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Date: 21 Oct 2007 13:52:07
From: Duncan Smith
Subject: Help! Fitting a rear mech
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I tried to change the (suspected bent) LX rear mech to one of the newer less protruding XT ones on the MTB. Everything goes good when the chain is on the biggest ring - get full range of the cassette from the indexed pod selector - no problem. But, on the middle chain-ring, when the smallest outermost sprockets are selected the pulley cage doesn't take up the enough slack. When the granny-gear ring is selected the chain is almost dragging on the floor. Chain length is sufficient to enable the large ring and large sprocket (with having to pull on the mech about one links worth). The pulley cage is sprung so that it does pull the chain back - so I don't think it's mounted incorrectly or anything. Any ideas what I might have done wrong? Thanks, Duncan
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Date: 28 Oct 2007 19:45:12
From: Duncan Smith
Subject: Re: Help! Fitting a rear mech
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> > > r.b.t. protocol violation: > > Only Gene is allowed to call a gear changer a 'deray'. > > butbutbut [2], it is OK as long as it is footnoted as a gdanielsism. > > [1] Gratuitous gdanielsism. > [2] ibid. > I have no idea what either of you are talking about! Sorry... Regards, Duncan
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Date: 28 Oct 2007 14:48:05
From: Tom Sherman
Subject: Re: Help! Fitting a rear mech
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Duncan Smith wrote: >>> r.b.t. protocol violation: >>> Only Gene is allowed to call a gear changer a 'deray'. >> butbutbut [2], it is OK as long as it is footnoted as a gdanielsism. >> >> [1] Gratuitous gdanielsism. >> [2] ibid. >> > > I have no idea what either of you are talking about! Sorry... Google Groups search "datakoll". -- Tom Sherman - Holstein-Friesland Bovinia When did ignorance of biology become a "family value"?
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Date: 24 Oct 2007 11:11:19
From: velodancer
Subject: Re: Help! Fitting a rear mech
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> Boy do I feel silly! I took the mech off to try and find GS or SGS > serial code and then replaced it to take it to the shop. Only when I > replaced it I noticed the deray housing was now touching the drop out > and the chain cage was angled back much further - fitted the chain did > the H/L/Index settings - works a treat. At least I found it out > before returning it to the shop. Glad you solved your problem. There are some significant differences in the new Shadow derailleurs though. Besides the low profile, there are three other major changes: a more direct cable pull (reduced loop in the cable housing), removal of the B tension spring, and centering of the guide pulley on the cage pivot. The direct cable routing is clearly better. The next two changes are only an advantage for Horst link bikes as they prevent the derailleur from hitting the chainstay. This issue is clearly demonstrated by the infamous videos of SRAM versus Shimano rear derailleurs: http://www.youtube.com/watch?v=tYL_Vc4hU1U http://www.youtube.com/watch?v=NYKvCLC23ww I talked to a senior Shimano guy at the show and he said that shifting is not improved by these changes. Most customers with OE drivetrains will not be able to notice any difference other than reduced ability to misadjust cable tension (for example good shifting will occur only within one turn of the barrel adjuster rather then two turns). I can only assume that Specialized is a large enough customer to make this reduction in shifting quality worthwhile enough to raise eyebrows at apparent adoption of SRAM derailleur design. As the B pivot is now essentially fixed, this required two other changes in this derailleur design. Because the derailleur can no longer "float", it cannot follow the change in cog size as accurately. This is exacerbated by the lack of an offset guide pulley. Thus the cage angle has been significantly increased compared to help it track the cogs better. This makes it less flexible for a variety of cog sets and indeed Shimano specs this derailleur as being for 11-32/34t clusters only. For a similar reason, it does not have the inherent chain wrap capacity of derailleurs with B tension springs. Thus you will notice that the cage is significantly longer than the old design to compensate. In fact, the long cage version is probably the longest cage I have ever seen. Because of the lack of the B spring, tension of the pulley spring had to be increased. The Shimano rep told me that this translates into a 15 percent higher force required on the cable (probably unnoticeable but still significant). I purchased the XT Shadow long cage before I went to Interbike based on what I thought were real design improvements at the time. After Interbike I wished I hadn't, particularly after my trial last week of two very different derailleurs. As background, I have a non OE very wide range (9-34t) cogset with custom cog selection (Shimano). As such, my setup is ideal for testing derailleur's abilities on marginal systems. I'd been using a SRAM X-O derailleur for some months. Switching to an older XT derailleur (and appropriate shifter) brought about significant gains. While subjective, I would say shifting improved about 20 percent. In addition, one thing often noted about SRAM derailleurs is that upshifting (to a smaller cog) is done with a noticeable clunk, both audible and tactile. Because of the way my XT B spring derailleur follows the cogs closer, upshifts are much smoother. If performance was otherwise the same, this one factor would be enough for me to switch. As a result of this, I don't even see the point of trialing my new Shadow XT for my purposes (I'll probably sell it on eBay). For others, you would have to consider carefully your choices. Horst link owner? That is a no brainer. Often hit your derailleur on protrusions? Maybe. I looked at my older derailleurs and noticed a number of dings. Don't have a wide cluster? Then no. I wish Shimano would put the more direct cable routing on all their derailleurs but unless you are unwilling to go the Avid Rollamajig route, that shouldn't be a major factor. SRAM versus the Shadow? The increased cable pull of the SRAM is a minor technical advantage. One other thing to consider when switching from standard Shimano to SRAM or the new Shadow if you have a full suspension bike is proper chain length. You will likely need to add a chain link or two. SRAM derailleurs have a reputation for self destruction on the trail. I'm convinced this happens because of chain growth at full bump. Derailleurs with a B tension spring have much better wrap and ability to shrug off poor chain length selection. On other thing noteworthy I've discovered with my less than optimal setup is that Shimano chains shift better on Shimano clusters than SRAM chains. It was very minor but noticeable. I was very surprised by this and almost didn't bother trialing the Shimano chain because I could not see a visual difference in inner plate profile - they looked absolutely identical.
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Date: 23 Oct 2007 10:12:48
From: Duncan Smith
Subject: Re: Help! Fitting a rear mech
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On Oct 21, 11:57 pm, datakoll <datak...@yahoo.com > wrote: > - delete irrelevant text - > > anyway, I was under the impression a chain going around large CR and > large cog could be one inch - two link sections - too long: maybe two. > do you have a sram powerlink on hand? so the chain can be chopped and > fitted? and a 5 foot chain board to lay the chain on for link counting? Boy do I feel silly! I took the mech off to try and find GS or SGS serial code and then replaced it to take it to the shop. Only when I replaced it I noticed the deray housing was now touching the drop out and the chain cage was angled back much further - fitted the chain did the H/L/Index settings - works a treat. At least I found it out before returning it to the shop. Thanks for all the suggestions.. Duncan
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Date: 23 Oct 2007 14:23:17
From: A Muzi
Subject: Re: Help! Fitting a rear mech
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> datakoll <datak...@yahoo.com> wrote: >> - delete irrelevant text - >> anyway, I was under the impression a chain going around large CR and >> large cog could be one inch - two link sections - too long: maybe two. >> do you have a sram powerlink on hand? so the chain can be chopped and >> fitted? and a 5 foot chain board to lay the chain on for link counting? Duncan Smith wrote: > Boy do I feel silly! I took the mech off to try and find GS or SGS > serial code and then replaced it to take it to the shop. Only when I > replaced it I noticed the deray housing was now touching the drop out > and the chain cage was angled back much further - fitted the chain did > the H/L/Index settings - works a treat. At least I found it out > before returning it to the shop. r.b.t. protocol violation: Only Gene is allowed to call a gear changer a 'deray'. -- Andrew Muzi www.yellowjersey.org Open every day since 1 April, 1971
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Date: 23 Oct 2007 20:56:44
From: Tom Sherman
Subject: Re: Help! Fitting a rear mech
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Andrew Muzi mused: - delete unimportant text - [1] > Duncan Smith wrote: >> Boy do I feel silly! I took the mech off to try and find GS or SGS >> serial code and then replaced it to take it to the shop. Only when I >> replaced it I noticed the deray housing was now touching the drop out >> and the chain cage was angled back much further - fitted the chain did >> the H/L/Index settings - works a treat. At least I found it out >> before returning it to the shop. > > r.b.t. protocol violation: > Only Gene is allowed to call a gear changer a 'deray'. butbutbut [2], it is OK as long as it is footnoted as a gdanielsism. [1] Gratuitous gdanielsism. [2] ibid. -- Tom Sherman - Holstein-Friesland Bovinia Beer - It's not just for breakfast anymore!
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Date: 21 Oct 2007 22:57:24
From: datakoll
Subject: Re: Help! Fitting a rear mech
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- delete irrelevant text - anyway, I was under the impression a chain going around large CR and large cog could be one inch - two link sections - too long: maybe two. do you have a sram powerlink on hand? so the chain can be chopped and fitted? and a 5 foot chain board to lay the chain on for link counting?
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Date: 21 Oct 2007 22:50:50
From: datakoll
Subject: Re: Help! Fitting a rear mech
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loosen the cable screw, with system in small outboard cog, pull cable with vise grips { clamp jaws on cable end just snugly then use screw to tighten} tight, pull deray cage to cycles rearward, then with third hand tighten (still pulling cable tight ) cabe screw, fastening taught cable. That's avariable adjustment in conjunction with the deray screw found at the frame/deray area mounted on the deray/frame bolt bushing. Screw that screw in but don't force it. Find a way to not force it and screw in.
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Date: 21 Oct 2007 15:25:12
From: A Muzi
Subject: Re: Help! Fitting a rear mech
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Duncan Smith wrote: > I tried to change the (suspected bent) LX rear mech to one of the > newer less protruding XT ones on the MTB. Everything goes good when > the chain is on the biggest ring - get full range of the cassette from > the indexed pod selector - no problem. > > But, on the middle chain-ring, when the smallest outermost sprockets > are selected the pulley cage doesn't take up the enough slack. When > the granny-gear ring is selected the chain is almost dragging on the > floor. Chain length is sufficient to enable the large ring and large > sprocket (with having to pull on the mech about one links worth). > > The pulley cage is sprung so that it does pull the chain back - so I > don't think it's mounted incorrectly or anything. Any ideas what I > might have done wrong? Did you get the short "GS" or the long "SGS" model? -- Andrew Muzi www.yellowjersey.org Open every day since 1 April, 1971
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Date: 21 Oct 2007 13:08:53
From: landotter
Subject: Re: Help! Fitting a rear mech
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On Oct 21, 2:05 pm, Duncan Smith <DSmith1...@googlemail.com > wrote: > On Oct 21, 3:49 pm, Hank Wirtz <h...@wirtznet.net> wrote: > > > > > On Oct 21, 6:52 am, Duncan Smith <DSmith1...@googlemail.com> wrote: > > > > I tried to change the (suspected bent) LX rear mech to one of the > > > newer less protruding XT ones on the MTB. Everything goes good when > > > the chain is on the biggest ring - get full range of the cassette from > > > the indexed pod selector - no problem. > > > > But, on the middle chain-ring, when the smallest outermost sprockets > > > are selected the pulley cage doesn't take up the enough slack. When > > > the granny-gear ring is selected the chain is almost dragging on the > > > floor. Chain length is sufficient to enable the large ring and large > > > sprocket (with having to pull on the mech about one links worth). > > > > The pulley cage is sprung so that it does pull the chain back - so I > > > don't think it's mounted incorrectly or anything. Any ideas what I > > > might have done wrong? > > > > Thanks, > > > > Duncan > > > Check the part number of the new one. Does it say GS or SGS? If it's > > GS, you got the medium cage model, which probably doesn't have enough > > wrap capacity. > > Thrown the box away now, but I'm pretty sure it was a GS. The bike's > a 2007 Rock-hopper. Where would incompatibility arise from - the > frame, chain-rings? > > Thanks, > > Duncan The gearing in general. Your medium cage GS doesn't have the capacity for your particular gearing. See the difference: http://www.starbike.com/images/Shimano/Deore_LX/hires/RD-M580-SGS.jpg http://www.starbike.com/images/Shimano/Deore_LX/hires/RD-M580-GS.jpg
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Date: 21 Oct 2007 20:35:10
From: Steve Gravrock
Subject: Re: Help! Fitting a rear mech
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On 2007-10-21, landotter <landotter@gmail.com > wrote: > On Oct 21, 2:05 pm, Duncan Smith <DSmith1...@googlemail.com> wrote: >> Thrown the box away now, but I'm pretty sure it was a GS. The bike's >> a 2007 Rock-hopper. Where would incompatibility arise from - the >> frame, chain-rings? >> >> Thanks, >> >> Duncan > > The gearing in general. Your medium cage GS doesn't have the capacity > for your particular gearing. > > See the difference: > > http://www.starbike.com/images/Shimano/Deore_LX/hires/RD-M580-SGS.jpg > http://www.starbike.com/images/Shimano/Deore_LX/hires/RD-M580-GS.jpg Why does Shimano even bother to make medium cage mountain bike derailers? Aside from the 1x9 crowd, which isn't big enough for Shimano to bother with, I don't see anything newer than my old 7 speed that could use one of those. I suppose you could put one on a road bike, but that market's already taken care of.
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Date: 21 Oct 2007 15:50:47
From: A Muzi
Subject: Re: Help! Fitting a rear mech
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>> Duncan Smith <DSmith1...@googlemail.com> wrote: >>> Thrown the box away now, but I'm pretty sure it was a GS. The bike's >>> a 2007 Rock-hopper. Where would incompatibility arise from - the >>> frame, chain-rings? > landotter <landotter@gmail.com> wrote: >> The gearing in general. Your medium cage GS doesn't have the capacity >> for your particular gearing. >> See the difference: >> http://www.starbike.com/images/Shimano/Deore_LX/hires/RD-M580-SGS.jpg >> http://www.starbike.com/images/Shimano/Deore_LX/hires/RD-M580-GS.jpg Steve Gravrock wrote: > Why does Shimano even bother to make medium cage mountain bike > derailers? Aside from the 1x9 crowd, which isn't big enough for Shimano > to bother with, I don't see anything newer than my old 7 speed that > could use one of those. I suppose you could put one on a road bike, but > that market's already taken care of. As Peter quotes often, "It's for selling". In any LBS, a popular question is 'which is lighter?' among other queries of similar depth. -- Andrew Muzi www.yellowjersey.org Open every day since 1 April, 1971
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Date: 22 Oct 2007 08:03:01
From: M-gineering
Subject: Re: Help! Fitting a rear mech
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A Muzi wrote: >>> Duncan Smith <DSmith1...@googlemail.com> wrote: >>>> Thrown the box away now, but I'm pretty sure it was a GS. The bike's >>>> a 2007 Rock-hopper. Where would incompatibility arise from - the >>>> frame, chain-rings? > >> landotter <landotter@gmail.com> wrote: >>> The gearing in general. Your medium cage GS doesn't have the capacity >>> for your particular gearing. >>> See the difference: >>> http://www.starbike.com/images/Shimano/Deore_LX/hires/RD-M580-SGS.jpg >>> http://www.starbike.com/images/Shimano/Deore_LX/hires/RD-M580-GS.jpg > > Steve Gravrock wrote: >> Why does Shimano even bother to make medium cage mountain bike >> derailers? Aside from the 1x9 crowd, which isn't big enough for Shimano >> to bother with, I don't see anything newer than my old 7 speed that >> could use one of those. I suppose you could put one on a road bike, but >> that market's already taken care of. > > As Peter quotes often, "It's for selling". > In any LBS, a popular question is 'which is lighter?' among other > queries of similar depth. If you're stuck in flatland, 28 is a BIG cog and a medium cage is fine (with a road cassette ;)) -- /Marten info(apestaartje)m-gineering(punt)nl
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Date: 21 Oct 2007 19:05:21
From: Duncan Smith
Subject: Re: Help! Fitting a rear mech
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On Oct 21, 3:49 pm, Hank Wirtz <h...@wirtznet.net > wrote: > On Oct 21, 6:52 am, Duncan Smith <DSmith1...@googlemail.com> wrote: > > > > > I tried to change the (suspected bent) LX rear mech to one of the > > newer less protruding XT ones on the MTB. Everything goes good when > > the chain is on the biggest ring - get full range of the cassette from > > the indexed pod selector - no problem. > > > But, on the middle chain-ring, when the smallest outermost sprockets > > are selected the pulley cage doesn't take up the enough slack. When > > the granny-gear ring is selected the chain is almost dragging on the > > floor. Chain length is sufficient to enable the large ring and large > > sprocket (with having to pull on the mech about one links worth). > > > The pulley cage is sprung so that it does pull the chain back - so I > > don't think it's mounted incorrectly or anything. Any ideas what I > > might have done wrong? > > > Thanks, > > > Duncan > > Check the part number of the new one. Does it say GS or SGS? If it's > GS, you got the medium cage model, which probably doesn't have enough > wrap capacity. Thrown the box away now, but I'm pretty sure it was a GS. The bike's a 2007 Rock-hopper. Where would incompatibility arise from - the frame, chain-rings? Thanks, Duncan
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Date: 21 Oct 2007 15:31:35
From: A Muzi
Subject: Re: Help! Fitting a rear mech
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>> Duncan Smith <DSmith1...@googlemail.com> wrote: >>> I tried to change the (suspected bent) LX rear mech to one of the >>> newer less protruding XT ones on the MTB. Everything goes good when >>> the chain is on the biggest ring - get full range of the cassette from >>> the indexed pod selector - no problem. >>> But, on the middle chain-ring, when the smallest outermost sprockets >>> are selected the pulley cage doesn't take up the enough slack. When >>> the granny-gear ring is selected the chain is almost dragging on the >>> floor. Chain length is sufficient to enable the large ring and large >>> sprocket (with having to pull on the mech about one links worth). >>> The pulley cage is sprung so that it does pull the chain back - so I >>> don't think it's mounted incorrectly or anything. Any ideas what I >>> might have done wrong? > Hank Wirtz <h...@wirtznet.net> wrote: >> Check the part number of the new one. Does it say GS or SGS? If it's >> GS, you got the medium cage model, which probably doesn't have enough >> wrap capacity. Duncan Smith wrote: > Thrown the box away now, but I'm pretty sure it was a GS. The bike's > a 2007 Rock-hopper. Where would incompatibility arise from - the > frame, chain-rings? Measure the distance between pulleys on old and new. You may have replaced an "SGS" with a "GS" -- Andrew Muzi www.yellowjersey.org Open every day since 1 April, 1971
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Date: 21 Oct 2007 20:08:16
From: Steve Gravrock
Subject: Re: Help! Fitting a rear mech
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On 2007-10-21, Duncan Smith <DSmith1974@googlemail.com > wrote: > On Oct 21, 3:49 pm, Hank Wirtz <h...@wirtznet.net> wrote: >> Check the part number of the new one. Does it say GS or SGS? If it's >> GS, you got the medium cage model, which probably doesn't have enough >> wrap capacity. > > Thrown the box away now, but I'm pretty sure it was a GS. The bike's > a 2007 Rock-hopper. Where would incompatibility arise from - the > frame, chain-rings? It comes from the overall range of gearing. The cage length determines how much chain slack it can take up. For a normal mountain bike drivetrain you need the long cage SGS model.
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Date: 21 Oct 2007 18:59:38
From: Duncan Smith
Subject: Re: Help! Fitting a rear mech
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On Oct 21, 3:42 pm, landotter <landot...@gmail.com > wrote: > On Oct 21, 8:52 am, Duncan Smith <DSmith1...@googlemail.com> wrote: > > > I tried to change the (suspected bent) LX rear mech to one of the > > newer less protruding XT ones on the MTB. Everything goes good when > > the chain is on the biggest ring - get full range of the cassette from > > the indexed pod selector - no problem. > > > But, on the middle chain-ring, when the smallest outermost sprockets > > are selected the pulley cage doesn't take up the enough slack. When > > the granny-gear ring is selected the chain is almost dragging on the > > floor. Chain length is sufficient to enable the large ring and large > > sprocket (with having to pull on the mech about one links worth). > > > The pulley cage is sprung so that it does pull the chain back - so I > > don't think it's mounted incorrectly or anything. Any ideas what I > > might have done wrong? > > Increase b-screw tension which tightens the d=E9railleur pivot spring. It was a tight as it would go...
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Date: 21 Oct 2007 18:58:46
From: Duncan Smith
Subject: Re: Help! Fitting a rear mech
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On Oct 21, 3:31 pm, Lou Holtman <lholremovet...@planet.nl > wrote: > Duncan Smith wrote: > > I tried to change the (suspected bent) LX rear mech to one of the > > newer less protruding XT ones on the MTB. Everything goes good when > > the chain is on the biggest ring - get full range of the cassette from > > the indexed pod selector - no problem. > > > But, on the middle chain-ring, when the smallest outermost sprockets > > are selected the pulley cage doesn't take up the enough slack. When > > the granny-gear ring is selected the chain is almost dragging on the > > floor. Chain length is sufficient to enable the large ring and large > > sprocket (with having to pull on the mech about one links worth). > > > The pulley cage is sprung so that it does pull the chain back - so I > > don't think it's mounted incorrectly or anything. Any ideas what I > > might have done wrong? > > Is your chainlength really correct, compared to the 'old sitiuation'? > Same length as the old one exactly, then I took a link out and found it was a bit of a stretch when on the largest ring and sprocket - so put it back again...
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Date: 21 Oct 2007 07:49:31
From: Hank Wirtz
Subject: Re: Help! Fitting a rear mech
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On Oct 21, 6:52 am, Duncan Smith <DSmith1...@googlemail.com > wrote: > I tried to change the (suspected bent) LX rear mech to one of the > newer less protruding XT ones on the MTB. Everything goes good when > the chain is on the biggest ring - get full range of the cassette from > the indexed pod selector - no problem. > > But, on the middle chain-ring, when the smallest outermost sprockets > are selected the pulley cage doesn't take up the enough slack. When > the granny-gear ring is selected the chain is almost dragging on the > floor. Chain length is sufficient to enable the large ring and large > sprocket (with having to pull on the mech about one links worth). > > The pulley cage is sprung so that it does pull the chain back - so I > don't think it's mounted incorrectly or anything. Any ideas what I > might have done wrong? > > Thanks, > > Duncan Check the part number of the new one. Does it say GS or SGS? If it's GS, you got the medium cage model, which probably doesn't have enough wrap capacity.
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Date: 21 Oct 2007 07:42:55
From: landotter
Subject: Re: Help! Fitting a rear mech
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On Oct 21, 8:52 am, Duncan Smith <DSmith1...@googlemail.com > wrote: > I tried to change the (suspected bent) LX rear mech to one of the > newer less protruding XT ones on the MTB. Everything goes good when > the chain is on the biggest ring - get full range of the cassette from > the indexed pod selector - no problem. > > But, on the middle chain-ring, when the smallest outermost sprockets > are selected the pulley cage doesn't take up the enough slack. When > the granny-gear ring is selected the chain is almost dragging on the > floor. Chain length is sufficient to enable the large ring and large > sprocket (with having to pull on the mech about one links worth). > > The pulley cage is sprung so that it does pull the chain back - so I > don't think it's mounted incorrectly or anything. Any ideas what I > might have done wrong? Increase b-screw tension which tightens the d=E9railleur pivot spring.
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Date: 21 Oct 2007 16:31:34
From: Lou Holtman
Subject: Re: Help! Fitting a rear mech
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Duncan Smith wrote: > I tried to change the (suspected bent) LX rear mech to one of the > newer less protruding XT ones on the MTB. Everything goes good when > the chain is on the biggest ring - get full range of the cassette from > the indexed pod selector - no problem. > > But, on the middle chain-ring, when the smallest outermost sprockets > are selected the pulley cage doesn't take up the enough slack. When > the granny-gear ring is selected the chain is almost dragging on the > floor. Chain length is sufficient to enable the large ring and large > sprocket (with having to pull on the mech about one links worth). > > The pulley cage is sprung so that it does pull the chain back - so I > don't think it's mounted incorrectly or anything. Any ideas what I > might have done wrong? Is your chainlength really correct, compared to the 'old sitiuation'? Lou -- Posted by news://news.nb.nu (http://www.nb.nu)
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