0700, Chris Nelson > > <smilin...@hotmail.com> wrote: > >Actually the pins are completely round. The safety comes from > >oversized links that collide with adjacent outer links when applying > >removal action in a parallel alignment. > > >Chris > > Well, that argument aside... is it safe for me to lengthen or shorten > PC48 chains the old fashioned way with a chain pin tool ? Yes, its fairly safe. The worst that could happen is the pin pops back out while riding and the chain falls off. Bring an extra connex link with you on the ride to repair. Chris       Date: 27 Jun 2007 17:59:05 From: Johnny Sunset Subject: Re: Safe to lengthen a chain? On Jun 27, 4:35 pm, Bill Bushnell aka Mr. Bill wrote: > Jobst Brandt wrote: > > I'll leave that part of the scenario to Bill Bushnell to explain. You > > assume the rider is not attached to his pedals, which Bill is and you > > assume he would limply let his foot fall under the bicycle. If you go > > that far, you can describe worse scenarios for upright bicycles that > > are bad enough already. I've tried them. > > A sudden chain break (or crank failure or most likely, clip disengagement) on a > recumbent sends the foot flying forward, usually harmlessly.... I did that several times on my RANS Rocket, until I switched from SH-55 "M" to SH-51 "S" cleats. -- Tom Sherman - Holstein-Friesland Bovinia The weather is here, wish you were beautiful       Date: 26 Jun 2007 22:00:19 From: Johnny Sunset Subject: Re: Safe to lengthen a chain? On Jun 26, 9:32 pm, Dear Carl wrote: > On 27 Jun 2007 01:07:32 GMT, Jobst Brandt wrote: > > >Bill Bushnell writes: > > >>>> Modern chain pins are beveled on each side for added strength. Once > >>>> the pin is pushed through it flattens out the bevel and weakens that > >>>> link. > > >>> I think you have that backward. 10-speed chain pins have no bevel and > >>> are flush with the side plate. When pushed in, the original pin > >>> broaches a larger hole in the side plate so it has no suitable press > >>> fit and can disengage. The damage is not apparent because the other > >>> end of the pin still has a press fit and masks the loose fit in the > >>> re-engaged side plate. > > >>> It is not that any part of the chain breaks (weakens that link) but > >>> that the side plate bends outward losing support from its pin. > > >> For many years I used cheap Hyperglide 9-speed chains (HG53, HG73) > >> and was too cheap to use special $5 pins when connecting them. > >> Early on I occasionally broke and bent links: > > >>http://tinyurl.com/2353aj > > >> This failure mode became much less frequent after I added a step to > >> smash between two hammers the ends of a re-inserted pin so that the > >> ends of the pin flared to cover the gap between the link and the > >> pin. While it wasn't as sturdy as the original press fit, I found > >> it reliable enough on a bike I never rode standing. > > >> Since the strength of the flare from pin-smashing is variable, I > >> wouldn't recommend the technique for a bike that is ridden standing > >> due to the risk of severe injury. All of my prior failures had > >> occurred while shifting when the chain was under high tension (low > >> speed, low gear), where chain failure was inconvenient but not > >> injurious. > > >> I have since switched to KMC and SRAM chains and now have a > >> collection of quick links that I'm not too stingy to use. > > >You're cheating. There is no way you can go over the bars of fall off > >your recumbent from a chain separation. We old fashioned upright > >bicycle riders cannot take that risk. > > >Jobst Brandt > > Dear Jobst, > > Unfortunately, low-profile recumbents may actually face more dangers. > > If a low-profile recumbent rider isn't using clipless pedals or if he > accidentally twists out of them when a chain breaks, the result can be > a very bad crash in which his foot plants, his knee bends back under > him like a limbo dancer doing 20 mph or more, and his leg is jammed > under his bike and body. > > The results can include a dislocated hip, mangled knee, and all sorts > of other massive damage from toe to hip. > > And that's just what happens as the rider and bike fly up into the > air. > > Landing hurts, too. If the rider's foot comes off the pedal [1] from the above causes, it will happen during the "power" portion of the stroke, which results in the rider's foot going forward, not downwards towards the ground. It is easy to recover from this without one's foot coming close to the ground, which Dear Carl would realize if he had actually "been there and done that". The real danger is not using foot retention and having one's foot come off the pedals over a bump when coasting. [1] Been there, done that due to loose SPD tension and chain derailment. -- Tom Sherman - Holstein-Friesland Bovinia       Date: 24 Jun 2007 19:08:37 From: A Muzi Subject: Re: Safe to lengthen a chain? >> <smilin...@hotmail.com> wrote: >>> Actually the pins are completely round. The safety comes from >>> oversized links that collide with adjacent outer links when applying >>> removal action in a parallel alignment. > still me <wheeled...@yahoo.com> wrote: >> Well, that argument aside... is it safe for me to lengthen or shorten >> PC48 chains the old fashioned way with a chain pin tool ? Chris Nelson wrote: > Yes, its fairly safe. The worst that could happen is the pin pops back > out while riding and the chain falls off. Bring an extra connex link > with you on the ride to repair. To some riders, "The worst that could happen is the pin pops back out" could mean serious injury or death. Have you experienced broken a chain while standing yourself? It may be interpretive, but "broken chain" and "fairly safe" are not the same in my book. -- Andrew Muzi www.yellowjersey.org Open every day since 1 April, 1971         Date: 28 Jun 2007 12:47:01 From: Chris Nelson Subject: Re: Safe to lengthen a chain? On Jun 28, 9:39 am, Peter Cole <peter_c...@comcast.net > wrote: > Chris Nelson wrote: > > On Jun 27, 9:03 am, Peter Cole <peter_c...@comcast.net> wrote: > >> Chris Nelson wrote: > >>> On Jun 26, 9:29 pm, jobst.bra...@stanfordalumni.org wrote: > >>>> Chris Nelson writes: > >>>>>>> Both sides are beveled, there is no wrong end. The bevels are bent > >>>>>>> in the direction that would allow the pin to be removed. > >>>>>> From what you write, I suspect you don't know what a bevel is. > >>>>>> There is no way to orient a bevel on the end of a pin. > >>>>>> Again: How is does pushing the pin out destroy the bevel? > >>>>>> As in : "You will see that the end that traveled through the links > >>>>>> has lost its bevel and the end that did not have to travel through > >>>>>> the links has retained its bevel." > >>>>> Push a pin out and look for yourself. Wanna borrow my Park CT-3 ? > >>>> Well, I dropped by the bicycle shop and picked up such a chain and, > >>>> yes, you have your terms mixed up. The pins are flared on both ends, > >>>> not beveled. A bevel at the end of a pin/shaft is a taper used to > >>>> prevent broaching when pressing the circular profile into a round > >>>> hole. > >>>> See:http://www.radax.com/store.asp?pid=14559 > >>>> Ten speed chains have flared ends and it is the flare that breaks off > >>>> when pushed out. This leaves a sharp jagged end that cannot be > >>>> reasonably pressed into a chain. The ends of the Shimano Dura Ace > >>>> chain is swaged after insertion by forming a dimple in each end. > >>>> Jobst Brandt > >>> Flared would be a more accurate description than beveled, my mistake. > >> Actually, the descriptions are opposite. > > >>> But my point still stands, that a pin when removed and reinserted > >>> results in a weaker link because of damage to the pin "flare". In > >>> fact, the instructions that come with Shimano chain warns against > >>> reinserting pins. > >> Which is why I stopped using Shimano chains years ago. I have not had > >> Sachs 8-speed chains fail after joining with a pin after I discovered > >> how critical it was to make sure the pin protrudes exactly the right > >> amount from the side plates. > > >> I have not had a quick link fail, but for one to come undone without > >> damage, it would seem that the only possible way would be to have the > >> link undergo compression. > > >> I pulled my daughter for years up steep off-road trails, with her weight > >> up to 90 lb and mine at 230. That, combined with very low gearing and > >> long cranks probably represented chain tensions beyond that which most > >> riders generate.- Hide quoted text - > > >> - Show quoted text - > > > SRAM also uses "flared" pins for strength. The exception being the > > special connector pin that there is only one of(if not using the > > Powerlink). > > Where did you see this? I know Shimano uses special pins, but I have > never seen these with a SRAM chain, nor in their manual. > > The removal and reinstalling of the chain by pins other > > > than the special connector pin will result in a chain whose integrity > > has been compromised. Not sure of the effects of repeated connector > > pin removal. SRAM instructions cautions the user to use the Powerlink. > > I didn't see that caution in the online manual.- Hide quoted text - > > - Show quoted text - Instructions come with the chain. SRAM calls it a clamping pin and is already inserted into one side of the end outer link in the diagram. I'm not sure if they still ship chains this way if the PowerLink is included with the chain. Chris           Date: 28 Jun 2007 16:16:47 From: Peter Cole Subject: Re: Safe to lengthen a chain? Chris Nelson wrote: > On Jun 28, 9:39 am, Peter Cole <peter_c...@comcast.net> wrote: >> Chris Nelson wrote: >>> On Jun 27, 9:03 am, Peter Cole <peter_c...@comcast.net> wrote: >>>> Chris Nelson wrote: >>>>> On Jun 26, 9:29 pm, jobst.bra...@stanfordalumni.org wrote: >>>>>> Chris Nelson writes: >>>>>>>>> Both sides are beveled, there is no wrong end. The bevels are bent >>>>>>>>> in the direction that would allow the pin to be removed. >>>>>>>> From what you write, I suspect you don't know what a bevel is. >>>>>>>> There is no way to orient a bevel on the end of a pin. >>>>>>>> Again: How is does pushing the pin out destroy the bevel? >>>>>>>> As in : "You will see that the end that traveled through the links >>>>>>>> has lost its bevel and the end that did not have to travel through >>>>>>>> the links has retained its bevel." >>>>>>> Push a pin out and look for yourself. Wanna borrow my Park CT-3 ? >>>>>> Well, I dropped by the bicycle shop and picked up such a chain and, >>>>>> yes, you have your terms mixed up. The pins are flared on both ends, >>>>>> not beveled. A bevel at the end of a pin/shaft is a taper used to >>>>>> prevent broaching when pressing the circular profile into a round >>>>>> hole. >>>>>> See:http://www.radax.com/store.asp?pid=14559 >>>>>> Ten speed chains have flared ends and it is the flare that breaks off >>>>>> when pushed out. This leaves a sharp jagged end that cannot be >>>>>> reasonably pressed into a chain. The ends of the Shimano Dura Ace >>>>>> chain is swaged after insertion by forming a dimple in each end. >>>>>> Jobst Brandt >>>>> Flared would be a more accurate description than beveled, my mistake. >>>> Actually, the descriptions are opposite. >>>>> But my point still stands, that a pin when removed and reinserted >>>>> results in a weaker link because of damage to the pin "flare". In >>>>> fact, the instructions that come with Shimano chain warns against >>>>> reinserting pins. >>>> Which is why I stopped using Shimano chains years ago. I have not had >>>> Sachs 8-speed chains fail after joining with a pin after I discovered >>>> how critical it was to make sure the pin protrudes exactly the right >>>> amount from the side plates. >>>> I have not had a quick link fail, but for one to come undone without >>>> damage, it would seem that the only possible way would be to have the >>>> link undergo compression. >>>> I pulled my daughter for years up steep off-road trails, with her weight >>>> up to 90 lb and mine at 230. That, combined with very low gearing and >>>> long cranks probably represented chain tensions beyond that which most >>>> riders generate.- Hide quoted text - >>>> - Show quoted text - >>> SRAM also uses "flared" pins for strength. The exception being the >>> special connector pin that there is only one of(if not using the >>> Powerlink). >> Where did you see this? I know Shimano uses special pins, but I have >> never seen these with a SRAM chain, nor in their manual. >> >> The removal and reinstalling of the chain by pins other >> >>> than the special connector pin will result in a chain whose integrity >>> has been compromised. Not sure of the effects of repeated connector >>> pin removal. SRAM instructions cautions the user to use the Powerlink. >> I didn't see that caution in the online manual.- Hide quoted text - >> >> - Show quoted text - > > Instructions come with the chain. SRAM calls it a clamping pin and is > already inserted into one side of the end outer link in the diagram. > I'm not sure if they still ship chains this way if the PowerLink is > included with the chain. > > Chris > From the SRAM instructions: "2.2 Closing chain (standard version with clamping pin) • Fit chain, bring the two ends together and press pin (Fig. 2) through with assembly tool. The pin must extend by the same amount at both outer plates. It must be possible to move the connecting link slightly. • The use of the SRAM assembly plier (Part No. 00 2799 980 001) is recommended for PC 68, PC 58 and PC 48. (Fig.3)" You *could* read this as implying that the "clamping pin" is special somehow, or it could just mean that it's the pin that you close the chain with. I don't remember if there was anything special about the SRAM/Sachs "open" pins in the pre quick link days, or even if they came with an "open" pin. If they did have a special "clamping pin" which they left open, I don't know how you'd find it again, or if you did, whether it would be a good idea to reuse it every time you removed your chain. I certainly don't remember them having a Shimano approach of "one time" "clamping pins". FWIW, they don't, as you claim, caution you to use the quick link, only to use a new one with a new chain.         Date: 26 Jun 2007 14:43:53 From: still me Subject: Re: Safe to lengthen a chain? On Sun, 24 Jun 2007 19:08:37 -0500, A Muzi <am@yellowjersey.org > wrote: >To some riders, "The worst that could happen is the pin pops back >out" could mean serious injury or death. Have you experienced broken a >chain while standing yourself? > >It may be interpretive, but "broken chain" and "fairly safe" are not the >same in my book. That would be my concern. I'm good with the chain tool... but I don't want a chain break. On the flip side, I do sometimes need to change chain length when I change gearing and I don't like the idea of multiple power links in a chain... or the requirement to have a half dozen "short bits" to make up the lengths I might need. So, the 'ol chain tool idea is quite convenient. Still, I guess I'm a little confused - even if the new chain starts out tighter, if it ends up as tight as the 'ol chains, wouldn't the connection be just as strong as the one we had in the old days? In other words, it's not as tight as a new 8sp chain, but it's as tight as the older 5/6 sp chain that was perfectly reliable and never failed ?           Date: 26 Jun 2007 18:27:38 From: Joe Riel Subject: Re: Safe to lengthen a chain? jobst.brandt@stanfordalumni.org writes: > Tom Nakashima writes: > >>>>> I'm still puzzled. > >>>>> Are you saying that a metal chain constantly slows down as it is >>>>> _pulled_ onto a gear? > >>>> OK, I reread it. Shifting from a bigger sprocket onto the >>>> 13t...(friction shifters I take it?) It's possible, but I'm still >>>> not convinced here, because I don't think a millisecond is enough >>>> time for the PowerLink to disengage. > >>> STOP!!!! > >>> Please explain what you don't understand about riding in one gear >>> and having the chain skip. What in hell does friction shifting >>> have to do with chain skip? This is getting ridiculous. New >>> chains skip on worn sprockets. I have indexed shifting. > >> OK, thought you were using friction shifters, in shifting down to >> the 13t but not having it engaged all the way. That's what I >> thought when you said skipping? > > Did you see anything about shifting gears in what I wrote? Did I say > anything about gear engagement? Did I say I had ridden more than 10 > miles before the incident that occurred when I stood up in the gear > and the chain skipped? Did I not explain that it is the inertia of > the following chain that compressed the link? Stop and think about > this a moment. I'm not new to bicycling so don't create any scenarios > that might have missed my observation in this chain problem. I don't know about Tom, but a lot of riders replace their equipment so frequently that I wouldn't be surprised if there is a sizeable population of riders that have never experienced chain skip and so wouldn't know what you meant by it. -- Joe Riel             Date: 27 Jun 2007 12:08:03 From: John Henderson Subject: Re: Safe to lengthen a chain? Joe Riel wrote: > I don't know about Tom, but a lot of riders replace their > equipment so frequently that I wouldn't be surprised if there > is a sizeable population of riders that have never experienced > chain skip and so wouldn't know what you meant by it. Or get their bike professionally serviced, and get sold a cassette when the chain is changed. I've seen a chain separate when a Connex link disintegrated - one side plate just broke up, and the other dropped out - I found the pieces. I'm puzzled by how it happened - perhaps it wasn't properly engaged on assembly. John       Date: 24 Jun 2007 13:02:32 From: still me Subject: Re: Safe to lengthen a chain? On Sun, 24 Jun 2007 03:36:13 -0700, Chris Nelson <smilin321@hotmail.com > wrote: > >Yes, its fairly safe. The worst that could happen is the pin pops back >out while riding and the chain falls off. Well, I would think that would not be safe if it happened at the wrong moment :-) > Bring an extra connex link >with you on the ride to repair.     Date: 23 Jun 2007 19:36:09 From: Subject: Re: Safe to lengthen a chain? Tom Sherman writes: >>>> I cut a new PC59 chain one link too short. Is it safe to add >>>> that link back on? >>> To be absolutely safe use a snap link or PowerLink. >> Retro oriented question: Why is this true with "modern" chains? Do >> they peen the heads larger? >> If using SRAM chains, at what point in the line does this become an >> issue - pc48? 58? > I have thousands of miles on 7/8 speed Shimano HG chains that had > the pin pushed out just enough to break the chain, then reattached > with no problem. However, I was not able to even get a 9-speed > Shimano chain back together as an emergency repair (for someone > else). As I mentioned here once, I used a PowerLink when installing a new pc48 chain and only noticed that the chain would skip on the 13t if I pushed hard. That was an exciting experiment because the chain skipped exactly when the PowerLink was one pitch from engaging the skipping sprocket. Being clean and new, it compressed from chain inertia and disengaged allowing the chain to fall off as well. I went back to the spot, picked up the two halves of the link lying in the road, and reinstalled the chain, to finish my ride to work. This never occurred again but then it couldn't. Once a chain is dirty, it has grit between the plates leaving insufficient space to compress laterally and disengage. I discovered this when I tried to take the chain off in the field, which made me decided to skip the entire concept, the pc48 working just fine with a re-inserted pin as Tom described. PowerLinks take much power to disengage on a used (dirty) chain. I found that using pliers diagonally, end-to-end of the link, compresses it in both directions enough to open it. That is, if you need to open the chain in the field, as one does if a stick damages the derailleur, a CPR-9 chain tool is the way to do it. You probably cannot get a PowerLink open without tools. Jobst Brandt       Date: 24 Jun 2007 15:10:12 From: Booker C. Bense Subject: Re: Safe to lengthen a chain? In article <467d7629$0$14133$742ec2ed@news.sonic.net >, <jobst.brandt@stanfordalumni.org > wrote: > >PowerLinks take much power to disengage on a used (dirty) chain. I >found that using pliers diagonally, end-to-end of the link, compresses >it in both directions enough to open it. That is, if you need to open >the chain in the field, as one does if a stick damages the derailleur, >a CPR-9 chain tool is the way to do it. You probably cannot get a >PowerLink open without tools. > This is simply not true in my experience, there is a trick to it but once mastered SRAM powerlinks actually get easier to open with use. I have them on all my bikes and can easily break the chain with just my hands, no tools required. I wish could explain the trick fully, but I can't. The basics are to make a Z with the link and apply shear, but not compressive force. If you squeeze the link, it won't slide. I did have a lot of trouble with these at the start, but since I mastered the trick I haven't had to resort to tools to break the power link over the last 4 years. _ Booker C. Bense         Date: 25 Jun 2007 08:51:21 From: Michael Warner Subject: Re: Safe to lengthen a chain? On Sun, 24 Jun 2007 15:10:12 +0000 (UTC), Booker C. Bense wrote: >>PowerLinks take much power to disengage on a used (dirty) chain. I >>found that using pliers diagonally, end-to-end of the link, compresses >>it in both directions enough to open it. That is, if you need to open >>the chain in the field, as one does if a stick damages the derailleur, >>a CPR-9 chain tool is the way to do it. You probably cannot get a >>PowerLink open without tools. > This is simply not true in my experience, there is a trick to it > but once mastered SRAM powerlinks actually get easier to open > with use. I have them on all my bikes and can easily break the > chain with just my hands, no tools required. > > I wish could explain the trick fully, but I can't. The basics are to > make a Z with the link and apply shear, but not compressive > force. If you squeeze the link, it won't slide. I've never had trouble with the 9-speed links - on a dirty chain, my main problem is finding it! I just squeeze the plates together, then hold the link either side and push them inward. But the 8-speed version seems much tighter when new. I've had to do a lot of pushing, wiggling and swearing to get them on and off sometimes. -- Home page: http://members.westnet.com.au/mvw           Date: 25 Jun 2007 17:34:47 From: Booker C. Bense Subject: Re: Safe to lengthen a chain? In article <1jlkm3t872758.8d1y935yz2fx$.dlg@40tude.net >, Michael Warner <mvw@westnet.com.au > wrote: >On Sun, 24 Jun 2007 15:10:12 +0000 (UTC), Booker C. Bense wrote: > >>>PowerLinks take much power to disengage on a used (dirty) chain. I >>>found that using pliers diagonally, end-to-end of the link, compresses >>>it in both directions enough to open it. That is, if you need to open >>>the chain in the field, as one does if a stick damages the derailleur, >>>a CPR-9 chain tool is the way to do it. You probably cannot get a >>>PowerLink open without tools. > >> This is simply not true in my experience, there is a trick to it >> but once mastered SRAM powerlinks actually get easier to open >> with use. I have them on all my bikes and can easily break the >> chain with just my hands, no tools required. >> >> I wish could explain the trick fully, but I can't. The basics are to >> make a Z with the link and apply shear, but not compressive >> force. If you squeeze the link, it won't slide. > >I've never had trouble with the 9-speed links - on a dirty chain, my main >problem is finding it! I just squeeze the plates together, then hold the >link either side and push them inward. > >But the 8-speed version seems much tighter when new. I've had to do a >lot of pushing, wiggling and swearing to get them on and off sometimes. > All my chains are 9-spd. _ Booker C. Bense             Date: 25 Jun 2007 10:44:22 From: Tom Nakashima Subject: Re: Safe to lengthen a chain? >> >>But the 8-speed version seems much tighter when new. I've had to do a >>lot of pushing, wiggling and swearing to get them on and off sometimes. >> I had the same problem. What's happening is they're trying to use the 9sp power-link on the 8sp chain. The 8sp chain is slightly wider than the 9sp chain, so I ended up using the 8sp chain without the power-link. -tom               Date: 26 Jun 2007 09:34:05 From: Michael Warner Subject: Re: Safe to lengthen a chain? On Mon, 25 Jun 2007 10:44:22 -0700, Tom Nakashima wrote: > I had the same problem. What's happening is they're trying to use the > 9sp power-link on the 8sp chain. The 8sp chain is slightly wider than > the 9sp chain, so I ended up using the 8sp chain without the power-link. IIRC it's actually stamped "8" and looks a little wider, but that's only from memory. -- Home page: http://members.westnet.com.au/mvw       Date: 23 Jun 2007 20:45:09 From: Steve Gravrock Subject: Re: Safe to lengthen a chain? On 2007-06-23, jobst.brandt@stanfordalumni.org <jobst.brandt@stanfordalumni.org > wrote: > PowerLinks take much power to disengage on a used (dirty) chain. I > found that using pliers diagonally, end-to-end of the link, compresses > it in both directions enough to open it. That is, if you need to open > the chain in the field, as one does if a stick damages the derailleur, > a CPR-9 chain tool is the way to do it. You probably cannot get a > PowerLink open without tools. I've had the same experience with 8-speed PowerLinks. I run some kind of SRAM 8-speed chain, probably the pc48, on my snow bike and opening the PowerLink is a nightmare. The 9 speed PowerLinks are a different animal though. They open very easily without tools even when the chain is dirty. I don't know what makes the difference, but it's pretty dramatic.         Date: 23 Jun 2007 22:53:30 From: Subject: Re: Safe to lengthen a chain? Steve Gravrock writes: >> PowerLinks take much power to disengage on a used (dirty) chain. I >> found that using pliers diagonally, end-to-end of the link, >> compresses it in both directions enough to open it. That is, if >> you need to open the chain in the field, as one does if a stick >> damages the derailleur, a CPR-9 chain tool is the way to do it. >> You probably cannot get a PowerLink open without tools. > I've had the same experience with 8-speed PowerLinks. I run some > kind of SRAM 8-speed chain, probably the pc48, on my snow bike and > opening the PowerLink is a nightmare. The 9 speed PowerLinks are a > different animal though. They open very easily without tools even > when the chain is dirty. I don't know what makes the difference, but > it's pretty dramatic. The 8sp PowerLink has a stepped recess in the 'hole' plate and to disengage the pins, the 'hole' plate must be pressed inward the depth of the tiny ridge that fits in the pin groove and retains the pins. If you have a close-up view of that link similar to the one at: http://www.speedgoat.com/product.asp?part=38807&cat=80&brand=55 or: http://www.sheldonbrown.com/harris/chains.html the reason for easier separation should be apparent. I Don't have one and would need to visit the local bicycle shop to investigate. Jobst Brandt           Date: 25 Jun 2007 08:45:29 From: Peter Cole Subject: Re: Safe to lengthen a chain? jobst.brandt@stanfordalumni.org wrote: > Steve Gravrock writes: > >>> PowerLinks take much power to disengage on a used (dirty) chain. I >>> found that using pliers diagonally, end-to-end of the link, >>> compresses it in both directions enough to open it. That is, if >>> you need to open the chain in the field, as one does if a stick >>> damages the derailleur, a CPR-9 chain tool is the way to do it. >>> You probably cannot get a PowerLink open without tools. > >> I've had the same experience with 8-speed PowerLinks. I run some >> kind of SRAM 8-speed chain, probably the pc48, on my snow bike and >> opening the PowerLink is a nightmare. The 9 speed PowerLinks are a >> different animal though. They open very easily without tools even >> when the chain is dirty. I don't know what makes the difference, but >> it's pretty dramatic. > > The 8sp PowerLink has a stepped recess in the 'hole' plate and to > disengage the pins, the 'hole' plate must be pressed inward the depth > of the tiny ridge that fits in the pin groove and retains the pins. > If you have a close-up view of that link similar to the one at: > > http://www.speedgoat.com/product.asp?part=38807&cat=80&brand=55 > > or: > > http://www.sheldonbrown.com/harris/chains.html > > the reason for easier separation should be apparent. I Don't have one > and would need to visit the local bicycle shop to investigate. > > Jobst Brandt The older Craig "Super Link" didn't have a stepped recess in the hole and as a result was much easier to disconnect. I think the SRAM design is a bad one, destroying most of the convenience of a quick link.             Date: 25 Jun 2007 18:22:01 From: Subject: Re: Safe to lengthen a chain? Peter Cole writes: >>>> PowerLinks take much power to disengage on a used (dirty) chain. >>>> I found that using pliers diagonally, end-to-end of the link, >>>> compresses it in both directions enough to open it. That is, if >>>> you need to open the chain in the field, as one does if a stick >>>> damages the derailleur, a CPR-9 chain tool is the way to do it. >>>> You probably cannot get a PowerLink open without tools. >>> I've had the same experience with 8-speed PowerLinks. I run some >>> kind of SRAM 8-speed chain, probably the pc48, on my snow bike and >>> opening the PowerLink is a nightmare. The 9 speed PowerLinks are a >>> different animal though. They open very easily without tools even >>> when the chain is dirty. I don't know what makes the difference, >>> but it's pretty dramatic. >> The 8sp PowerLink has a stepped recess in the 'hole' plate and to >> disengage the pins, the 'hole' plate must be pressed inward the >> depth of the tiny ridge that fits in the pin groove and retains the >> pins. If you have a close-up view of that link similar to the one >> at: http://www.speedgoat.com/product.asp?part=38807&cat=80&brand=55 >> or: >> http://www.sheldonbrown.com/harris/chains.html >> the reason for easier separation should be apparent. I Don't have >> one and would need to visit the local bicycle shop to investigate. > The older Craig "Super Link" didn't have a stepped recess in the > hole and as a result was much easier to disconnect. I think the SRAM > design is a bad one, destroying most of the convenience of a quick > link. As you see, even the stepped hole didn't prevent my clean new chain from disengaging the link when the chain skipped, so the stepped hole only helps when the chain has grit in it and then it is a bear to open. That is why I don't use one, besides the reason for using one isn't really there for me. In the event of a derailleur failure, the chain must be judiciously shortened for a direct run between appropriate sprockets. Another rider and I have had this occur, and the chain tool is what was needed. Jobst Brandt               Date: 25 Jun 2007 20:54:20 From: Sandy Subject: Re: Safe to lengthen a chain? Dans le message de news:468007c9$0$14147$742ec2ed@news.sonic.net, jobst.brandt@stanfordalumni.org <jobst.brandt@stanfordalumni.org > a réfléchi, et puis a déclaré : > Peter Cole writes: > >>>>> PowerLinks take much power to disengage on a used (dirty) chain. >>>>> I found that using pliers diagonally, end-to-end of the link, >>>>> compresses it in both directions enough to open it. That is, if >>>>> you need to open the chain in the field, as one does if a stick >>>>> damages the derailleur, a CPR-9 chain tool is the way to do it. >>>>> You probably cannot get a PowerLink open without tools. > >>>> I've had the same experience with 8-speed PowerLinks. I run some >>>> kind of SRAM 8-speed chain, probably the pc48, on my snow bike and >>>> opening the PowerLink is a nightmare. The 9 speed PowerLinks are a >>>> different animal though. They open very easily without tools even >>>> when the chain is dirty. I don't know what makes the difference, >>>> but it's pretty dramatic. > >>> The 8sp PowerLink has a stepped recess in the 'hole' plate and to >>> disengage the pins, the 'hole' plate must be pressed inward the >>> depth of the tiny ridge that fits in the pin groove and retains the >>> pins. If you have a close-up view of that link similar to the one >>> at: > > http://www.speedgoat.com/product.asp?part=38807&cat=80&brand=55 > >>> or: > >>> http://www.sheldonbrown.com/harris/chains.html > >>> the reason for easier separation should be apparent. I Don't have >>> one and would need to visit the local bicycle shop to investigate. > >> The older Craig "Super Link" didn't have a stepped recess in the >> hole and as a result was much easier to disconnect. I think the SRAM >> design is a bad one, destroying most of the convenience of a quick >> link. > > As you see, even the stepped hole didn't prevent my clean new chain > from disengaging the link when the chain skipped, so the stepped hole > only helps when the chain has grit in it and then it is a bear to > open. That is why I don't use one, besides the reason for using one > isn't really there for me. In the event of a derailleur failure, the > chain must be judiciously shortened for a direct run between > appropriate sprockets. Another rider and I have had this occur, and > the chain tool is what was needed. > > Jobst Brandt Everyone gets to be a klutz sometime or other.   Date: 23 Jun 2007 06:19:03 From: Kenny Subject: Re: Safe to lengthen a chain? On Jun 23, 1:51 am, "bw2...@yahoo.com" <bw2...@yahoo.com > wrote: > I cut a new PC59 chain one link too short. Is it safe to add that > link back on? > > Thanks. To be absolutely safe use a snap link or powerlink. That being said, I have reconnected odd lengths of chain together to get to the correct length. Those bits of chain were "carefully" delinked to begin with, meaning the connecting pin was never pushed out all the way through. When reconnecting the chain links be very careful that the pins are pushed back flush with the side plates. Once I did a two week tour of northern Italy with a PC59 chain that was originally too short for my triple setup. I used a Campy 10sp (2002) chain with 5 links that I attached to the PC59 to get the proper length. I used that chain for about 5000km. Never had a problem. Oh, by the way, if you decide to try this it's a good idea to bring along those snap links or a chain tool just in case.     Date: 23 Jun 2007 14:45:27 From: still me Subject: Re: Safe to lengthen a chain? On Sat, 23 Jun 2007 06:19:03 -0700, Kenny <Postoasted@gmail.com > wrote: >On Jun 23, 1:51 am, "bw2...@yahoo.com" <bw2...@yahoo.com> wrote: >> I cut a new PC59 chain one link too short. Is it safe to add that >> link back on? >> >> Thanks. > >To be absolutely safe use a snap link or powerlink. Retro oriented question: Why is this true with "modern" chains? Do they peen the heads larger ? If using SRAM chains, at what point in the line does this become an issue - pc48? 58?       Date: 24 Jun 2007 16:37:50 From: A Muzi Subject: Re: Safe to lengthen a chain? >> "bw2...@yahoo.com" <bw2...@yahoo.com> wrote: >>> I cut a new PC59 chain one link too short. Is it safe to add that >>> link back on? > Kenny <Postoasted@gmail.com> wrote: >> To be absolutely safe use a snap link or powerlink. still me wrote: > Retro oriented question: Why is this true with "modern" chains? Do > they peen the heads larger ? > If using SRAM chains, at what point in the line does this become an > issue - pc48? 58? Because the rivets fit more tightly and they don't hang out as far as early chain. Rivet error = rider injury so why not use the snap link? Pretty much all 8-9-10 chain. -- Andrew Muzi www.yellowjersey.org Open every day since 1 April, 1971   Date: 23 Jun 2007 05:39:52 From: Qui si parla Campagnolo Subject: Re: Safe to lengthen a chain? On Jun 22, 11:51 am, "bw2...@yahoo.com" <bw2...@yahoo.com > wrote: > I cut a new PC59 chain one link too short. Is it safe to add that > link back on? > > Thanks. No but you can use another snap link.   Date: 22 Jun 2007 22:27:55 From: Johnny Sunset Subject: Re: Safe to lengthen a chain? On Jun 22, 10:35 pm, Lou Holtman wrote: > Kinky Cowboy wrote: > > On Fri, 22 Jun 2007 10:51:11 -0700, "bw2"wrote: > > >> I cut a new PC59 chain one link too short. Is it safe to add that > >> link back on? > > >> Thanks. > > > Use a second Powerlink > > ??? Inner and outer? Some of my bikes have chains with three (3) Powerlinks with no ill effects. -- Tom Sherman - Holstein-Friesland Bovinia The weather is here, wish you were beautiful     Date: 24 Jun 2007 23:52:19 From: Michael Warner Subject: Re: Safe to lengthen a chain? On Fri, 22 Jun 2007 22:27:55 -0700, Johnny Sunset wrote: > Some of my bikes have chains with three (3) Powerlinks with no ill > effects. Except that the resulting chain is ridiculously long and heavy :-) -- Home page: http://members.westnet.com.au/mvw   Date: 23 Jun 2007 00:38:43 From: Kinky Cowboy Subject: Re: Safe to lengthen a chain? On Fri, 22 Jun 2007 10:51:11 -0700, "bw2117@yahoo.com" <bw2117@yahoo.com > wrote: >I cut a new PC59 chain one link too short. Is it safe to add that >link back on? > >Thanks. Use a second Powerlink Kinky Cowboy* *Batteries not included May contain traces of nuts Your milage may vary     Date: 23 Jun 2007 05:35:44 From: Lou Holtman Subject: Re: Safe to lengthen a chain? Kinky Cowboy wrote: > On Fri, 22 Jun 2007 10:51:11 -0700, "bw2117@yahoo.com" > <bw2117@yahoo.com> wrote: > >> I cut a new PC59 chain one link too short. Is it safe to add that >> link back on? >> >> Thanks. > > Use a second Powerlink ??? Inner and outer? Lou -- Posted by news://news.nb.nu (http://www.nb.nu)       Date: 24 Jun 2007 15:33:55 From: A Muzi Subject: Re: Safe to lengthen a chain? >> "bw2117@yahoo.com" <bw2117@yahoo.com> wrote: >>> I cut a new PC59 chain one link too short. Is it safe to add that >>> link back on? > Kinky Cowboy wrote: >> Use a second Powerlink Lou Holtman wrote: > ??? Inner and outer? Use the scrap innie with a second Powerlink, as Kinky noted. -- Andrew Muzi www.yellowjersey.org Open every day since 1 April, 1971