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Main
Date: 17 Jul 2007 05:19:51
From: mark
Subject: spoke tension
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Could someone recommend the proper spoke tension for a rear wheel built
with a Velocity Aerohead OC rim?
TIA,
mark
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Date: 23 Jul 2007 08:25:29
From: andresmuro@aol.com
Subject: Re: spoke tension
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On Jul 23, 7:14 am, jim beam <spamvor...@bad.example.net > wrote:
> Ben C wrote:
> > On 2007-07-22, andresm...@aol.com <andresm...@aol.com> wrote:
> > [...]
> >> Problem is that the other techies in the group seem to agree with XY's
> >> theories and not with PQs theories.
>
> > If you read between the lines a bit the disagreements between XY and PQ
> > on how to actually build a wheel are not actually so great.
>
> except that i'm not interested in telling people how to build wheels. i
> /am/ interested in making sure people correctly understand materials
> theory though,
>
>
You want to teach us material's theory? How do we know that you are
qualified to teach it? Again, an expert in a field must be able to
note his claims with credibility, citations past accomplishments, etc.
Is there anyone else in this group that knows about materials theory
that can substantiate your claims? Any engineers or physicists here
that know about materials theory that can agree that JB is talking
nonesense? Are you the only expert that has figured this out and you
are misunderstood?
Andres
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Date: 23 Jul 2007 20:50:16
From: jim beam
Subject: Re: spoke tension
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andresmuro@aol.com wrote:
> On Jul 23, 7:14 am, jim beam <spamvor...@bad.example.net> wrote:
>> Ben C wrote:
>>> On 2007-07-22, andresm...@aol.com <andresm...@aol.com> wrote:
>>> [...]
>>>> Problem is that the other techies in the group seem to agree with XY's
>>>> theories and not with PQs theories.
>>> If you read between the lines a bit the disagreements between XY and PQ
>>> on how to actually build a wheel are not actually so great.
>> except that i'm not interested in telling people how to build wheels. i
>> /am/ interested in making sure people correctly understand materials
>> theory though,
>>
>>
> You want to teach us material's theory? How do we know that you are
> qualified to teach it? Again, an expert in a field must be able to
> note his claims with credibility, citations past accomplishments, etc.
> Is there anyone else in this group that knows about materials theory
> that can substantiate your claims? Any engineers or physicists here
> that know about materials theory that can agree that JB is talking
> nonesense? Are you the only expert that has figured this out and you
> are misunderstood?
>
> Andres
>
>
did you bother to look up the things i pointed out in "the book"?
thought not.
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Date: 23 Jul 2007 07:38:14
From: andresmuro@aol.com
Subject: Re: spoke tension
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On Jul 23, 7:11 am, jim beam <spamvor...@bad.example.net > wrote:
> andresm...@aol.com wrote:
> > On Jul 22, 7:22 pm, jim beam <spamvor...@bad.example.net> wrote:
> >> andresm...@aol.com wrote:
> >>> On Jul 22, 3:25 pm, jim beam <spamvor...@bad.example.net> wrote:
> >>>> andresm...@aol.com wrote:
> >>>>> On Jul 17, 11:33 pm, jim beam <spamvor...@bad.example.net> wrote:
> >>>>>> jobst.bra...@stanfordalumni.org wrote:
> >>>>>>>http://www.jimbeam.com/beam/default.aspx?writes:
> >>>>>>>>>>> Could someone recommend the proper spoke tension for a rear wheel
> >>>>>>>>>>> built with a Velocity Aerohead OC rim?
> >>>>>>>>>> JB says tension as high as the rim will bear without taking a
> >>>>>>>>>> "taco" or "potato chip" shape; however, jb says tension only as
> >>>>>>>>>> high as the manufacturer's recommendation, or the rim will crack
> >>>>>>>>>> around the spoke hole.
> >>>>>>>>>> LET THE BATTLE BEGIN!
> >>>>>>>>> That's not really what Jobst says. It's what jim beam says Jobst
> >>>>>>>>> says, which are usually two (often very) different things. I guess
> >>>>>>>>> you didn't read the book, either.
> >>>>>>>> "as high as the rim can bear" is what jobst says on this group.
> >>>>>>>> "spokes must be as tight as the rim permits" is what he says in "the
> >>>>>>>> book". [3rd edition.]
> >>>>>>>> either way, he equates increasing spoke tension with increasing
> >>>>>>>> wheel strength: "a wheel with spoke tension near the limit of rim
> >>>>>>>> strength can support large loads easily" - which is untrue,
> >>>>>>>> misleading and reveals gross misunderstanding.
> >>>>>>> I think such statements need a bit of evidence to be credible.
> >>>>>>> A wire spoked bicycle wheel can carry loads up to the point where its
> >>>>>>> spokes become slack from compression as they pass the load point on
> >>>>>>> the road. The looser the spokes the more easily this occurs and
> >>>>>>> conversely the tighter the spoke the less this occurs.
> >>>>>> as discussed on several prior occasions, you are only considering the
> >>>>>> spokes, not the rim. increasing spoke tension increases circumferential
> >>>>>> rim compression. but you miss the point that as the rim's compression
> >>>>>> rises, its load capacity decreases.
> >>>>>> let's assume an aluminum beam has the same tensile strength as it does
> >>>>>> compression. let's say that it yields at [pick a number] +/- 100Mpa.
> >>>>>> in plain bending, the compressive side yields at the same time as the
> >>>>>> tensile side - when this limit is reached. now, compress the beam
> >>>>>> longitudinally at say 50Mpa, i.e. superimpose a stress on it. the
> >>>>>> tensile side of the beam can now support 100 + 50 = 150Mpa before yield.
> >>>>>> but the compressive side can only support 100 - 50 = 50Mpa. so if i
> >>>>>> bend it now, the beam will start to yield supporting only half the load
> >>>>>> it did before.
> >>>>>> with materials with no tensile strength like concrete, you "borrow" from
> >>>>>> the material's [ample] compressive strength to give it pseudo tensile
> >>>>>> strength. but with a material as strong in compression as tension, like
> >>>>>> an aluminum bike rim, that's simply counter-productive.
> >>>>>> in your book, you also argue that rims collapse as soon as spokes go
> >>>>>> slack go slack....http://www.flickr.com/photos/38636024@N00/417157612/
> >>>>>> writing a book is one thing. understanding what to put in it is quite
> >>>>>> another.
> >>>>>>> I have ridden many 100k miles with wheels tensioned as described
> >>>>>>> without needing to re-true them or to replace cracked rims. These
> >>>>>>> have been socketed tubular rims (Fiamme, Super Champion, and Mavic)
> >>>>>>> and Super Champion "Gentleman" and Mavic MA-2 clincher rims. I still
> >>>>>>> ride the latter as do most of my fellow riders, ones who do not see
> >>>>>>> themselves as professional like racers..
> >>>>>>> When riding rough roads such as described in rec.bicycles.rides "Last
> >>>>>>> chance road", I and my bikie friends wonder if the light weight "with
> >>>>>>> it" crowd ever experience roads that are demanding on 36-spoke wheels.
> >>>>>>>http://tinyurl.com/2uc6tb
> >>>>>>> Dings in rims also come from insufficient inflation, a parallel to
> >>>>>>> insufficient spoke tension in supporting loads.
> >>>>>>>http://geocities.com/rayhosler/slideshow.html
> >>>>>>> Ride bike!
> >>>>>> red herring.
> >>>>> This is the dilemma that many people have:
> >>>>> They want advise on wheels and they look for an expert's opinion.
> >>>>> There are two guys who respond. One says: "wheel X with Y
> >>>>> characteristics is ideal." The other one says: "wheel P with Q
> >>>>> characteristics is ideal" both offer contradictory info with some
> >>>>> technical and inaccessible explanations for non engineers.
> >>>>> so, people have to decide which poster to believe. Poster XY has
> >>>>> published a book that is often referred to by bicycle people who
> >>>>> regularly build and sell wheels, shop owners, cyclists, and other
> >>>>> sport aficionados. Poster XY also post pictures in which he rides
> >>>>> with XY wheels in dirt roads, endless hills, tours of Europe, and post
> >>>>> pictures of his friends riding XY wheels with the same
> >>>>> characteristics. Poster XY is a regular consultant for Avocet, and
> >>>>> gets hired to test the products. In other words, poster XY has
> >>>>> established a solid reputation as an expert in the field and can site
> >>>>> a history of expertise and product testing. Moreover, Poster XY
> >>>>> doesn't appear to be affiliated or to receive compensation for many of
> >>>>> the ideas or products that he endorses.
> >>>>> Now, Poster PQ post under a pseudonym. So we don't know if he has ever
> >>>>> published anything. The regular wheel builders in the community and
> >>>>> the shop owners do not seem to endorse him. We don't know if he rides
> >>>>> what he claims to support and has in no established credibility.
> >>>>> It is possible that PQs arguments are all valid. But, for those who
> >>>>> lack expertise to understand the explanations, credibility is
> >>>>> important. It is like reading a research paper with no notes and
> >>>>> references vs one in which all the referred information is noted,
> >>>>> referenced and backed.
> >>>>> When people disagree with poster PQ, he becomes verbally abusive in
> >>>>> frustration.
> >>>>> If poster's PQ arguments were valid, it is very unfortunate. His lack
> >>>>> of credibility prevents his knowledge from being disseminated. Is
> >>>>> there any way that poster PQ can back up his arguments by citing the
> >>>>> millions of wheels that he has built for friends and customers? Can ha
> >>>>> document the millions of miles that he has biked on his wheels? Can
> >>>>> he cite companies that have consulted with him and referred to his
> >>>>> ideas?
> >>>>> I think that poster PQ needs to find a way to document that his ways
> >>>>> have resulted in thousands of wheels being built, thousands of miles
> >>>>> being ridden and a following from other aficionados. If he could build
> >>>>> that kind of reputation, then we could have more interesting
> >>>>> exchanges.
> >>>>> I, myself have built wheels following poster XY with great success. In
> >>>>> fact, being a fatso and a cheapskate, I like XY's ideas, because they
> >>>>> are cost effective and durable and provide many miles of riding. In
> >>>>> fact, my bikes have inexpensive boring looking wheels a la XY. Would I
> >>>>> build wheels following PQ's advise? Not now, based on his current
> >>>>> reputation.
> >>>>> Just my thoughts,
> >>>>> Andres
> >>>> whether or not you like pq's style really isn't the issue. if you don't
> >>>> like it, don't read it. instead, let's look at the, er, "success" of
> >>>> xy's schtick and how it depends on audience.
> >>>> if the audience doesn't know all the technical facts, they rely for
> >>>> judgment on the nature of presentation, appeal to alma mater authority
> >>>> and whether the relatively small proportion of things they /can/ test
> >>>> actually work. in the case of wheel building technique, xy's method
> >>>> does indeed work. "stress relief" as a process "works" in that it
> >>>> builds stable reliable wheels. but /not/ for the reasons stated! now,
> >>>> how would a lay person know the difference? the limit of the typical
> >>>> lay person's ability to follow the arguments presented depends on:
> >>>> 1. presentation style
> >>>> 2. appeal to alma mater authority
> >>>> 3. success in follow wheel build instructions.
> >>>> however, /if/ you're a techie and you want to follow the engineering
> >>>> arguments in xy's book, you find all kinds of problems.
> >>>> there are many, but they include:
> >>>> 1. use of the wrong stress/strain graph to explain spoke deformation.
> >>>> 2. use of the above to construct a "stress relief" theory - which also
> >>>> takes no account of the body of fatigue research accumulated over more
> >>>> than 100 years.
> >>>> 3. misattribution of rim cracking to anodizing based on an inappropriate
> >>>> dye penetrant test.
> >>>> 4. misrepresenting a load calculation to be a strength calculation.
> >>>> 5. neglecting spoke stiffness when attempting to calculate tensiometer
> >>>> deflection.
> >>>> and so on.
> >>>> the point is, under /technical/ scrutiny, there are problems ranging
> >>>> from simple mistakes through to outright fabrication. but how will a
> >>>> lay person know that and therefore be able to judge? instead, again,
> >>>> they're relying on
> >>>> 1. presentation style
> >>>> 2. appeal to alma mater authority
> >>>> 3. success in follow wheel build instructions.
> >>>> and are therefore susceptible to suggestion if the "expert" wants to
> >>>> extrapolate credibility.
> >>>> which leads to examination of the audience. xy has chosen to promote
> >>>> themselves to a carefully selected audience. the success of that is a
> >>>> matter of human nature since the selected target audience has no way of
> >>>> easily determining the truth.
> >>>> as an example, there are regularly cases where individuals impersonate
> >>>> doctors.
> >>>>http://www.signonsandiego.com/uniontrib/20060929/news_7m29raupp.htmlh...
> >>>> these individuals talk the talk, are highly convincing, even hold down
> >>>> jobs, in some cases for years. but in reality, they're frauds. they're
> >>>> very clever people exploiting human gullibility and reliance on "expert"
> >>>> status, but frauds nonetheless.
> >>>> another example would be computer hackers. a true technical "crack" is
> >>>> pretty geeky and hard to achieve. so most break-in's don't occur that
> >>>> way, most system break-in's occur via "social engineering". iow,
> >>>> talking a convincing talk to someone sufficiently gullible that they
> >>>> give away the information necessary to gain system access. and this
> >>>> happens all the time. that's why "phishing" works.
> >>>> bottom line, doctor impersonators don't show up at medical symposiums
> >>>> and try to present research to /real/ experts - they'll be discovered in
> >>>> no time. instead, they
> >>>> ...
> >>>> read more ?
> >>> Problem is that the other techies in the group seem to agree with XY's
> >>> theories and not with PQs theories. In fact, a couple of the techies
> >>> that support XY are often referred to in bicycling magazines work at
> >>> respectable bike shops and are also well known experts. Yet, most of
> >>> the other techies do not agree with PQ.
> >> here's the problem with that argument - none of these "techies" spotted
> >> any of the problems in "the book" before. if they're such reliable
> >> experts, why not?
>
> >>> PQ argues that the other techies are not really techies and don't know
> >>> what they are talking about. But how are the inexperienced suppossed
> >>> to know that PQ is right? And, what is worng with the other techies?
> >>> have they been so brain washed but XY that they cannot differentiate
> >>> good from bad? Well, I would doubt it. some of the techies work on
> >>> wheels using XY's approach and PQ's approach daily. In fact, since
> >>> they are bike shop mechanics, they can actually compare the two
> >>> approaches in their daily work. They end up favoring XY's, because
> >>> they see less failure.
> >> but the wheel build practice is good. that's been said repeatedly. and
> >> it predates the author by at least half a century. it's the proposed
> >> theory that's rubbish. it's based on misunderstanding and underinformed
> >> presumption. you don't have to take any body's word for it - you can
> >> see for yourself. check out the wheel load calcs - no accounting for
> >> wheel strength there. check out the tensiometer math - no accounting
> >> for spoke stiffness there. check out the stress/strain graph cited for
> >> "stress relief" theory, then compare it with the real stress/strain
> >> graphs at the back. real spokes show no strain aging. can't build a
> >> theory using strain aging as a deformation mechanism if it doesn't exist.
>
> >>> In my case, I have have bought bicycles that do not come up with XY's
> >>> equipment. they usually come with the latest most technologically
> >>> advanced stuff that advertisers will claim to offer. As some of the
> >>> equipment fails and I need to repair or replace it, I go with XY's
> >>> suggestions since they are cheaper, easier and more durable.
> >>> The doctor's example is a good one. I have an illness. I look for
> >>> treatment and there are lots of references to Xs treatment. In fact,
> >>> there are pictures of patients of X that have been treated by him and
> >>> seem to be better. X has published a book about his treatment, and is
> >>> often referred to by other doctors as an expert in the field. Other
> >>> doctors prescribe his treatment with success. X works at a well
> >>> established hospital, consults for a respected pharma and yet, he
> >>> doesn't seem to promote a certain brand or looking to make a buck. The
> >>> other doctors that prescribe X's treatment are also well established
> >>> and work for major clinics in the country.
> >>> Another individual "Y" of unknown qualifications claims that while X's
> >>> treatment works it is based in wrong principles, is old fashioned and
> >>> there are better treatments. Although, he cannot find support among
> >>> the other experts about his claims or the alternative treatment that
> >>> he is proposing. When other doctor's challenge Y and tell him that X
> >>> is right on, Y tells the other doctors that they don't know what he is
> >>> talking about. What shall the choice of doctors of the lay person be?
> >>> Of course, there are geniuses in the world that go against the current
> >>> and it turns out that they are right. Maybe, Y and PQ are
> >>> misunderstood geniuses.Who knows. All I can say is what I often tell a
> >>> student that doesnt' like me and wants to plot something against me. I
> >>> usually say that if he doesn't like me, but the rest of the class
> >>> does, the chances of being able to subvert my authority are slim. On
> >>> the other hand, if he can get some allies then, a larger group can
> >>> subvert my authority. I tell the same thing to my employees. If one
> >>> employee has a grievance against another one that everyone seems to
> >>> like and get along with, the chances of people listening to his or her
> >>> grievance are slim. The same applies to knowledge. If someone wants to
> >>> challenge a well established authority, then he needs some support. It
> >>> the challenger cannot get support from experts or demonstrate
> >>> objectively that the new knowledge is better, then he has a slim
> >>> chance of being listened to and a greater one of being labeled a
> >>> wacko. As I said, maybe the challenger is a misunderstood genius.
> >>> However, for a genius to waste his breath and be labeled a wacko for a
> >>> mere bike wheel is hardly worth it to me.
> >> so shut up and let you enjoy having smoke blown up your kilt in peace?
> >> whatever floats your boat dude! but i doubt you'd feel the same if
> >> someone started posting wrong, but pseudo "expert" information on a
> >> subject on which /you/ happened to have detailed and specific knowledge
> >> to the contrary. especially if they were doing it as a means of selling
> >> you something.
>
> > Actually, the subjects that I have expertise in, I can site sources
> > that will back up my knowledge, evidence that something that I propose
> > works, colleagues who have tried using the same techniques with
> > positive results. If someone presented pseudo expert information, and
> > they often do in my field, I can pretty much articulate the reasons
> > for, in my field, XY's arguments are wrong. I can site my own work as
> > well as the work of others to show that something is nonsense. In
> > fact, I have to do this often. I never argue that I am right because I
> > am an expert and therefore I know that the other dude is a "pseudo".
> > If i did that I would be laughed out of my profession. I often have to
> > refer to other established practitioners to back up my contentions.
>
> > With regards to XY vs PQ in wheel building, there seems to be nobody
> > that PQ can refer to except himself who claims that XY is a pseudo
> > expert. IF a pseudo expert in my field presents a theory that all the
> > other experts buy into and I am the only one that disagrees with, then
> > I cease to be the expert. This is referred to as paradigm shift. Once
> > the accepted knowledge in a field is that XY's theories are valid,
> > then XY's theories represent the dominant paradigm in wheelbuilding.
>
> in terms of wheel assembly, they represent industry practice that
> existed from /way/ back. in terms of theory, a lot of it is b.s.
> "dominant paradigm" comes from relentless self-promotion to a selected
> audience that has never bothered to check the math or crack open a
> materials book. [references!] if these theories of "stress relief",
> were presented to a symposium of materials experts, they laugh their
> asses off. etc.
>
> > For the dominant paradigm to shift, PQ will have to cite experts that
> > support PQ's theories.
>
> so what does the ability to successfully assemble a wheel tell you about
> fatigue in non-strain aging materials? what does it tell you about
> pre-stressed structure theory? what does it tell you about tensiometer
> math? the point is, "credibility" in wheel assembly is /NOT/
> credibility in engineering theory! that's the mistake of your argument
I have no idea, but this is not a theoretical engineering discussion
group. I know that theory and practice are related, and there are
engineers that are interested in bicycle wheels and physics forces of
bicycle riding. some are posters in this group. some may be posters or
component developers in other groups. so, are there any engineers,
physicists, mathematicians that support PQ in statying that XY's
engineering claims are nonesense? Are XY and PQ the only two
individuals with expertise in this subject. we know that XY is an
engineer. Is PQ also an engineer?
Andres
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| | |
Date: 23 Jul 2007 20:49:13
From: jim beam
Subject: Re: spoke tension
|
andresmuro@aol.com wrote:
> On Jul 23, 7:11 am, jim beam <spamvor...@bad.example.net> wrote:
>> andresm...@aol.com wrote:
>>> On Jul 22, 7:22 pm, jim beam <spamvor...@bad.example.net> wrote:
>>>> andresm...@aol.com wrote:
>>>>> On Jul 22, 3:25 pm, jim beam <spamvor...@bad.example.net> wrote:
>>>>>> andresm...@aol.com wrote:
>>>>>>> On Jul 17, 11:33 pm, jim beam <spamvor...@bad.example.net> wrote:
>>>>>>>> jobst.bra...@stanfordalumni.org wrote:
>>>>>>>>> http://www.jimbeam.com/beam/default.aspx?writes:
>>>>>>>>>>>>> Could someone recommend the proper spoke tension for a rear wheel
>>>>>>>>>>>>> built with a Velocity Aerohead OC rim?
>>>>>>>>>>>> JB says tension as high as the rim will bear without taking a
>>>>>>>>>>>> "taco" or "potato chip" shape; however, jb says tension only as
>>>>>>>>>>>> high as the manufacturer's recommendation, or the rim will crack
>>>>>>>>>>>> around the spoke hole.
>>>>>>>>>>>> LET THE BATTLE BEGIN!
>>>>>>>>>>> That's not really what Jobst says. It's what jim beam says Jobst
>>>>>>>>>>> says, which are usually two (often very) different things. I guess
>>>>>>>>>>> you didn't read the book, either.
>>>>>>>>>> "as high as the rim can bear" is what jobst says on this group.
>>>>>>>>>> "spokes must be as tight as the rim permits" is what he says in "the
>>>>>>>>>> book". [3rd edition.]
>>>>>>>>>> either way, he equates increasing spoke tension with increasing
>>>>>>>>>> wheel strength: "a wheel with spoke tension near the limit of rim
>>>>>>>>>> strength can support large loads easily" - which is untrue,
>>>>>>>>>> misleading and reveals gross misunderstanding.
>>>>>>>>> I think such statements need a bit of evidence to be credible.
>>>>>>>>> A wire spoked bicycle wheel can carry loads up to the point where its
>>>>>>>>> spokes become slack from compression as they pass the load point on
>>>>>>>>> the road. The looser the spokes the more easily this occurs and
>>>>>>>>> conversely the tighter the spoke the less this occurs.
>>>>>>>> as discussed on several prior occasions, you are only considering the
>>>>>>>> spokes, not the rim. increasing spoke tension increases circumferential
>>>>>>>> rim compression. but you miss the point that as the rim's compression
>>>>>>>> rises, its load capacity decreases.
>>>>>>>> let's assume an aluminum beam has the same tensile strength as it does
>>>>>>>> compression. let's say that it yields at [pick a number] +/- 100Mpa.
>>>>>>>> in plain bending, the compressive side yields at the same time as the
>>>>>>>> tensile side - when this limit is reached. now, compress the beam
>>>>>>>> longitudinally at say 50Mpa, i.e. superimpose a stress on it. the
>>>>>>>> tensile side of the beam can now support 100 + 50 = 150Mpa before yield.
>>>>>>>> but the compressive side can only support 100 - 50 = 50Mpa. so if i
>>>>>>>> bend it now, the beam will start to yield supporting only half the load
>>>>>>>> it did before.
>>>>>>>> with materials with no tensile strength like concrete, you "borrow" from
>>>>>>>> the material's [ample] compressive strength to give it pseudo tensile
>>>>>>>> strength. but with a material as strong in compression as tension, like
>>>>>>>> an aluminum bike rim, that's simply counter-productive.
>>>>>>>> in your book, you also argue that rims collapse as soon as spokes go
>>>>>>>> slack go slack....http://www.flickr.com/photos/38636024@N00/417157612/
>>>>>>>> writing a book is one thing. understanding what to put in it is quite
>>>>>>>> another.
>>>>>>>>> I have ridden many 100k miles with wheels tensioned as described
>>>>>>>>> without needing to re-true them or to replace cracked rims. These
>>>>>>>>> have been socketed tubular rims (Fiamme, Super Champion, and Mavic)
>>>>>>>>> and Super Champion "Gentleman" and Mavic MA-2 clincher rims. I still
>>>>>>>>> ride the latter as do most of my fellow riders, ones who do not see
>>>>>>>>> themselves as professional like racers..
>>>>>>>>> When riding rough roads such as described in rec.bicycles.rides "Last
>>>>>>>>> chance road", I and my bikie friends wonder if the light weight "with
>>>>>>>>> it" crowd ever experience roads that are demanding on 36-spoke wheels.
>>>>>>>>> http://tinyurl.com/2uc6tb
>>>>>>>>> Dings in rims also come from insufficient inflation, a parallel to
>>>>>>>>> insufficient spoke tension in supporting loads.
>>>>>>>>> http://geocities.com/rayhosler/slideshow.html
>>>>>>>>> Ride bike!
>>>>>>>> red herring.
>>>>>>> This is the dilemma that many people have:
>>>>>>> They want advise on wheels and they look for an expert's opinion.
>>>>>>> There are two guys who respond. One says: "wheel X with Y
>>>>>>> characteristics is ideal." The other one says: "wheel P with Q
>>>>>>> characteristics is ideal" both offer contradictory info with some
>>>>>>> technical and inaccessible explanations for non engineers.
>>>>>>> so, people have to decide which poster to believe. Poster XY has
>>>>>>> published a book that is often referred to by bicycle people who
>>>>>>> regularly build and sell wheels, shop owners, cyclists, and other
>>>>>>> sport aficionados. Poster XY also post pictures in which he rides
>>>>>>> with XY wheels in dirt roads, endless hills, tours of Europe, and post
>>>>>>> pictures of his friends riding XY wheels with the same
>>>>>>> characteristics. Poster XY is a regular consultant for Avocet, and
>>>>>>> gets hired to test the products. In other words, poster XY has
>>>>>>> established a solid reputation as an expert in the field and can site
>>>>>>> a history of expertise and product testing. Moreover, Poster XY
>>>>>>> doesn't appear to be affiliated or to receive compensation for many of
>>>>>>> the ideas or products that he endorses.
>>>>>>> Now, Poster PQ post under a pseudonym. So we don't know if he has ever
>>>>>>> published anything. The regular wheel builders in the community and
>>>>>>> the shop owners do not seem to endorse him. We don't know if he rides
>>>>>>> what he claims to support and has in no established credibility.
>>>>>>> It is possible that PQs arguments are all valid. But, for those who
>>>>>>> lack expertise to understand the explanations, credibility is
>>>>>>> important. It is like reading a research paper with no notes and
>>>>>>> references vs one in which all the referred information is noted,
>>>>>>> referenced and backed.
>>>>>>> When people disagree with poster PQ, he becomes verbally abusive in
>>>>>>> frustration.
>>>>>>> If poster's PQ arguments were valid, it is very unfortunate. His lack
>>>>>>> of credibility prevents his knowledge from being disseminated. Is
>>>>>>> there any way that poster PQ can back up his arguments by citing the
>>>>>>> millions of wheels that he has built for friends and customers? Can ha
>>>>>>> document the millions of miles that he has biked on his wheels? Can
>>>>>>> he cite companies that have consulted with him and referred to his
>>>>>>> ideas?
>>>>>>> I think that poster PQ needs to find a way to document that his ways
>>>>>>> have resulted in thousands of wheels being built, thousands of miles
>>>>>>> being ridden and a following from other aficionados. If he could build
>>>>>>> that kind of reputation, then we could have more interesting
>>>>>>> exchanges.
>>>>>>> I, myself have built wheels following poster XY with great success. In
>>>>>>> fact, being a fatso and a cheapskate, I like XY's ideas, because they
>>>>>>> are cost effective and durable and provide many miles of riding. In
>>>>>>> fact, my bikes have inexpensive boring looking wheels a la XY. Would I
>>>>>>> build wheels following PQ's advise? Not now, based on his current
>>>>>>> reputation.
>>>>>>> Just my thoughts,
>>>>>>> Andres
>>>>>> whether or not you like pq's style really isn't the issue. if you don't
>>>>>> like it, don't read it. instead, let's look at the, er, "success" of
>>>>>> xy's schtick and how it depends on audience.
>>>>>> if the audience doesn't know all the technical facts, they rely for
>>>>>> judgment on the nature of presentation, appeal to alma mater authority
>>>>>> and whether the relatively small proportion of things they /can/ test
>>>>>> actually work. in the case of wheel building technique, xy's method
>>>>>> does indeed work. "stress relief" as a process "works" in that it
>>>>>> builds stable reliable wheels. but /not/ for the reasons stated! now,
>>>>>> how would a lay person know the difference? the limit of the typical
>>>>>> lay person's ability to follow the arguments presented depends on:
>>>>>> 1. presentation style
>>>>>> 2. appeal to alma mater authority
>>>>>> 3. success in follow wheel build instructions.
>>>>>> however, /if/ you're a techie and you want to follow the engineering
>>>>>> arguments in xy's book, you find all kinds of problems.
>>>>>> there are many, but they include:
>>>>>> 1. use of the wrong stress/strain graph to explain spoke deformation.
>>>>>> 2. use of the above to construct a "stress relief" theory - which also
>>>>>> takes no account of the body of fatigue research accumulated over more
>>>>>> than 100 years.
>>>>>> 3. misattribution of rim cracking to anodizing based on an inappropriate
>>>>>> dye penetrant test.
>>>>>> 4. misrepresenting a load calculation to be a strength calculation.
>>>>>> 5. neglecting spoke stiffness when attempting to calculate tensiometer
>>>>>> deflection.
>>>>>> and so on.
>>>>>> the point is, under /technical/ scrutiny, there are problems ranging
>>>>>> from simple mistakes through to outright fabrication. but how will a
>>>>>> lay person know that and therefore be able to judge? instead, again,
>>>>>> they're relying on
>>>>>> 1. presentation style
>>>>>> 2. appeal to alma mater authority
>>>>>> 3. success in follow wheel build instructions.
>>>>>> and are therefore susceptible to suggestion if the "expert" wants to
>>>>>> extrapolate credibility.
>>>>>> which leads to examination of the audience. xy has chosen to promote
>>>>>> themselves to a carefully selected audience. the success of that is a
>>>>>> matter of human nature since the selected target audience has no way of
>>>>>> easily determining the truth.
>>>>>> as an example, there are regularly cases where individuals impersonate
>>>>>> doctors.
>>>>>> http://www.signonsandiego.com/uniontrib/20060929/news_7m29raupp.htmlh...
>>>>>> these individuals talk the talk, are highly convincing, even hold down
>>>>>> jobs, in some cases for years. but in reality, they're frauds. they're
>>>>>> very clever people exploiting human gullibility and reliance on "expert"
>>>>>> status, but frauds nonetheless.
>>>>>> another example would be computer hackers. a true technical "crack" is
>>>>>> pretty geeky and hard to achieve. so most break-in's don't occur that
>>>>>> way, most system break-in's occur via "social engineering". iow,
>>>>>> talking a convincing talk to someone sufficiently gullible that they
>>>>>> give away the information necessary to gain system access. and this
>>>>>> happens all the time. that's why "phishing" works.
>>>>>> bottom line, doctor impersonators don't show up at medical symposiums
>>>>>> and try to present research to /real/ experts - they'll be discovered in
>>>>>> no time. instead, they
>>>>>> ...
>>>>>> read more ?
>>>>> Problem is that the other techies in the group seem to agree with XY's
>>>>> theories and not with PQs theories. In fact, a couple of the techies
>>>>> that support XY are often referred to in bicycling magazines work at
>>>>> respectable bike shops and are also well known experts. Yet, most of
>>>>> the other techies do not agree with PQ.
>>>> here's the problem with that argument - none of these "techies" spotted
>>>> any of the problems in "the book" before. if they're such reliable
>>>> experts, why not?
>>>>> PQ argues that the other techies are not really techies and don't know
>>>>> what they are talking about. But how are the inexperienced suppossed
>>>>> to know that PQ is right? And, what is worng with the other techies?
>>>>> have they been so brain washed but XY that they cannot differentiate
>>>>> good from bad? Well, I would doubt it. some of the techies work on
>>>>> wheels using XY's approach and PQ's approach daily. In fact, since
>>>>> they are bike shop mechanics, they can actually compare the two
>>>>> approaches in their daily work. They end up favoring XY's, because
>>>>> they see less failure.
>>>> but the wheel build practice is good. that's been said repeatedly. and
>>>> it predates the author by at least half a century. it's the proposed
>>>> theory that's rubbish. it's based on misunderstanding and underinformed
>>>> presumption. you don't have to take any body's word for it - you can
>>>> see for yourself. check out the wheel load calcs - no accounting for
>>>> wheel strength there. check out the tensiometer math - no accounting
>>>> for spoke stiffness there. check out the stress/strain graph cited for
>>>> "stress relief" theory, then compare it with the real stress/strain
>>>> graphs at the back. real spokes show no strain aging. can't build a
>>>> theory using strain aging as a deformation mechanism if it doesn't exist.
>>>>> In my case, I have have bought bicycles that do not come up with XY's
>>>>> equipment. they usually come with the latest most technologically
>>>>> advanced stuff that advertisers will claim to offer. As some of the
>>>>> equipment fails and I need to repair or replace it, I go with XY's
>>>>> suggestions since they are cheaper, easier and more durable.
>>>>> The doctor's example is a good one. I have an illness. I look for
>>>>> treatment and there are lots of references to Xs treatment. In fact,
>>>>> there are pictures of patients of X that have been treated by him and
>>>>> seem to be better. X has published a book about his treatment, and is
>>>>> often referred to by other doctors as an expert in the field. Other
>>>>> doctors prescribe his treatment with success. X works at a well
>>>>> established hospital, consults for a respected pharma and yet, he
>>>>> doesn't seem to promote a certain brand or looking to make a buck. The
>>>>> other doctors that prescribe X's treatment are also well established
>>>>> and work for major clinics in the country.
>>>>> Another individual "Y" of unknown qualifications claims that while X's
>>>>> treatment works it is based in wrong principles, is old fashioned and
>>>>> there are better treatments. Although, he cannot find support among
>>>>> the other experts about his claims or the alternative treatment that
>>>>> he is proposing. When other doctor's challenge Y and tell him that X
>>>>> is right on, Y tells the other doctors that they don't know what he is
>>>>> talking about. What shall the choice of doctors of the lay person be?
>>>>> Of course, there are geniuses in the world that go against the current
>>>>> and it turns out that they are right. Maybe, Y and PQ are
>>>>> misunderstood geniuses.Who knows. All I can say is what I often tell a
>>>>> student that doesnt' like me and wants to plot something against me. I
>>>>> usually say that if he doesn't like me, but the rest of the class
>>>>> does, the chances of being able to subvert my authority are slim. On
>>>>> the other hand, if he can get some allies then, a larger group can
>>>>> subvert my authority. I tell the same thing to my employees. If one
>>>>> employee has a grievance against another one that everyone seems to
>>>>> like and get along with, the chances of people listening to his or her
>>>>> grievance are slim. The same applies to knowledge. If someone wants to
>>>>> challenge a well established authority, then he needs some support. It
>>>>> the challenger cannot get support from experts or demonstrate
>>>>> objectively that the new knowledge is better, then he has a slim
>>>>> chance of being listened to and a greater one of being labeled a
>>>>> wacko. As I said, maybe the challenger is a misunderstood genius.
>>>>> However, for a genius to waste his breath and be labeled a wacko for a
>>>>> mere bike wheel is hardly worth it to me.
>>>> so shut up and let you enjoy having smoke blown up your kilt in peace?
>>>> whatever floats your boat dude! but i doubt you'd feel the same if
>>>> someone started posting wrong, but pseudo "expert" information on a
>>>> subject on which /you/ happened to have detailed and specific knowledge
>>>> to the contrary. especially if they were doing it as a means of selling
>>>> you something.
>>> Actually, the subjects that I have expertise in, I can site sources
>>> that will back up my knowledge, evidence that something that I propose
>>> works, colleagues who have tried using the same techniques with
>>> positive results. If someone presented pseudo expert information, and
>>> they often do in my field, I can pretty much articulate the reasons
>>> for, in my field, XY's arguments are wrong. I can site my own work as
>>> well as the work of others to show that something is nonsense. In
>>> fact, I have to do this often. I never argue that I am right because I
>>> am an expert and therefore I know that the other dude is a "pseudo".
>>> If i did that I would be laughed out of my profession. I often have to
>>> refer to other established practitioners to back up my contentions.
>>> With regards to XY vs PQ in wheel building, there seems to be nobody
>>> that PQ can refer to except himself who claims that XY is a pseudo
>>> expert. IF a pseudo expert in my field presents a theory that all the
>>> other experts buy into and I am the only one that disagrees with, then
>>> I cease to be the expert. This is referred to as paradigm shift. Once
>>> the accepted knowledge in a field is that XY's theories are valid,
>>> then XY's theories represent the dominant paradigm in wheelbuilding.
>> in terms of wheel assembly, they represent industry practice that
>> existed from /way/ back. in terms of theory, a lot of it is b.s.
>> "dominant paradigm" comes from relentless self-promotion to a selected
>> audience that has never bothered to check the math or crack open a
>> materials book. [references!] if these theories of "stress relief",
>> were presented to a symposium of materials experts, they laugh their
>> asses off. etc.
>>
>>> For the dominant paradigm to shift, PQ will have to cite experts that
>>> support PQ's theories.
>> so what does the ability to successfully assemble a wheel tell you about
>> fatigue in non-strain aging materials? what does it tell you about
>> pre-stressed structure theory? what does it tell you about tensiometer
>> math? the point is, "credibility" in wheel assembly is /NOT/
>> credibility in engineering theory! that's the mistake of your argument
>
> I have no idea, but this is not a theoretical engineering discussion
> group.
sorry, i must have been mistaken. when i saw "tech" in the group
address, i wrongly assumed the intent was not for idle freakin' chit
chat, politics and b.s. masquerading as "expertise".
> I know that theory and practice are related, and there are
> engineers that are interested in bicycle wheels and physics forces of
> bicycle riding. some are posters in this group. some may be posters or
> component developers in other groups. so, are there any engineers,
> physicists, mathematicians that support PQ in statying that XY's
> engineering claims are nonesense?
i ask again, where are these experts that have spotted and discussed the
mistakes in "the book"? unless you're denying the mistakes of course.
> Are XY and PQ the only two
> individuals with expertise in this subject. we know that XY is an
> engineer. Is PQ also an engineer?
>
no, he's a materials guy. you know, one of those sad pathetic
individuals doomed to suffer the constant disappointment of having to
mop up after the so-called "engineers" who never bother to attend
materials lectures because there weren't enough credits to make it worth
their while, and material's just material so who cares how the stuff
actually works anyway. oh, the widget broke? must be the material.
couldn't possibly be the wonderful perfect design. no siree bob.
because engineers know all about this stuff. and engineers actually
/did/ attend materials lectures. even when they didn't.
|
| |
Date: 22 Jul 2007 22:24:37
From: andresmuro@aol.com
Subject: Re: spoke tension
|
On Jul 22, 7:22 pm, jim beam <spamvor...@bad.example.net > wrote:
> andresm...@aol.com wrote:
> > On Jul 22, 3:25 pm, jim beam <spamvor...@bad.example.net> wrote:
> >> andresm...@aol.com wrote:
> >>> On Jul 17, 11:33 pm, jim beam <spamvor...@bad.example.net> wrote:
> >>>> jobst.bra...@stanfordalumni.org wrote:
> >>>>>http://www.jimbeam.com/beam/default.aspx?writes:
> >>>>>>>>> Could someone recommend the proper spoke tension for a rear wheel
> >>>>>>>>> built with a Velocity Aerohead OC rim?
> >>>>>>>> JB says tension as high as the rim will bear without taking a
> >>>>>>>> "taco" or "potato chip" shape; however, jb says tension only as
> >>>>>>>> high as the manufacturer's recommendation, or the rim will crack
> >>>>>>>> around the spoke hole.
> >>>>>>>> LET THE BATTLE BEGIN!
> >>>>>>> That's not really what Jobst says. It's what jim beam says Jobst
> >>>>>>> says, which are usually two (often very) different things. I guess
> >>>>>>> you didn't read the book, either.
> >>>>>> "as high as the rim can bear" is what jobst says on this group.
> >>>>>> "spokes must be as tight as the rim permits" is what he says in "the
> >>>>>> book". [3rd edition.]
> >>>>>> either way, he equates increasing spoke tension with increasing
> >>>>>> wheel strength: "a wheel with spoke tension near the limit of rim
> >>>>>> strength can support large loads easily" - which is untrue,
> >>>>>> misleading and reveals gross misunderstanding.
> >>>>> I think such statements need a bit of evidence to be credible.
> >>>>> A wire spoked bicycle wheel can carry loads up to the point where its
> >>>>> spokes become slack from compression as they pass the load point on
> >>>>> the road. The looser the spokes the more easily this occurs and
> >>>>> conversely the tighter the spoke the less this occurs.
> >>>> as discussed on several prior occasions, you are only considering the
> >>>> spokes, not the rim. increasing spoke tension increases circumferential
> >>>> rim compression. but you miss the point that as the rim's compression
> >>>> rises, its load capacity decreases.
> >>>> let's assume an aluminum beam has the same tensile strength as it does
> >>>> compression. let's say that it yields at [pick a number] +/- 100Mpa.
> >>>> in plain bending, the compressive side yields at the same time as the
> >>>> tensile side - when this limit is reached. now, compress the beam
> >>>> longitudinally at say 50Mpa, i.e. superimpose a stress on it. the
> >>>> tensile side of the beam can now support 100 + 50 = 150Mpa before yield.
> >>>> but the compressive side can only support 100 - 50 = 50Mpa. so if i
> >>>> bend it now, the beam will start to yield supporting only half the load
> >>>> it did before.
> >>>> with materials with no tensile strength like concrete, you "borrow" from
> >>>> the material's [ample] compressive strength to give it pseudo tensile
> >>>> strength. but with a material as strong in compression as tension, like
> >>>> an aluminum bike rim, that's simply counter-productive.
> >>>> in your book, you also argue that rims collapse as soon as spokes go
> >>>> slack go slack....http://www.flickr.com/photos/38636024@N00/417157612/
> >>>> writing a book is one thing. understanding what to put in it is quite
> >>>> another.
> >>>>> I have ridden many 100k miles with wheels tensioned as described
> >>>>> without needing to re-true them or to replace cracked rims. These
> >>>>> have been socketed tubular rims (Fiamme, Super Champion, and Mavic)
> >>>>> and Super Champion "Gentleman" and Mavic MA-2 clincher rims. I still
> >>>>> ride the latter as do most of my fellow riders, ones who do not see
> >>>>> themselves as professional like racers..
> >>>>> When riding rough roads such as described in rec.bicycles.rides "Last
> >>>>> chance road", I and my bikie friends wonder if the light weight "with
> >>>>> it" crowd ever experience roads that are demanding on 36-spoke wheels.
> >>>>>http://tinyurl.com/2uc6tb
> >>>>> Dings in rims also come from insufficient inflation, a parallel to
> >>>>> insufficient spoke tension in supporting loads.
> >>>>>http://geocities.com/rayhosler/slideshow.html
> >>>>> Ride bike!
> >>>> red herring.
> >>> This is the dilemma that many people have:
> >>> They want advise on wheels and they look for an expert's opinion.
> >>> There are two guys who respond. One says: "wheel X with Y
> >>> characteristics is ideal." The other one says: "wheel P with Q
> >>> characteristics is ideal" both offer contradictory info with some
> >>> technical and inaccessible explanations for non engineers.
> >>> so, people have to decide which poster to believe. Poster XY has
> >>> published a book that is often referred to by bicycle people who
> >>> regularly build and sell wheels, shop owners, cyclists, and other
> >>> sport aficionados. Poster XY also post pictures in which he rides
> >>> with XY wheels in dirt roads, endless hills, tours of Europe, and post
> >>> pictures of his friends riding XY wheels with the same
> >>> characteristics. Poster XY is a regular consultant for Avocet, and
> >>> gets hired to test the products. In other words, poster XY has
> >>> established a solid reputation as an expert in the field and can site
> >>> a history of expertise and product testing. Moreover, Poster XY
> >>> doesn't appear to be affiliated or to receive compensation for many of
> >>> the ideas or products that he endorses.
> >>> Now, Poster PQ post under a pseudonym. So we don't know if he has ever
> >>> published anything. The regular wheel builders in the community and
> >>> the shop owners do not seem to endorse him. We don't know if he rides
> >>> what he claims to support and has in no established credibility.
> >>> It is possible that PQs arguments are all valid. But, for those who
> >>> lack expertise to understand the explanations, credibility is
> >>> important. It is like reading a research paper with no notes and
> >>> references vs one in which all the referred information is noted,
> >>> referenced and backed.
> >>> When people disagree with poster PQ, he becomes verbally abusive in
> >>> frustration.
> >>> If poster's PQ arguments were valid, it is very unfortunate. His lack
> >>> of credibility prevents his knowledge from being disseminated. Is
> >>> there any way that poster PQ can back up his arguments by citing the
> >>> millions of wheels that he has built for friends and customers? Can ha
> >>> document the millions of miles that he has biked on his wheels? Can
> >>> he cite companies that have consulted with him and referred to his
> >>> ideas?
> >>> I think that poster PQ needs to find a way to document that his ways
> >>> have resulted in thousands of wheels being built, thousands of miles
> >>> being ridden and a following from other aficionados. If he could build
> >>> that kind of reputation, then we could have more interesting
> >>> exchanges.
> >>> I, myself have built wheels following poster XY with great success. In
> >>> fact, being a fatso and a cheapskate, I like XY's ideas, because they
> >>> are cost effective and durable and provide many miles of riding. In
> >>> fact, my bikes have inexpensive boring looking wheels a la XY. Would I
> >>> build wheels following PQ's advise? Not now, based on his current
> >>> reputation.
> >>> Just my thoughts,
> >>> Andres
> >> whether or not you like pq's style really isn't the issue. if you don't
> >> like it, don't read it. instead, let's look at the, er, "success" of
> >> xy's schtick and how it depends on audience.
>
> >> if the audience doesn't know all the technical facts, they rely for
> >> judgment on the nature of presentation, appeal to alma mater authority
> >> and whether the relatively small proportion of things they /can/ test
> >> actually work. in the case of wheel building technique, xy's method
> >> does indeed work. "stress relief" as a process "works" in that it
> >> builds stable reliable wheels. but /not/ for the reasons stated! now,
> >> how would a lay person know the difference? the limit of the typical
> >> lay person's ability to follow the arguments presented depends on:
>
> >> 1. presentation style
> >> 2. appeal to alma mater authority
> >> 3. success in follow wheel build instructions.
>
> >> however, /if/ you're a techie and you want to follow the engineering
> >> arguments in xy's book, you find all kinds of problems.
>
> >> there are many, but they include:
> >> 1. use of the wrong stress/strain graph to explain spoke deformation.
> >> 2. use of the above to construct a "stress relief" theory - which also
> >> takes no account of the body of fatigue research accumulated over more
> >> than 100 years.
> >> 3. misattribution of rim cracking to anodizing based on an inappropriate
> >> dye penetrant test.
> >> 4. misrepresenting a load calculation to be a strength calculation.
> >> 5. neglecting spoke stiffness when attempting to calculate tensiometer
> >> deflection.
>
> >> and so on.
>
> >> the point is, under /technical/ scrutiny, there are problems ranging
> >> from simple mistakes through to outright fabrication. but how will a
> >> lay person know that and therefore be able to judge? instead, again,
> >> they're relying on
>
> >> 1. presentation style
> >> 2. appeal to alma mater authority
> >> 3. success in follow wheel build instructions.
>
> >> and are therefore susceptible to suggestion if the "expert" wants to
> >> extrapolate credibility.
>
> >> which leads to examination of the audience. xy has chosen to promote
> >> themselves to a carefully selected audience. the success of that is a
> >> matter of human nature since the selected target audience has no way of
> >> easily determining the truth.
>
> >> as an example, there are regularly cases where individuals impersonate
> >> doctors.
>
> >>http://www.signonsandiego.com/uniontrib/20060929/news_7m29raupp.htmlh...
>
> >> these individuals talk the talk, are highly convincing, even hold down
> >> jobs, in some cases for years. but in reality, they're frauds. they're
> >> very clever people exploiting human gullibility and reliance on "expert"
> >> status, but frauds nonetheless.
>
> >> another example would be computer hackers. a true technical "crack" is
> >> pretty geeky and hard to achieve. so most break-in's don't occur that
> >> way, most system break-in's occur via "social engineering". iow,
> >> talking a convincing talk to someone sufficiently gullible that they
> >> give away the information necessary to gain system access. and this
> >> happens all the time. that's why "phishing" works.
>
> >> bottom line, doctor impersonators don't show up at medical symposiums
> >> and try to present research to /real/ experts - they'll be discovered in
> >> no time. instead, they
> >> ...
>
> >> read more ?
>
> > Problem is that the other techies in the group seem to agree with XY's
> > theories and not with PQs theories. In fact, a couple of the techies
> > that support XY are often referred to in bicycling magazines work at
> > respectable bike shops and are also well known experts. Yet, most of
> > the other techies do not agree with PQ.
>
> here's the problem with that argument - none of these "techies" spotted
> any of the problems in "the book" before. if they're such reliable
> experts, why not?
>
>
>
> > PQ argues that the other techies are not really techies and don't know
> > what they are talking about. But how are the inexperienced suppossed
> > to know that PQ is right? And, what is worng with the other techies?
> > have they been so brain washed but XY that they cannot differentiate
> > good from bad? Well, I would doubt it. some of the techies work on
> > wheels using XY's approach and PQ's approach daily. In fact, since
> > they are bike shop mechanics, they can actually compare the two
> > approaches in their daily work. They end up favoring XY's, because
> > they see less failure.
>
> but the wheel build practice is good. that's been said repeatedly. and
> it predates the author by at least half a century. it's the proposed
> theory that's rubbish. it's based on misunderstanding and underinformed
> presumption. you don't have to take any body's word for it - you can
> see for yourself. check out the wheel load calcs - no accounting for
> wheel strength there. check out the tensiometer math - no accounting
> for spoke stiffness there. check out the stress/strain graph cited for
> "stress relief" theory, then compare it with the real stress/strain
> graphs at the back. real spokes show no strain aging. can't build a
> theory using strain aging as a deformation mechanism if it doesn't exist.
>
>
>
> > In my case, I have have bought bicycles that do not come up with XY's
> > equipment. they usually come with the latest most technologically
> > advanced stuff that advertisers will claim to offer. As some of the
> > equipment fails and I need to repair or replace it, I go with XY's
> > suggestions since they are cheaper, easier and more durable.
>
> > The doctor's example is a good one. I have an illness. I look for
> > treatment and there are lots of references to Xs treatment. In fact,
> > there are pictures of patients of X that have been treated by him and
> > seem to be better. X has published a book about his treatment, and is
> > often referred to by other doctors as an expert in the field. Other
> > doctors prescribe his treatment with success. X works at a well
> > established hospital, consults for a respected pharma and yet, he
> > doesn't seem to promote a certain brand or looking to make a buck. The
> > other doctors that prescribe X's treatment are also well established
> > and work for major clinics in the country.
>
> > Another individual "Y" of unknown qualifications claims that while X's
> > treatment works it is based in wrong principles, is old fashioned and
> > there are better treatments. Although, he cannot find support among
> > the other experts about his claims or the alternative treatment that
> > he is proposing. When other doctor's challenge Y and tell him that X
> > is right on, Y tells the other doctors that they don't know what he is
> > talking about. What shall the choice of doctors of the lay person be?
>
> > Of course, there are geniuses in the world that go against the current
> > and it turns out that they are right. Maybe, Y and PQ are
> > misunderstood geniuses.Who knows. All I can say is what I often tell a
> > student that doesnt' like me and wants to plot something against me. I
> > usually say that if he doesn't like me, but the rest of the class
> > does, the chances of being able to subvert my authority are slim. On
> > the other hand, if he can get some allies then, a larger group can
> > subvert my authority. I tell the same thing to my employees. If one
> > employee has a grievance against another one that everyone seems to
> > like and get along with, the chances of people listening to his or her
> > grievance are slim. The same applies to knowledge. If someone wants to
> > challenge a well established authority, then he needs some support. It
> > the challenger cannot get support from experts or demonstrate
> > objectively that the new knowledge is better, then he has a slim
> > chance of being listened to and a greater one of being labeled a
> > wacko. As I said, maybe the challenger is a misunderstood genius.
> > However, for a genius to waste his breath and be labeled a wacko for a
> > mere bike wheel is hardly worth it to me.
>
> so shut up and let you enjoy having smoke blown up your kilt in peace?
> whatever floats your boat dude! but i doubt you'd feel the same if
> someone started posting wrong, but pseudo "expert" information on a
> subject on which /you/ happened to have detailed and specific knowledge
> to the contrary. especially if they were doing it as a means of selling
> you something.
Actually, the subjects that I have expertise in, I can site sources
that will back up my knowledge, evidence that something that I propose
works, colleagues who have tried using the same techniques with
positive results. If someone presented pseudo expert information, and
they often do in my field, I can pretty much articulate the reasons
for, in my field, XY's arguments are wrong. I can site my own work as
well as the work of others to show that something is nonsense. In
fact, I have to do this often. I never argue that I am right because I
am an expert and therefore I know that the other dude is a "pseudo".
If i did that I would be laughed out of my profession. I often have to
refer to other established practitioners to back up my contentions.
With regards to XY vs PQ in wheel building, there seems to be nobody
that PQ can refer to except himself who claims that XY is a pseudo
expert. IF a pseudo expert in my field presents a theory that all the
other experts buy into and I am the only one that disagrees with, then
I cease to be the expert. This is referred to as paradigm shift. Once
the accepted knowledge in a field is that XY's theories are valid,
then XY's theories represent the dominant paradigm in wheelbuilding.
For the dominant paradigm to shift, PQ will have to cite experts that
support PQ's theories.
Andres
|
| | |
Date: 23 Jul 2007 06:11:16
From: jim beam
Subject: Re: spoke tension
|
andresmuro@aol.com wrote:
> On Jul 22, 7:22 pm, jim beam <spamvor...@bad.example.net> wrote:
>> andresm...@aol.com wrote:
>>> On Jul 22, 3:25 pm, jim beam <spamvor...@bad.example.net> wrote:
>>>> andresm...@aol.com wrote:
>>>>> On Jul 17, 11:33 pm, jim beam <spamvor...@bad.example.net> wrote:
>>>>>> jobst.bra...@stanfordalumni.org wrote:
>>>>>>> http://www.jimbeam.com/beam/default.aspx?writes:
>>>>>>>>>>> Could someone recommend the proper spoke tension for a rear wheel
>>>>>>>>>>> built with a Velocity Aerohead OC rim?
>>>>>>>>>> JB says tension as high as the rim will bear without taking a
>>>>>>>>>> "taco" or "potato chip" shape; however, jb says tension only as
>>>>>>>>>> high as the manufacturer's recommendation, or the rim will crack
>>>>>>>>>> around the spoke hole.
>>>>>>>>>> LET THE BATTLE BEGIN!
>>>>>>>>> That's not really what Jobst says. It's what jim beam says Jobst
>>>>>>>>> says, which are usually two (often very) different things. I guess
>>>>>>>>> you didn't read the book, either.
>>>>>>>> "as high as the rim can bear" is what jobst says on this group.
>>>>>>>> "spokes must be as tight as the rim permits" is what he says in "the
>>>>>>>> book". [3rd edition.]
>>>>>>>> either way, he equates increasing spoke tension with increasing
>>>>>>>> wheel strength: "a wheel with spoke tension near the limit of rim
>>>>>>>> strength can support large loads easily" - which is untrue,
>>>>>>>> misleading and reveals gross misunderstanding.
>>>>>>> I think such statements need a bit of evidence to be credible.
>>>>>>> A wire spoked bicycle wheel can carry loads up to the point where its
>>>>>>> spokes become slack from compression as they pass the load point on
>>>>>>> the road. The looser the spokes the more easily this occurs and
>>>>>>> conversely the tighter the spoke the less this occurs.
>>>>>> as discussed on several prior occasions, you are only considering the
>>>>>> spokes, not the rim. increasing spoke tension increases circumferential
>>>>>> rim compression. but you miss the point that as the rim's compression
>>>>>> rises, its load capacity decreases.
>>>>>> let's assume an aluminum beam has the same tensile strength as it does
>>>>>> compression. let's say that it yields at [pick a number] +/- 100Mpa.
>>>>>> in plain bending, the compressive side yields at the same time as the
>>>>>> tensile side - when this limit is reached. now, compress the beam
>>>>>> longitudinally at say 50Mpa, i.e. superimpose a stress on it. the
>>>>>> tensile side of the beam can now support 100 + 50 = 150Mpa before yield.
>>>>>> but the compressive side can only support 100 - 50 = 50Mpa. so if i
>>>>>> bend it now, the beam will start to yield supporting only half the load
>>>>>> it did before.
>>>>>> with materials with no tensile strength like concrete, you "borrow" from
>>>>>> the material's [ample] compressive strength to give it pseudo tensile
>>>>>> strength. but with a material as strong in compression as tension, like
>>>>>> an aluminum bike rim, that's simply counter-productive.
>>>>>> in your book, you also argue that rims collapse as soon as spokes go
>>>>>> slack go slack....http://www.flickr.com/photos/38636024@N00/417157612/
>>>>>> writing a book is one thing. understanding what to put in it is quite
>>>>>> another.
>>>>>>> I have ridden many 100k miles with wheels tensioned as described
>>>>>>> without needing to re-true them or to replace cracked rims. These
>>>>>>> have been socketed tubular rims (Fiamme, Super Champion, and Mavic)
>>>>>>> and Super Champion "Gentleman" and Mavic MA-2 clincher rims. I still
>>>>>>> ride the latter as do most of my fellow riders, ones who do not see
>>>>>>> themselves as professional like racers..
>>>>>>> When riding rough roads such as described in rec.bicycles.rides "Last
>>>>>>> chance road", I and my bikie friends wonder if the light weight "with
>>>>>>> it" crowd ever experience roads that are demanding on 36-spoke wheels.
>>>>>>> http://tinyurl.com/2uc6tb
>>>>>>> Dings in rims also come from insufficient inflation, a parallel to
>>>>>>> insufficient spoke tension in supporting loads.
>>>>>>> http://geocities.com/rayhosler/slideshow.html
>>>>>>> Ride bike!
>>>>>> red herring.
>>>>> This is the dilemma that many people have:
>>>>> They want advise on wheels and they look for an expert's opinion.
>>>>> There are two guys who respond. One says: "wheel X with Y
>>>>> characteristics is ideal." The other one says: "wheel P with Q
>>>>> characteristics is ideal" both offer contradictory info with some
>>>>> technical and inaccessible explanations for non engineers.
>>>>> so, people have to decide which poster to believe. Poster XY has
>>>>> published a book that is often referred to by bicycle people who
>>>>> regularly build and sell wheels, shop owners, cyclists, and other
>>>>> sport aficionados. Poster XY also post pictures in which he rides
>>>>> with XY wheels in dirt roads, endless hills, tours of Europe, and post
>>>>> pictures of his friends riding XY wheels with the same
>>>>> characteristics. Poster XY is a regular consultant for Avocet, and
>>>>> gets hired to test the products. In other words, poster XY has
>>>>> established a solid reputation as an expert in the field and can site
>>>>> a history of expertise and product testing. Moreover, Poster XY
>>>>> doesn't appear to be affiliated or to receive compensation for many of
>>>>> the ideas or products that he endorses.
>>>>> Now, Poster PQ post under a pseudonym. So we don't know if he has ever
>>>>> published anything. The regular wheel builders in the community and
>>>>> the shop owners do not seem to endorse him. We don't know if he rides
>>>>> what he claims to support and has in no established credibility.
>>>>> It is possible that PQs arguments are all valid. But, for those who
>>>>> lack expertise to understand the explanations, credibility is
>>>>> important. It is like reading a research paper with no notes and
>>>>> references vs one in which all the referred information is noted,
>>>>> referenced and backed.
>>>>> When people disagree with poster PQ, he becomes verbally abusive in
>>>>> frustration.
>>>>> If poster's PQ arguments were valid, it is very unfortunate. His lack
>>>>> of credibility prevents his knowledge from being disseminated. Is
>>>>> there any way that poster PQ can back up his arguments by citing the
>>>>> millions of wheels that he has built for friends and customers? Can ha
>>>>> document the millions of miles that he has biked on his wheels? Can
>>>>> he cite companies that have consulted with him and referred to his
>>>>> ideas?
>>>>> I think that poster PQ needs to find a way to document that his ways
>>>>> have resulted in thousands of wheels being built, thousands of miles
>>>>> being ridden and a following from other aficionados. If he could build
>>>>> that kind of reputation, then we could have more interesting
>>>>> exchanges.
>>>>> I, myself have built wheels following poster XY with great success. In
>>>>> fact, being a fatso and a cheapskate, I like XY's ideas, because they
>>>>> are cost effective and durable and provide many miles of riding. In
>>>>> fact, my bikes have inexpensive boring looking wheels a la XY. Would I
>>>>> build wheels following PQ's advise? Not now, based on his current
>>>>> reputation.
>>>>> Just my thoughts,
>>>>> Andres
>>>> whether or not you like pq's style really isn't the issue. if you don't
>>>> like it, don't read it. instead, let's look at the, er, "success" of
>>>> xy's schtick and how it depends on audience.
>>>> if the audience doesn't know all the technical facts, they rely for
>>>> judgment on the nature of presentation, appeal to alma mater authority
>>>> and whether the relatively small proportion of things they /can/ test
>>>> actually work. in the case of wheel building technique, xy's method
>>>> does indeed work. "stress relief" as a process "works" in that it
>>>> builds stable reliable wheels. but /not/ for the reasons stated! now,
>>>> how would a lay person know the difference? the limit of the typical
>>>> lay person's ability to follow the arguments presented depends on:
>>>> 1. presentation style
>>>> 2. appeal to alma mater authority
>>>> 3. success in follow wheel build instructions.
>>>> however, /if/ you're a techie and you want to follow the engineering
>>>> arguments in xy's book, you find all kinds of problems.
>>>> there are many, but they include:
>>>> 1. use of the wrong stress/strain graph to explain spoke deformation.
>>>> 2. use of the above to construct a "stress relief" theory - which also
>>>> takes no account of the body of fatigue research accumulated over more
>>>> than 100 years.
>>>> 3. misattribution of rim cracking to anodizing based on an inappropriate
>>>> dye penetrant test.
>>>> 4. misrepresenting a load calculation to be a strength calculation.
>>>> 5. neglecting spoke stiffness when attempting to calculate tensiometer
>>>> deflection.
>>>> and so on.
>>>> the point is, under /technical/ scrutiny, there are problems ranging
>>>> from simple mistakes through to outright fabrication. but how will a
>>>> lay person know that and therefore be able to judge? instead, again,
>>>> they're relying on
>>>> 1. presentation style
>>>> 2. appeal to alma mater authority
>>>> 3. success in follow wheel build instructions.
>>>> and are therefore susceptible to suggestion if the "expert" wants to
>>>> extrapolate credibility.
>>>> which leads to examination of the audience. xy has chosen to promote
>>>> themselves to a carefully selected audience. the success of that is a
>>>> matter of human nature since the selected target audience has no way of
>>>> easily determining the truth.
>>>> as an example, there are regularly cases where individuals impersonate
>>>> doctors.
>>>> http://www.signonsandiego.com/uniontrib/20060929/news_7m29raupp.htmlh...
>>>> these individuals talk the talk, are highly convincing, even hold down
>>>> jobs, in some cases for years. but in reality, they're frauds. they're
>>>> very clever people exploiting human gullibility and reliance on "expert"
>>>> status, but frauds nonetheless.
>>>> another example would be computer hackers. a true technical "crack" is
>>>> pretty geeky and hard to achieve. so most break-in's don't occur that
>>>> way, most system break-in's occur via "social engineering". iow,
>>>> talking a convincing talk to someone sufficiently gullible that they
>>>> give away the information necessary to gain system access. and this
>>>> happens all the time. that's why "phishing" works.
>>>> bottom line, doctor impersonators don't show up at medical symposiums
>>>> and try to present research to /real/ experts - they'll be discovered in
>>>> no time. instead, they
>>>> ...
>>>> read more ?
>>> Problem is that the other techies in the group seem to agree with XY's
>>> theories and not with PQs theories. In fact, a couple of the techies
>>> that support XY are often referred to in bicycling magazines work at
>>> respectable bike shops and are also well known experts. Yet, most of
>>> the other techies do not agree with PQ.
>> here's the problem with that argument - none of these "techies" spotted
>> any of the problems in "the book" before. if they're such reliable
>> experts, why not?
>>
>>
>>
>>> PQ argues that the other techies are not really techies and don't know
>>> what they are talking about. But how are the inexperienced suppossed
>>> to know that PQ is right? And, what is worng with the other techies?
>>> have they been so brain washed but XY that they cannot differentiate
>>> good from bad? Well, I would doubt it. some of the techies work on
>>> wheels using XY's approach and PQ's approach daily. In fact, since
>>> they are bike shop mechanics, they can actually compare the two
>>> approaches in their daily work. They end up favoring XY's, because
>>> they see less failure.
>> but the wheel build practice is good. that's been said repeatedly. and
>> it predates the author by at least half a century. it's the proposed
>> theory that's rubbish. it's based on misunderstanding and underinformed
>> presumption. you don't have to take any body's word for it - you can
>> see for yourself. check out the wheel load calcs - no accounting for
>> wheel strength there. check out the tensiometer math - no accounting
>> for spoke stiffness there. check out the stress/strain graph cited for
>> "stress relief" theory, then compare it with the real stress/strain
>> graphs at the back. real spokes show no strain aging. can't build a
>> theory using strain aging as a deformation mechanism if it doesn't exist.
>>
>>
>>
>>> In my case, I have have bought bicycles that do not come up with XY's
>>> equipment. they usually come with the latest most technologically
>>> advanced stuff that advertisers will claim to offer. As some of the
>>> equipment fails and I need to repair or replace it, I go with XY's
>>> suggestions since they are cheaper, easier and more durable.
>>> The doctor's example is a good one. I have an illness. I look for
>>> treatment and there are lots of references to Xs treatment. In fact,
>>> there are pictures of patients of X that have been treated by him and
>>> seem to be better. X has published a book about his treatment, and is
>>> often referred to by other doctors as an expert in the field. Other
>>> doctors prescribe his treatment with success. X works at a well
>>> established hospital, consults for a respected pharma and yet, he
>>> doesn't seem to promote a certain brand or looking to make a buck. The
>>> other doctors that prescribe X's treatment are also well established
>>> and work for major clinics in the country.
>>> Another individual "Y" of unknown qualifications claims that while X's
>>> treatment works it is based in wrong principles, is old fashioned and
>>> there are better treatments. Although, he cannot find support among
>>> the other experts about his claims or the alternative treatment that
>>> he is proposing. When other doctor's challenge Y and tell him that X
>>> is right on, Y tells the other doctors that they don't know what he is
>>> talking about. What shall the choice of doctors of the lay person be?
>>> Of course, there are geniuses in the world that go against the current
>>> and it turns out that they are right. Maybe, Y and PQ are
>>> misunderstood geniuses.Who knows. All I can say is what I often tell a
>>> student that doesnt' like me and wants to plot something against me. I
>>> usually say that if he doesn't like me, but the rest of the class
>>> does, the chances of being able to subvert my authority are slim. On
>>> the other hand, if he can get some allies then, a larger group can
>>> subvert my authority. I tell the same thing to my employees. If one
>>> employee has a grievance against another one that everyone seems to
>>> like and get along with, the chances of people listening to his or her
>>> grievance are slim. The same applies to knowledge. If someone wants to
>>> challenge a well established authority, then he needs some support. It
>>> the challenger cannot get support from experts or demonstrate
>>> objectively that the new knowledge is better, then he has a slim
>>> chance of being listened to and a greater one of being labeled a
>>> wacko. As I said, maybe the challenger is a misunderstood genius.
>>> However, for a genius to waste his breath and be labeled a wacko for a
>>> mere bike wheel is hardly worth it to me.
>> so shut up and let you enjoy having smoke blown up your kilt in peace?
>> whatever floats your boat dude! but i doubt you'd feel the same if
>> someone started posting wrong, but pseudo "expert" information on a
>> subject on which /you/ happened to have detailed and specific knowledge
>> to the contrary. especially if they were doing it as a means of selling
>> you something.
>
> Actually, the subjects that I have expertise in, I can site sources
> that will back up my knowledge, evidence that something that I propose
> works, colleagues who have tried using the same techniques with
> positive results. If someone presented pseudo expert information, and
> they often do in my field, I can pretty much articulate the reasons
> for, in my field, XY's arguments are wrong. I can site my own work as
> well as the work of others to show that something is nonsense. In
> fact, I have to do this often. I never argue that I am right because I
> am an expert and therefore I know that the other dude is a "pseudo".
> If i did that I would be laughed out of my profession. I often have to
> refer to other established practitioners to back up my contentions.
>
> With regards to XY vs PQ in wheel building, there seems to be nobody
> that PQ can refer to except himself who claims that XY is a pseudo
> expert. IF a pseudo expert in my field presents a theory that all the
> other experts buy into and I am the only one that disagrees with, then
> I cease to be the expert. This is referred to as paradigm shift. Once
> the accepted knowledge in a field is that XY's theories are valid,
> then XY's theories represent the dominant paradigm in wheelbuilding.
in terms of wheel assembly, they represent industry practice that
existed from /way/ back. in terms of theory, a lot of it is b.s.
"dominant paradigm" comes from relentless self-promotion to a selected
audience that has never bothered to check the math or crack open a
materials book. [references!] if these theories of "stress relief",
were presented to a symposium of materials experts, they laugh their
asses off. etc.
> For the dominant paradigm to shift, PQ will have to cite experts that
> support PQ's theories.
so what does the ability to successfully assemble a wheel tell you about
fatigue in non-strain aging materials? what does it tell you about
pre-stressed structure theory? what does it tell you about tensiometer
math? the point is, "credibility" in wheel assembly is /NOT/
credibility in engineering theory! that's the mistake of your argument.
|
| |
Date: 22 Jul 2007 15:56:12
From: andresmuro@aol.com
Subject: Re: spoke tension
|
On Jul 22, 3:25 pm, jim beam <spamvor...@bad.example.net > wrote:
> andresm...@aol.com wrote:
> > On Jul 17, 11:33 pm, jim beam <spamvor...@bad.example.net> wrote:
> >> jobst.bra...@stanfordalumni.org wrote:
> >>>http://www.jimbeam.com/beam/default.aspx?writes:
> >>>>>>> Could someone recommend the proper spoke tension for a rear wheel
> >>>>>>> built with a Velocity Aerohead OC rim?
> >>>>>> JB says tension as high as the rim will bear without taking a
> >>>>>> "taco" or "potato chip" shape; however, jb says tension only as
> >>>>>> high as the manufacturer's recommendation, or the rim will crack
> >>>>>> around the spoke hole.
> >>>>>> LET THE BATTLE BEGIN!
> >>>>> That's not really what Jobst says. It's what jim beam says Jobst
> >>>>> says, which are usually two (often very) different things. I guess
> >>>>> you didn't read the book, either.
> >>>> "as high as the rim can bear" is what jobst says on this group.
> >>>> "spokes must be as tight as the rim permits" is what he says in "the
> >>>> book". [3rd edition.]
> >>>> either way, he equates increasing spoke tension with increasing
> >>>> wheel strength: "a wheel with spoke tension near the limit of rim
> >>>> strength can support large loads easily" - which is untrue,
> >>>> misleading and reveals gross misunderstanding.
> >>> I think such statements need a bit of evidence to be credible.
> >>> A wire spoked bicycle wheel can carry loads up to the point where its
> >>> spokes become slack from compression as they pass the load point on
> >>> the road. The looser the spokes the more easily this occurs and
> >>> conversely the tighter the spoke the less this occurs.
> >> as discussed on several prior occasions, you are only considering the
> >> spokes, not the rim. increasing spoke tension increases circumferenti=
al
> >> rim compression. but you miss the point that as the rim's compression
> >> rises, its load capacity decreases.
>
> >> let's assume an aluminum beam has the same tensile strength as it does
> >> compression. let's say that it yields at [pick a number] +/- 100Mpa.
> >> in plain bending, the compressive side yields at the same time as the
> >> tensile side - when this limit is reached. now, compress the beam
> >> longitudinally at say 50Mpa, i.e. superimpose a stress on it. the
> >> tensile side of the beam can now support 100 + 50 =3D 150Mpa before yi=
eld.
> >> but the compressive side can only support 100 - 50 =3D 50Mpa. so if=
i
> >> bend it now, the beam will start to yield supporting only half the load
> >> it did before.
>
> >> with materials with no tensile strength like concrete, you "borrow" fr=
om
> >> the material's [ample] compressive strength to give it pseudo tensile
> >> strength. but with a material as strong in compression as tension, li=
ke
> >> an aluminum bike rim, that's simply counter-productive.
>
> >> in your book, you also argue that rims collapse as soon as spokes go
> >> slack go slack....http://www.flickr.com/photos/38636024@N00/417157612/
>
> >> writing a book is one thing. understanding what to put in it is quite
> >> another.
>
> >>> I have ridden many 100k miles with wheels tensioned as described
> >>> without needing to re-true them or to replace cracked rims. These
> >>> have been socketed tubular rims (Fiamme, Super Champion, and Mavic)
> >>> and Super Champion "Gentleman" and Mavic MA-2 clincher rims. I still
> >>> ride the latter as do most of my fellow riders, ones who do not see
> >>> themselves as professional like racers..
> >>> When riding rough roads such as described in rec.bicycles.rides "Last
> >>> chance road", I and my bikie friends wonder if the light weight "with
> >>> it" crowd ever experience roads that are demanding on 36-spoke wheels.
> >>>http://tinyurl.com/2uc6tb
> >>> Dings in rims also come from insufficient inflation, a parallel to
> >>> insufficient spoke tension in supporting loads.
> >>>http://geocities.com/rayhosler/slideshow.html
> >>> Ride bike!
> >> red herring.
>
> > This is the dilemma that many people have:
>
> > They want advise on wheels and they look for an expert's opinion.
> > There are two guys who respond. One says: "wheel X with Y
> > characteristics is ideal." The other one says: "wheel P with Q
> > characteristics is ideal" both offer contradictory info with some
> > technical and inaccessible explanations for non engineers.
>
> > so, people have to decide which poster to believe. Poster XY has
> > published a book that is often referred to by bicycle people who
> > regularly build and sell wheels, shop owners, cyclists, and other
> > sport aficionados. Poster XY also post pictures in which he rides
> > with XY wheels in dirt roads, endless hills, tours of Europe, and post
> > pictures of his friends riding XY wheels with the same
> > characteristics. Poster XY is a regular consultant for Avocet, and
> > gets hired to test the products. In other words, poster XY has
> > established a solid reputation as an expert in the field and can site
> > a history of expertise and product testing. Moreover, Poster XY
> > doesn't appear to be affiliated or to receive compensation for many of
> > the ideas or products that he endorses.
>
> > Now, Poster PQ post under a pseudonym. So we don't know if he has ever
> > published anything. The regular wheel builders in the community and
> > the shop owners do not seem to endorse him. We don't know if he rides
> > what he claims to support and has in no established credibility.
>
> > It is possible that PQs arguments are all valid. But, for those who
> > lack expertise to understand the explanations, credibility is
> > important. It is like reading a research paper with no notes and
> > references vs one in which all the referred information is noted,
> > referenced and backed.
> > When people disagree with poster PQ, he becomes verbally abusive in
> > frustration.
>
> > If poster's PQ arguments were valid, it is very unfortunate. His lack
> > of credibility prevents his knowledge from being disseminated. Is
> > there any way that poster PQ can back up his arguments by citing the
> > millions of wheels that he has built for friends and customers? Can ha
> > document the millions of miles that he has biked on his wheels? Can
> > he cite companies that have consulted with him and referred to his
> > ideas?
>
> > I think that poster PQ needs to find a way to document that his ways
> > have resulted in thousands of wheels being built, thousands of miles
> > being ridden and a following from other aficionados. If he could build
> > that kind of reputation, then we could have more interesting
> > exchanges.
>
> > I, myself have built wheels following poster XY with great success. In
> > fact, being a fatso and a cheapskate, I like XY's ideas, because they
> > are cost effective and durable and provide many miles of riding. In
> > fact, my bikes have inexpensive boring looking wheels a la XY. Would I
> > build wheels following PQ's advise? Not now, based on his current
> > reputation.
>
> > Just my thoughts,
>
> > Andres
>
> whether or not you like pq's style really isn't the issue. if you don't
> like it, don't read it. instead, let's look at the, er, "success" of
> xy's schtick and how it depends on audience.
>
> if the audience doesn't know all the technical facts, they rely for
> judgment on the nature of presentation, appeal to alma mater authority
> and whether the relatively small proportion of things they /can/ test
> actually work. in the case of wheel building technique, xy's method
> does indeed work. "stress relief" as a process "works" in that it
> builds stable reliable wheels. but /not/ for the reasons stated! now,
> how would a lay person know the difference? the limit of the typical
> lay person's ability to follow the arguments presented depends on:
>
> 1. presentation style
> 2. appeal to alma mater authority
> 3. success in follow wheel build instructions.
>
> however, /if/ you're a techie and you want to follow the engineering
> arguments in xy's book, you find all kinds of problems.
>
> there are many, but they include:
> 1. use of the wrong stress/strain graph to explain spoke deformation.
> 2. use of the above to construct a "stress relief" theory - which also
> takes no account of the body of fatigue research accumulated over more
> than 100 years.
> 3. misattribution of rim cracking to anodizing based on an inappropriate
> dye penetrant test.
> 4. misrepresenting a load calculation to be a strength calculation.
> 5. neglecting spoke stiffness when attempting to calculate tensiometer
> deflection.
>
> and so on.
>
> the point is, under /technical/ scrutiny, there are problems ranging
> from simple mistakes through to outright fabrication. but how will a
> lay person know that and therefore be able to judge? instead, again,
> they're relying on
>
> 1. presentation style
> 2. appeal to alma mater authority
> 3. success in follow wheel build instructions.
>
> and are therefore susceptible to suggestion if the "expert" wants to
> extrapolate credibility.
>
> which leads to examination of the audience. xy has chosen to promote
> themselves to a carefully selected audience. the success of that is a
> matter of human nature since the selected target audience has no way of
> easily determining the truth.
>
> as an example, there are regularly cases where individuals impersonate
> doctors.
>
> http://www.signonsandiego.com/uniontrib/20060929/news_7m29raupp.htmlhttp:=
//www.local10.com/news/8830685/detail.html
>
> these individuals talk the talk, are highly convincing, even hold down
> jobs, in some cases for years. but in reality, they're frauds. they're
> very clever people exploiting human gullibility and reliance on "expert"
> status, but frauds nonetheless.
>
> another example would be computer hackers. a true technical "crack" is
> pretty geeky and hard to achieve. so most break-in's don't occur that
> way, most system break-in's occur via "social engineering". iow,
> talking a convincing talk to someone sufficiently gullible that they
> give away the information necessary to gain system access. and this
> happens all the time. that's why "phishing" works.
>
> bottom line, doctor impersonators don't show up at medical symposiums
> and try to present research to /real/ experts - they'll be discovered in
> no time. instead, they
> ...
>
> read more =BB
Problem is that the other techies in the group seem to agree with XY's
theories and not with PQs theories. In fact, a couple of the techies
that support XY are often referred to in bicycling magazines work at
respectable bike shops and are also well known experts. Yet, most of
the other techies do not agree with PQ.
PQ argues that the other techies are not really techies and don't know
what they are talking about. But how are the inexperienced suppossed
to know that PQ is right? And, what is worng with the other techies?
have they been so brain washed but XY that they cannot differentiate
good from bad? Well, I would doubt it. some of the techies work on
wheels using XY's approach and PQ's approach daily. In fact, since
they are bike shop mechanics, they can actually compare the two
approaches in their daily work. They end up favoring XY's, because
they see less failure.
In my case, I have have bought bicycles that do not come up with XY's
equipment. they usually come with the latest most technologically
advanced stuff that advertisers will claim to offer. As some of the
equipment fails and I need to repair or replace it, I go with XY's
suggestions since they are cheaper, easier and more durable.
The doctor's example is a good one. I have an illness. I look for
treatment and there are lots of references to Xs treatment. In fact,
there are pictures of patients of X that have been treated by him and
seem to be better. X has published a book about his treatment, and is
often referred to by other doctors as an expert in the field. Other
doctors prescribe his treatment with success. X works at a well
established hospital, consults for a respected pharma and yet, he
doesn't seem to promote a certain brand or looking to make a buck. The
other doctors that prescribe X's treatment are also well established
and work for major clinics in the country.
Another individual "Y" of unknown qualifications claims that while X's
treatment works it is based in wrong principles, is old fashioned and
there are better treatments. Although, he cannot find support among
the other experts about his claims or the alternative treatment that
he is proposing. When other doctor's challenge Y and tell him that X
is right on, Y tells the other doctors that they don't know what he is
talking about. What shall the choice of doctors of the lay person be?
Of course, there are geniuses in the world that go against the current
and it turns out that they are right. Maybe, Y and PQ are
misunderstood geniuses.Who knows. All I can say is what I often tell a
student that doesnt' like me and wants to plot something against me. I
usually say that if he doesn't like me, but the rest of the class
does, the chances of being able to subvert my authority are slim. On
the other hand, if he can get some allies then, a larger group can
subvert my authority. I tell the same thing to my employees. If one
employee has a grievance against another one that everyone seems to
like and get along with, the chances of people listening to his or her
grievance are slim. The same applies to knowledge. If someone wants to
challenge a well established authority, then he needs some support. It
the challenger cannot get support from experts or demonstrate
objectively that the new knowledge is better, then he has a slim
chance of being listened to and a greater one of being labeled a
wacko. As I said, maybe the challenger is a misunderstood genius.
However, for a genius to waste his breath and be labeled a wacko for a
mere bike wheel is hardly worth it to me.
Andres
|
| | |
Date: 23 Jul 2007 04:16:24
From: Ben C
Subject: Re: spoke tension
|
On 2007-07-22, andresmuro@aol.com <andresmuro@aol.com > wrote:
[...]
> Problem is that the other techies in the group seem to agree with XY's
> theories and not with PQs theories.
If you read between the lines a bit the disagreements between XY and PQ
on how to actually build a wheel are not actually so great.
XY might say for example use a lot of spoke tension, but will also be
quick to point out that if you do that on an MA3 or some modern Mavic
rims without sockets then you can expect cracked rims-- just what PQ
says. The facts are similar, it's just that XY says use a different rim
in the first place, PQ says why not use less tension. They both have
points really.
|
| | | |
Date: 23 Jul 2007 06:14:27
From: jim beam
Subject: Re: spoke tension
|
Ben C wrote:
> On 2007-07-22, andresmuro@aol.com <andresmuro@aol.com> wrote:
> [...]
>> Problem is that the other techies in the group seem to agree with XY's
>> theories and not with PQs theories.
>
> If you read between the lines a bit the disagreements between XY and PQ
> on how to actually build a wheel are not actually so great.
except that i'm not interested in telling people how to build wheels. i
/am/ interested in making sure people correctly understand materials
theory though, and half-baked "stress relief" theories based on
misunderstanding and presumption is simply unacceptable.
>
> XY might say for example use a lot of spoke tension, but will also be
> quick to point out that if you do that on an MA3 or some modern Mavic
> rims without sockets then you can expect cracked rims-- just what PQ
> says. The facts are similar, it's just that XY says use a different rim
> in the first place, PQ says why not use less tension. They both have
> points really.
|
| | | | |
Date: 23 Jul 2007 10:27:20
From: Ben C
Subject: Re: spoke tension
|
On 2007-07-23, jim beam <spamvortex@bad.example.net > wrote:
> Ben C wrote:
>> On 2007-07-22, andresmuro@aol.com <andresmuro@aol.com> wrote:
>> [...]
>>> Problem is that the other techies in the group seem to agree with XY's
>>> theories and not with PQs theories.
>>
>> If you read between the lines a bit the disagreements between XY and PQ
>> on how to actually build a wheel are not actually so great.
>
> except that i'm not interested in telling people how to build wheels.
> i /am/ interested in making sure people correctly understand materials
> theory though, and half-baked "stress relief" theories based on
> misunderstanding and presumption is simply unacceptable.
Absolutely.
|
| | |
Date: 22 Jul 2007 18:22:40
From: jim beam
Subject: Re: spoke tension
|
andresmuro@aol.com wrote:
> On Jul 22, 3:25 pm, jim beam <spamvor...@bad.example.net> wrote:
>> andresm...@aol.com wrote:
>>> On Jul 17, 11:33 pm, jim beam <spamvor...@bad.example.net> wrote:
>>>> jobst.bra...@stanfordalumni.org wrote:
>>>>> http://www.jimbeam.com/beam/default.aspx?writes:
>>>>>>>>> Could someone recommend the proper spoke tension for a rear wheel
>>>>>>>>> built with a Velocity Aerohead OC rim?
>>>>>>>> JB says tension as high as the rim will bear without taking a
>>>>>>>> "taco" or "potato chip" shape; however, jb says tension only as
>>>>>>>> high as the manufacturer's recommendation, or the rim will crack
>>>>>>>> around the spoke hole.
>>>>>>>> LET THE BATTLE BEGIN!
>>>>>>> That's not really what Jobst says. It's what jim beam says Jobst
>>>>>>> says, which are usually two (often very) different things. I guess
>>>>>>> you didn't read the book, either.
>>>>>> "as high as the rim can bear" is what jobst says on this group.
>>>>>> "spokes must be as tight as the rim permits" is what he says in "the
>>>>>> book". [3rd edition.]
>>>>>> either way, he equates increasing spoke tension with increasing
>>>>>> wheel strength: "a wheel with spoke tension near the limit of rim
>>>>>> strength can support large loads easily" - which is untrue,
>>>>>> misleading and reveals gross misunderstanding.
>>>>> I think such statements need a bit of evidence to be credible.
>>>>> A wire spoked bicycle wheel can carry loads up to the point where its
>>>>> spokes become slack from compression as they pass the load point on
>>>>> the road. The looser the spokes the more easily this occurs and
>>>>> conversely the tighter the spoke the less this occurs.
>>>> as discussed on several prior occasions, you are only considering the
>>>> spokes, not the rim. increasing spoke tension increases circumferential
>>>> rim compression. but you miss the point that as the rim's compression
>>>> rises, its load capacity decreases.
>>>> let's assume an aluminum beam has the same tensile strength as it does
>>>> compression. let's say that it yields at [pick a number] +/- 100Mpa.
>>>> in plain bending, the compressive side yields at the same time as the
>>>> tensile side - when this limit is reached. now, compress the beam
>>>> longitudinally at say 50Mpa, i.e. superimpose a stress on it. the
>>>> tensile side of the beam can now support 100 + 50 = 150Mpa before yield.
>>>> but the compressive side can only support 100 - 50 = 50Mpa. so if i
>>>> bend it now, the beam will start to yield supporting only half the load
>>>> it did before.
>>>> with materials with no tensile strength like concrete, you "borrow" from
>>>> the material's [ample] compressive strength to give it pseudo tensile
>>>> strength. but with a material as strong in compression as tension, like
>>>> an aluminum bike rim, that's simply counter-productive.
>>>> in your book, you also argue that rims collapse as soon as spokes go
>>>> slack go slack....http://www.flickr.com/photos/38636024@N00/417157612/
>>>> writing a book is one thing. understanding what to put in it is quite
>>>> another.
>>>>> I have ridden many 100k miles with wheels tensioned as described
>>>>> without needing to re-true them or to replace cracked rims. These
>>>>> have been socketed tubular rims (Fiamme, Super Champion, and Mavic)
>>>>> and Super Champion "Gentleman" and Mavic MA-2 clincher rims. I still
>>>>> ride the latter as do most of my fellow riders, ones who do not see
>>>>> themselves as professional like racers..
>>>>> When riding rough roads such as described in rec.bicycles.rides "Last
>>>>> chance road", I and my bikie friends wonder if the light weight "with
>>>>> it" crowd ever experience roads that are demanding on 36-spoke wheels.
>>>>> http://tinyurl.com/2uc6tb
>>>>> Dings in rims also come from insufficient inflation, a parallel to
>>>>> insufficient spoke tension in supporting loads.
>>>>> http://geocities.com/rayhosler/slideshow.html
>>>>> Ride bike!
>>>> red herring.
>>> This is the dilemma that many people have:
>>> They want advise on wheels and they look for an expert's opinion.
>>> There are two guys who respond. One says: "wheel X with Y
>>> characteristics is ideal." The other one says: "wheel P with Q
>>> characteristics is ideal" both offer contradictory info with some
>>> technical and inaccessible explanations for non engineers.
>>> so, people have to decide which poster to believe. Poster XY has
>>> published a book that is often referred to by bicycle people who
>>> regularly build and sell wheels, shop owners, cyclists, and other
>>> sport aficionados. Poster XY also post pictures in which he rides
>>> with XY wheels in dirt roads, endless hills, tours of Europe, and post
>>> pictures of his friends riding XY wheels with the same
>>> characteristics. Poster XY is a regular consultant for Avocet, and
>>> gets hired to test the products. In other words, poster XY has
>>> established a solid reputation as an expert in the field and can site
>>> a history of expertise and product testing. Moreover, Poster XY
>>> doesn't appear to be affiliated or to receive compensation for many of
>>> the ideas or products that he endorses.
>>> Now, Poster PQ post under a pseudonym. So we don't know if he has ever
>>> published anything. The regular wheel builders in the community and
>>> the shop owners do not seem to endorse him. We don't know if he rides
>>> what he claims to support and has in no established credibility.
>>> It is possible that PQs arguments are all valid. But, for those who
>>> lack expertise to understand the explanations, credibility is
>>> important. It is like reading a research paper with no notes and
>>> references vs one in which all the referred information is noted,
>>> referenced and backed.
>>> When people disagree with poster PQ, he becomes verbally abusive in
>>> frustration.
>>> If poster's PQ arguments were valid, it is very unfortunate. His lack
>>> of credibility prevents his knowledge from being disseminated. Is
>>> there any way that poster PQ can back up his arguments by citing the
>>> millions of wheels that he has built for friends and customers? Can ha
>>> document the millions of miles that he has biked on his wheels? Can
>>> he cite companies that have consulted with him and referred to his
>>> ideas?
>>> I think that poster PQ needs to find a way to document that his ways
>>> have resulted in thousands of wheels being built, thousands of miles
>>> being ridden and a following from other aficionados. If he could build
>>> that kind of reputation, then we could have more interesting
>>> exchanges.
>>> I, myself have built wheels following poster XY with great success. In
>>> fact, being a fatso and a cheapskate, I like XY's ideas, because they
>>> are cost effective and durable and provide many miles of riding. In
>>> fact, my bikes have inexpensive boring looking wheels a la XY. Would I
>>> build wheels following PQ's advise? Not now, based on his current
>>> reputation.
>>> Just my thoughts,
>>> Andres
>> whether or not you like pq's style really isn't the issue. if you don't
>> like it, don't read it. instead, let's look at the, er, "success" of
>> xy's schtick and how it depends on audience.
>>
>> if the audience doesn't know all the technical facts, they rely for
>> judgment on the nature of presentation, appeal to alma mater authority
>> and whether the relatively small proportion of things they /can/ test
>> actually work. in the case of wheel building technique, xy's method
>> does indeed work. "stress relief" as a process "works" in that it
>> builds stable reliable wheels. but /not/ for the reasons stated! now,
>> how would a lay person know the difference? the limit of the typical
>> lay person's ability to follow the arguments presented depends on:
>>
>> 1. presentation style
>> 2. appeal to alma mater authority
>> 3. success in follow wheel build instructions.
>>
>> however, /if/ you're a techie and you want to follow the engineering
>> arguments in xy's book, you find all kinds of problems.
>>
>> there are many, but they include:
>> 1. use of the wrong stress/strain graph to explain spoke deformation.
>> 2. use of the above to construct a "stress relief" theory - which also
>> takes no account of the body of fatigue research accumulated over more
>> than 100 years.
>> 3. misattribution of rim cracking to anodizing based on an inappropriate
>> dye penetrant test.
>> 4. misrepresenting a load calculation to be a strength calculation.
>> 5. neglecting spoke stiffness when attempting to calculate tensiometer
>> deflection.
>>
>> and so on.
>>
>> the point is, under /technical/ scrutiny, there are problems ranging
>> from simple mistakes through to outright fabrication. but how will a
>> lay person know that and therefore be able to judge? instead, again,
>> they're relying on
>>
>> 1. presentation style
>> 2. appeal to alma mater authority
>> 3. success in follow wheel build instructions.
>>
>> and are therefore susceptible to suggestion if the "expert" wants to
>> extrapolate credibility.
>>
>> which leads to examination of the audience. xy has chosen to promote
>> themselves to a carefully selected audience. the success of that is a
>> matter of human nature since the selected target audience has no way of
>> easily determining the truth.
>>
>> as an example, there are regularly cases where individuals impersonate
>> doctors.
>>
>> http://www.signonsandiego.com/uniontrib/20060929/news_7m29raupp.htmlhttp://www.local10.com/news/8830685/detail.html
>>
>> these individuals talk the talk, are highly convincing, even hold down
>> jobs, in some cases for years. but in reality, they're frauds. they're
>> very clever people exploiting human gullibility and reliance on "expert"
>> status, but frauds nonetheless.
>>
>> another example would be computer hackers. a true technical "crack" is
>> pretty geeky and hard to achieve. so most break-in's don't occur that
>> way, most system break-in's occur via "social engineering". iow,
>> talking a convincing talk to someone sufficiently gullible that they
>> give away the information necessary to gain system access. and this
>> happens all the time. that's why "phishing" works.
>>
>> bottom line, doctor impersonators don't show up at medical symposiums
>> and try to present research to /real/ experts - they'll be discovered in
>> no time. instead, they
>> ...
>>
>> read more �
>
> Problem is that the other techies in the group seem to agree with XY's
> theories and not with PQs theories. In fact, a couple of the techies
> that support XY are often referred to in bicycling magazines work at
> respectable bike shops and are also well known experts. Yet, most of
> the other techies do not agree with PQ.
here's the problem with that argument - none of these "techies" spotted
any of the problems in "the book" before. if they're such reliable
experts, why not?
>
> PQ argues that the other techies are not really techies and don't know
> what they are talking about. But how are the inexperienced suppossed
> to know that PQ is right? And, what is worng with the other techies?
> have they been so brain washed but XY that they cannot differentiate
> good from bad? Well, I would doubt it. some of the techies work on
> wheels using XY's approach and PQ's approach daily. In fact, since
> they are bike shop mechanics, they can actually compare the two
> approaches in their daily work. They end up favoring XY's, because
> they see less failure.
but the wheel build practice is good. that's been said repeatedly. and
it predates the author by at least half a century. it's the proposed
theory that's rubbish. it's based on misunderstanding and underinformed
presumption. you don't have to take any body's word for it - you can
see for yourself. check out the wheel load calcs - no accounting for
wheel strength there. check out the tensiometer math - no accounting
for spoke stiffness there. check out the stress/strain graph cited for
"stress relief" theory, then compare it with the real stress/strain
graphs at the back. real spokes show no strain aging. can't build a
theory using strain aging as a deformation mechanism if it doesn't exist.
>
> In my case, I have have bought bicycles that do not come up with XY's
> equipment. they usually come with the latest most technologically
> advanced stuff that advertisers will claim to offer. As some of the
> equipment fails and I need to repair or replace it, I go with XY's
> suggestions since they are cheaper, easier and more durable.
>
> The doctor's example is a good one. I have an illness. I look for
> treatment and there are lots of references to Xs treatment. In fact,
> there are pictures of patients of X that have been treated by him and
> seem to be better. X has published a book about his treatment, and is
> often referred to by other doctors as an expert in the field. Other
> doctors prescribe his treatment with success. X works at a well
> established hospital, consults for a respected pharma and yet, he
> doesn't seem to promote a certain brand or looking to make a buck. The
> other doctors that prescribe X's treatment are also well established
> and work for major clinics in the country.
>
> Another individual "Y" of unknown qualifications claims that while X's
> treatment works it is based in wrong principles, is old fashioned and
> there are better treatments. Although, he cannot find support among
> the other experts about his claims or the alternative treatment that
> he is proposing. When other doctor's challenge Y and tell him that X
> is right on, Y tells the other doctors that they don't know what he is
> talking about. What shall the choice of doctors of the lay person be?
>
> Of course, there are geniuses in the world that go against the current
> and it turns out that they are right. Maybe, Y and PQ are
> misunderstood geniuses.Who knows. All I can say is what I often tell a
> student that doesnt' like me and wants to plot something against me. I
> usually say that if he doesn't like me, but the rest of the class
> does, the chances of being able to subvert my authority are slim. On
> the other hand, if he can get some allies then, a larger group can
> subvert my authority. I tell the same thing to my employees. If one
> employee has a grievance against another one that everyone seems to
> like and get along with, the chances of people listening to his or her
> grievance are slim. The same applies to knowledge. If someone wants to
> challenge a well established authority, then he needs some support. It
> the challenger cannot get support from experts or demonstrate
> objectively that the new knowledge is better, then he has a slim
> chance of being listened to and a greater one of being labeled a
> wacko. As I said, maybe the challenger is a misunderstood genius.
> However, for a genius to waste his breath and be labeled a wacko for a
> mere bike wheel is hardly worth it to me.
so shut up and let you enjoy having smoke blown up your kilt in peace?
whatever floats your boat dude! but i doubt you'd feel the same if
someone started posting wrong, but pseudo "expert" information on a
subject on which /you/ happened to have detailed and specific knowledge
to the contrary. especially if they were doing it as a means of selling
you something.
|
| |
Date: 22 Jul 2007 09:45:12
From: andresmuro@aol.com
Subject: Re: spoke tension
|
On Jul 17, 11:33 pm, jim beam <spamvor...@bad.example.net > wrote:
> jobst.bra...@stanfordalumni.org wrote:
> >http://www.jimbeam.com/beam/default.aspx?writes:
>
> >>>>> Could someone recommend the proper spoke tension for a rear wheel
> >>>>> built with a Velocity Aerohead OC rim?
>
> >>>> JB says tension as high as the rim will bear without taking a
> >>>> "taco" or "potato chip" shape; however, jb says tension only as
> >>>> high as the manufacturer's recommendation, or the rim will crack
> >>>> around the spoke hole.
>
> >>>> LET THE BATTLE BEGIN!
>
> >>> That's not really what Jobst says. It's what jim beam says Jobst
> >>> says, which are usually two (often very) different things. I guess
> >>> you didn't read the book, either.
>
> >> "as high as the rim can bear" is what jobst says on this group.
>
> >> "spokes must be as tight as the rim permits" is what he says in "the
> >> book". [3rd edition.]
>
> >> either way, he equates increasing spoke tension with increasing
> >> wheel strength: "a wheel with spoke tension near the limit of rim
> >> strength can support large loads easily" - which is untrue,
> >> misleading and reveals gross misunderstanding.
>
> > I think such statements need a bit of evidence to be credible.
>
> > A wire spoked bicycle wheel can carry loads up to the point where its
> > spokes become slack from compression as they pass the load point on
> > the road. The looser the spokes the more easily this occurs and
> > conversely the tighter the spoke the less this occurs.
>
> as discussed on several prior occasions, you are only considering the
> spokes, not the rim. increasing spoke tension increases circumferential
> rim compression. but you miss the point that as the rim's compression
> rises, its load capacity decreases.
>
> let's assume an aluminum beam has the same tensile strength as it does
> compression. let's say that it yields at [pick a number] +/- 100Mpa.
> in plain bending, the compressive side yields at the same time as the
> tensile side - when this limit is reached. now, compress the beam
> longitudinally at say 50Mpa, i.e. superimpose a stress on it. the
> tensile side of the beam can now support 100 + 50 = 150Mpa before yield.
> but the compressive side can only support 100 - 50 = 50Mpa. so if i
> bend it now, the beam will start to yield supporting only half the load
> it did before.
>
> with materials with no tensile strength like concrete, you "borrow" from
> the material's [ample] compressive strength to give it pseudo tensile
> strength. but with a material as strong in compression as tension, like
> an aluminum bike rim, that's simply counter-productive.
>
> in your book, you also argue that rims collapse as soon as spokes go
> slack go slack....http://www.flickr.com/photos/38636024@N00/417157612/
>
> writing a book is one thing. understanding what to put in it is quite
> another.
>
>
>
>
>
> > I have ridden many 100k miles with wheels tensioned as described
> > without needing to re-true them or to replace cracked rims. These
> > have been socketed tubular rims (Fiamme, Super Champion, and Mavic)
> > and Super Champion "Gentleman" and Mavic MA-2 clincher rims. I still
> > ride the latter as do most of my fellow riders, ones who do not see
> > themselves as professional like racers..
>
> > When riding rough roads such as described in rec.bicycles.rides "Last
> > chance road", I and my bikie friends wonder if the light weight "with
> > it" crowd ever experience roads that are demanding on 36-spoke wheels.
>
> >http://tinyurl.com/2uc6tb
>
> > Dings in rims also come from insufficient inflation, a parallel to
> > insufficient spoke tension in supporting loads.
>
> >http://geocities.com/rayhosler/slideshow.html
>
> > Ride bike!
>
> red herring.
This is the dilemma that many people have:
They want advise on wheels and they look for an expert's opinion.
There are two guys who respond. One says: "wheel X with Y
characteristics is ideal." The other one says: "wheel P with Q
characteristics is ideal" both offer contradictory info with some
technical and inaccessible explanations for non engineers.
so, people have to decide which poster to believe. Poster XY has
published a book that is often referred to by bicycle people who
regularly build and sell wheels, shop owners, cyclists, and other
sport aficionados. Poster XY also post pictures in which he rides
with XY wheels in dirt roads, endless hills, tours of Europe, and post
pictures of his friends riding XY wheels with the same
characteristics. Poster XY is a regular consultant for Avocet, and
gets hired to test the products. In other words, poster XY has
established a solid reputation as an expert in the field and can site
a history of expertise and product testing. Moreover, Poster XY
doesn't appear to be affiliated or to receive compensation for many of
the ideas or products that he endorses.
Now, Poster PQ post under a pseudonym. So we don't know if he has ever
published anything. The regular wheel builders in the community and
the shop owners do not seem to endorse him. We don't know if he rides
what he claims to support and has in no established credibility.
It is possible that PQs arguments are all valid. But, for those who
lack expertise to understand the explanations, credibility is
important. It is like reading a research paper with no notes and
references vs one in which all the referred information is noted,
referenced and backed.
When people disagree with poster PQ, he becomes verbally abusive in
frustration.
If poster's PQ arguments were valid, it is very unfortunate. His lack
of credibility prevents his knowledge from being disseminated. Is
there any way that poster PQ can back up his arguments by citing the
millions of wheels that he has built for friends and customers? Can ha
document the millions of miles that he has biked on his wheels? Can
he cite companies that have consulted with him and referred to his
ideas?
I think that poster PQ needs to find a way to document that his ways
have resulted in thousands of wheels being built, thousands of miles
being ridden and a following from other aficionados. If he could build
that kind of reputation, then we could have more interesting
exchanges.
I, myself have built wheels following poster XY with great success. In
fact, being a fatso and a cheapskate, I like XY's ideas, because they
are cost effective and durable and provide many miles of riding. In
fact, my bikes have inexpensive boring looking wheels a la XY. Would I
build wheels following PQ's advise? Not now, based on his current
reputation.
Just my thoughts,
Andres
|
| | |
Date: 22 Jul 2007 14:25:17
From: jim beam
Subject: Re: spoke tension
|
andresmuro@aol.com wrote:
> On Jul 17, 11:33 pm, jim beam <spamvor...@bad.example.net> wrote:
>> jobst.bra...@stanfordalumni.org wrote:
>>> http://www.jimbeam.com/beam/default.aspx?writes:
>>>>>>> Could someone recommend the proper spoke tension for a rear wheel
>>>>>>> built with a Velocity Aerohead OC rim?
>>>>>> JB says tension as high as the rim will bear without taking a
>>>>>> "taco" or "potato chip" shape; however, jb says tension only as
>>>>>> high as the manufacturer's recommendation, or the rim will crack
>>>>>> around the spoke hole.
>>>>>> LET THE BATTLE BEGIN!
>>>>> That's not really what Jobst says. It's what jim beam says Jobst
>>>>> says, which are usually two (often very) different things. I guess
>>>>> you didn't read the book, either.
>>>> "as high as the rim can bear" is what jobst says on this group.
>>>> "spokes must be as tight as the rim permits" is what he says in "the
>>>> book". [3rd edition.]
>>>> either way, he equates increasing spoke tension with increasing
>>>> wheel strength: "a wheel with spoke tension near the limit of rim
>>>> strength can support large loads easily" - which is untrue,
>>>> misleading and reveals gross misunderstanding.
>>> I think such statements need a bit of evidence to be credible.
>>> A wire spoked bicycle wheel can carry loads up to the point where its
>>> spokes become slack from compression as they pass the load point on
>>> the road. The looser the spokes the more easily this occurs and
>>> conversely the tighter the spoke the less this occurs.
>> as discussed on several prior occasions, you are only considering the
>> spokes, not the rim. increasing spoke tension increases circumferential
>> rim compression. but you miss the point that as the rim's compression
>> rises, its load capacity decreases.
>>
>> let's assume an aluminum beam has the same tensile strength as it does
>> compression. let's say that it yields at [pick a number] +/- 100Mpa.
>> in plain bending, the compressive side yields at the same time as the
>> tensile side - when this limit is reached. now, compress the beam
>> longitudinally at say 50Mpa, i.e. superimpose a stress on it. the
>> tensile side of the beam can now support 100 + 50 = 150Mpa before yield.
>> but the compressive side can only support 100 - 50 = 50Mpa. so if i
>> bend it now, the beam will start to yield supporting only half the load
>> it did before.
>>
>> with materials with no tensile strength like concrete, you "borrow" from
>> the material's [ample] compressive strength to give it pseudo tensile
>> strength. but with a material as strong in compression as tension, like
>> an aluminum bike rim, that's simply counter-productive.
>>
>> in your book, you also argue that rims collapse as soon as spokes go
>> slack go slack....http://www.flickr.com/photos/38636024@N00/417157612/
>>
>> writing a book is one thing. understanding what to put in it is quite
>> another.
>>
>>
>>
>>
>>
>>> I have ridden many 100k miles with wheels tensioned as described
>>> without needing to re-true them or to replace cracked rims. These
>>> have been socketed tubular rims (Fiamme, Super Champion, and Mavic)
>>> and Super Champion "Gentleman" and Mavic MA-2 clincher rims. I still
>>> ride the latter as do most of my fellow riders, ones who do not see
>>> themselves as professional like racers..
>>> When riding rough roads such as described in rec.bicycles.rides "Last
>>> chance road", I and my bikie friends wonder if the light weight "with
>>> it" crowd ever experience roads that are demanding on 36-spoke wheels.
>>> http://tinyurl.com/2uc6tb
>>> Dings in rims also come from insufficient inflation, a parallel to
>>> insufficient spoke tension in supporting loads.
>>> http://geocities.com/rayhosler/slideshow.html
>>> Ride bike!
>> red herring.
>
> This is the dilemma that many people have:
>
> They want advise on wheels and they look for an expert's opinion.
> There are two guys who respond. One says: "wheel X with Y
> characteristics is ideal." The other one says: "wheel P with Q
> characteristics is ideal" both offer contradictory info with some
> technical and inaccessible explanations for non engineers.
>
> so, people have to decide which poster to believe. Poster XY has
> published a book that is often referred to by bicycle people who
> regularly build and sell wheels, shop owners, cyclists, and other
> sport aficionados. Poster XY also post pictures in which he rides
> with XY wheels in dirt roads, endless hills, tours of Europe, and post
> pictures of his friends riding XY wheels with the same
> characteristics. Poster XY is a regular consultant for Avocet, and
> gets hired to test the products. In other words, poster XY has
> established a solid reputation as an expert in the field and can site
> a history of expertise and product testing. Moreover, Poster XY
> doesn't appear to be affiliated or to receive compensation for many of
> the ideas or products that he endorses.
>
> Now, Poster PQ post under a pseudonym. So we don't know if he has ever
> published anything. The regular wheel builders in the community and
> the shop owners do not seem to endorse him. We don't know if he rides
> what he claims to support and has in no established credibility.
>
> It is possible that PQs arguments are all valid. But, for those who
> lack expertise to understand the explanations, credibility is
> important. It is like reading a research paper with no notes and
> references vs one in which all the referred information is noted,
> referenced and backed.
> When people disagree with poster PQ, he becomes verbally abusive in
> frustration.
>
> If poster's PQ arguments were valid, it is very unfortunate. His lack
> of credibility prevents his knowledge from being disseminated. Is
> there any way that poster PQ can back up his arguments by citing the
> millions of wheels that he has built for friends and customers? Can ha
> document the millions of miles that he has biked on his wheels? Can
> he cite companies that have consulted with him and referred to his
> ideas?
>
> I think that poster PQ needs to find a way to document that his ways
> have resulted in thousands of wheels being built, thousands of miles
> being ridden and a following from other aficionados. If he could build
> that kind of reputation, then we could have more interesting
> exchanges.
>
> I, myself have built wheels following poster XY with great success. In
> fact, being a fatso and a cheapskate, I like XY's ideas, because they
> are cost effective and durable and provide many miles of riding. In
> fact, my bikes have inexpensive boring looking wheels a la XY. Would I
> build wheels following PQ's advise? Not now, based on his current
> reputation.
>
> Just my thoughts,
>
> Andres
>
>
>
whether or not you like pq's style really isn't the issue. if you don't
like it, don't read it. instead, let's look at the, er, "success" of
xy's schtick and how it depends on audience.
if the audience doesn't know all the technical facts, they rely for
judgment on the nature of presentation, appeal to alma mater authority
and whether the relatively small proportion of things they /can/ test
actually work. in the case of wheel building technique, xy's method
does indeed work. "stress relief" as a process "works" in that it
builds stable reliable wheels. but /not/ for the reasons stated! now,
how would a lay person know the difference? the limit of the typical
lay person's ability to follow the arguments presented depends on:
1. presentation style
2. appeal to alma mater authority
3. success in follow wheel build instructions.
however, /if/ you're a techie and you want to follow the engineering
arguments in xy's book, you find all kinds of problems.
there are many, but they include:
1. use of the wrong stress/strain graph to explain spoke deformation.
2. use of the above to construct a "stress relief" theory - which also
takes no account of the body of fatigue research accumulated over more
than 100 years.
3. misattribution of rim cracking to anodizing based on an inappropriate
dye penetrant test.
4. misrepresenting a load calculation to be a strength calculation.
5. neglecting spoke stiffness when attempting to calculate tensiometer
deflection.
and so on.
the point is, under /technical/ scrutiny, there are problems ranging
from simple mistakes through to outright fabrication. but how will a
lay person know that and therefore be able to judge? instead, again,
they're relying on
1. presentation style
2. appeal to alma mater authority
3. success in follow wheel build instructions.
and are therefore susceptible to suggestion if the "expert" wants to
extrapolate credibility.
which leads to examination of the audience. xy has chosen to promote
themselves to a carefully selected audience. the success of that is a
matter of human nature since the selected target audience has no way of
easily determining the truth.
as an example, there are regularly cases where individuals impersonate
doctors.
http://www.signonsandiego.com/uniontrib/20060929/news_7m29raupp.html
http://www.local10.com/news/8830685/detail.html
these individuals talk the talk, are highly convincing, even hold down
jobs, in some cases for years. but in reality, they're frauds. they're
very clever people exploiting human gullibility and reliance on "expert"
status, but frauds nonetheless.
another example would be computer hackers. a true technical "crack" is
pretty geeky and hard to achieve. so most break-in's don't occur that
way, most system break-in's occur via "social engineering". iow,
talking a convincing talk to someone sufficiently gullible that they
give away the information necessary to gain system access. and this
happens all the time. that's why "phishing" works.
bottom line, doctor impersonators don't show up at medical symposiums
and try to present research to /real/ experts - they'll be discovered in
no time. instead, they target an audience they /know/ they can fool.
now, knowing that, and discovering that the "expert" can't do the math
and gets confused about strain aging materials when trying to formulate
"stress relief" theory, what would that tell you about the presenter and
their intended audience?
|
| |
Date: 21 Jul 2007 12:52:51
From: Gary Young
Subject: Re: spoke tension
|
On Sat, 21 Jul 2007 10:39:04 -0700, Ron Ruff wrote:
> On Jul 18, 7:02 am, jim beam <spamvor...@bad.example.net> wrote:
>> how about you address the point of the posting: "...the wheel can
>> support loads only to the point where its spokes become loose. at this
>> point the wheel will collapse." jobst brandt. "the book". 3rd edition.
>
> Maybe an exaggeration... but close to the truth. When spokes become
> slack they no longer provide support to the rim, so the rim is sort of
> on it's own. It's stiffness and strength and resistance to buckling
> drops a lot.
I wouldn't go so far as to call it an exaggeration until "jim beam"
supplies a page reference (he's ignored my request for that). Jobst is
usually careful to say that a slack wheel is vulnerable primarily to side
loads. "Jim beam" may well have quoted selectively to obscure the context.
Furthermore, even if Jobst exaggerated at one point, it's simply sophistry
to ignore the qualifying remarks he makes at other points in the book.
|
| | |
Date: 21 Jul 2007 12:44:51
From:
Subject: Re: spoke tension
|
On Sat, 21 Jul 2007 12:52:51 -0500, Gary Young <garyyoung3@gmail.com >
wrote:
>On Sat, 21 Jul 2007 10:39:04 -0700, Ron Ruff wrote:
>
>> On Jul 18, 7:02 am, jim beam <spamvor...@bad.example.net> wrote:
>>> how about you address the point of the posting: "...the wheel can
>>> support loads only to the point where its spokes become loose. at this
>>> point the wheel will collapse." jobst brandt. "the book". 3rd edition.
>>
>> Maybe an exaggeration... but close to the truth. When spokes become
>> slack they no longer provide support to the rim, so the rim is sort of
>> on it's own. It's stiffness and strength and resistance to buckling
>> drops a lot.
>
>I wouldn't go so far as to call it an exaggeration until "jim beam"
>supplies a page reference (he's ignored my request for that). Jobst is
>usually careful to say that a slack wheel is vulnerable primarily to side
>loads. "Jim beam" may well have quoted selectively to obscure the context.
>Furthermore, even if Jobst exaggerated at one point, it's simply sophistry
>to ignore the qualifying remarks he makes at other points in the book.
Dear Gary,
You're interested in textual references? How nice! There's nothing
like a good discussion of the vexing problem of how to cut and paste
together a version of Hamlet that combines the various quartos
(published without Shakespeare's consent during his lifetime) with the
version found in the First Folio of 1623, published also without his
consent, seven years after his death. Unlike Macbeth, for which we
have only the First Folio version and thus no scholarly debate--
Oh, you're only interested in "The Bicycle Wheel"?
Well, there are three English editions of Jobst's book, plus one in
German that we will ignore.
The two later editions add a little material and subtract a little
material, but they mainly reword things, often sentence by sentence.
This inch-by-inch rephrasing makes it horribly difficult to find a
particular passage.
Even worse from a scholarly point of view, the theoretical material in
the first part is often repeated in the second practical part, so you
may be looking at the wrong end of the book.
Frequently the reader hits an it's-explained-elsewhere comment, but
there's no page number given and no index.
(A scanned and searchable version obtained from unethical sources
helps immensely. Anyone willing to profit from piracy is welcome to
ask me to search for a phrase from the 3rd edition, since it only
takes a few moments.)
To be fair, Jobst was no more writing for scholars than Shakespeare
was, and Jim faces a hideous scholarly task if he wants to footnote
properly.
***
Here's the first edition (1981, 1983), illustrated by Sherry
Sheffield-Boulton, p. 78:
SPOKE TENSION
The correct tension for a wheel must be a balance between rim strength
and wheel stability. The spokes should be as tight as the rim permits
for maxium strength. However, for practical reasonss the spokes should
be slightly looser than this because at the maximum tension, the
failure of one spoke may destroy the rim.
***
Here's the second edition (1981, 1983, 1988, 7th printing 1990),
illustrated by Sherry Sheffield Boulton (no dash), p. 76:
SPOKE TENSION
The correct tension for a wheel is a balance between rim strength and
wheel stability. For greatest strength, spokes should be as tight as
the rim permits. In practice, however, spokes should be slightly
looser because when they are at the limit, failure of a single spoke
can severely deform the rim.
***
And here's the third edition (1993), illustrated by Sherry Sheffield
(no Boulton), page 71:
SPOKE TENSION
With tensioned wires as spokes, the wheel can support loads only to
the point where its spokes become loose. At this point the wheel will
collapse. Therefore, for greatest strength, spokes must be as tight as
the rim permits. . . .
[skip the rest of the paragraph and jump ~80 words to where the next
sentence has been moved]
In practice, however, spokes should be slightly looser than the
maximum the rim can sustain, because at maximum tension, failure of a
single spoke can severely deform the rim.
***
I defy anyone to find a more trivial example of the trivial changes
between the three editions than the illustrator's name (which may have
been far from trivial to her).
Anyway, there's the text and the page numbers and some explanation why
quoting from various editions of "The Bicycle Wheel" is something that
only the truly pedantic can enjoy.
Cheers,
Carl Fogel
|
| | | |
Date: 22 Jul 2007 05:22:01
From: Michael Press
Subject: Re: spoke tension
|
In article
<k1j4a3t46jo5s0jnnpaki3cv37cqu131p0@4ax.com >,
carlfogel@comcast.net wrote:
> There's nothing
> like a good discussion of the vexing problem of how to cut and paste
> together a version of Hamlet that combines the various quartos
> (published without Shakespeare's consent during his lifetime) with the
His consent is irrelevant since everybody knows
Edward de Vere, 17th Earl of Oxford wrote the plays.
> version found in the First Folio of 1623, published also without his
> consent, seven years after his death.
--
Michael Press
|
| | | | |
Date: 22 Jul 2007 15:53:43
From: still me
Subject: Re: spoke tension
|
On Sun, 22 Jul 2007 05:22:01 GMT, Michael Press <rubrum@pacbell.net >
wrote:
>His consent is irrelevant since everybody knows
>Edward de Vere, 17th Earl of Oxford wrote the plays.
You're wrong... I didn't know that.
Then again, I think Shakespeare sucks, so it's not surprising!
|
| | | |
Date: 21 Jul 2007 22:11:42
From: Tosspot
Subject: Re: spoke tension
|
carlfogel@comcast.net wrote:
<snip quoted text >
> I defy anyone to find a more trivial example of the trivial changes
> between the three editions than the illustrator's name (which may have
> been far from trivial to her).
>
> Anyway, there's the text and the page numbers and some explanation why
> quoting from various editions of "The Bicycle Wheel" is something that
> only the truly pedantic can enjoy.
Stop it Carl, you're spoiling a good fight that could go on for months!
After this I shall be building my wheels with half the spokes tensioned
to the max, a quarter untensioned, 2/5s missing completely and the rest
perpendicular to the lines of load!
Hmmmm...no ones mentioned the Citreon Mono Spoke yet...
|
| |
Date: 21 Jul 2007 12:41:52
From: Gary Young
Subject: Re: spoke tension
|
On Sat, 21 Jul 2007 09:38:15 -0700, jim beam wrote:
> Gary Young wrote:
>> On Sat, 21 Jul 2007 09:24:11 -0700, jim beam wrote:
>>
>>> Gary Young wrote:
>>>> On Sat, 21 Jul 2007 09:03:50 -0700, jim beam wrote:
>>>>
>>>>> Gary Young wrote:
>>>>>> On Fri, 20 Jul 2007 18:53:12 -0700, jim beam wrote:
>>>>>>
>>>>>>> Gary Young wrote:
>>>>>>>> On Thu, 19 Jul 2007 05:54:37 -0700, jim beam wrote:
>>>>>>>>
>>>>>>>>> Gary Young wrote:
>>>>>>>>>> On Wed, 18 Jul 2007 21:43:17 -0700, jim beam wrote:
>>>>>>>>>>
>>>>>>>>>>> Johnny Sunset aka Tom Sherman wrote:
>>>>>>>>>>>> "jim beam" ? wrote:
>>>>>>>>>>>>> Johnny Sunset aka Tom Sherman wrote:
>>>>>>>>>>>>>> "jim beam" ? wrote:
>>>>>>>>>>>>>>> ...
>>>>>>>>>>>>>>> in your book, you also argue that rims collapse as soon as spokes go
>>>>>>>>>>>>>>> slack go slack....
>>>>>>>>>>>>>>> http://www.flickr.com/photos/38636024@N00/417157612/
>>>>>>>>>>>>>> How far did you ride on that wheel?
>>>>>>>>>>>>>>
>>>>>>>>>>>>> as far as i could without the tensiometer falling off... wise guy.
>>>>>>>>>>>>>
>>>>>>>>>>>>> how about you address the point of the posting: "...the wheel can
>>>>>>>>>>>>> support loads only to the point where its spokes become loose. at
>>>>>>>>>>>>> this point the wheel will collapse." jobst brandt. "the book". 3rd
>>>>>>>>>>>>> edition.
>>>>>>>>>>>> Would "jim beam's" wheel with missing spokes collapse if ridden? If so,
>>>>>>>>>>>> JB is right (for all practical purposes) and jb is wrong.
>>>>>>>>>>>>
>>>>>>>>>>> i've ridden a slack spoked wheel so see if it works. and it does. and
>>>>>>>>>>> you can google this group for my experience with a friend's slack spoked
>>>>>>>>>>> mtb wheel. you should try it too. your only problem is spoke nipples
>>>>>>>>>>> unscrewing.
>>>>>>>>>> So, once again the photograph you offered as proof turns out to be no sort
>>>>>>>>>> of proof at all.
>>>>>>>>> so you're saying that pic is a fabrication? it's holding my full body
>>>>>>>>> weight. i am the heaviest thing in my house. what more do you want
>>>>>>>>> gary?
>>>>>>>> As I've said elsewhere, what I would expect before taking your claims
>>>>>>>> seriously is an experiment that actually tests Jobst's claims. That would
>>>>>>>> require subjecting your wheel to a significant side load. You haven't done
>>>>>>>> that.
>>>>>>>>
>>>>>>>>> of course, you /could/ bother to replicate my experiment rather
>>>>>>>>> than simply bellyache, but that's not an armchair exercise.
>>>>>>>> Replicate? You haven't done an experiment that tests Jobst's claims.
>>>>>>>> What's to replicate? And no, I won't be the one to do the initial
>>>>>>>> experiment for you. I don't risk expensive equipment on the word of an
>>>>>>>> anonymous internet crank.
>>>>>>> hmmm. i put my money where my mouth is and i post the results. what do
>>>>>>> you do? [other than just bleat from the sidelines of course.]
>>>>>>>
>>>>>> In other words, you conducted an irrelevant experiment that doesn't
>>>>>> address the issue of side loads, but you want an "A" for effort anyway.
>>>>> eh? evidence contradicting an argument based on fundamental
>>>>> misunderstanding is "irrelevant"?
>>>>>
>>>>> good luck to you out there in the real world gary - you need it!
>>>>>
>>>>>
>>>>>>> and that's a rhetorical question.
>>>> Is your position that side loads play no role in wheel failures?
>>>
>>> no, my position is that you don't understand enough to be even asking
>>> that question!
>>
>> How do side loads figure in your explanation of wheel failure? (Please
>> spare me the ad hominem arguments; my understanding or lack of it
>> is irrelevant to whether you can answer a perfectly straightforward
>> question.)
>>
>> Also, since you agree that side loads do play a part in wheel failures,
>> why didn't you subject your experimental wheel to a side load?
>
> what part of "i've ridden a slack spoked wheel so see if it works. and
> it does." is unclear?
You said you didn't ride the experimental wheel in the photograph because
you didn't want the tensiometer to fall off. I take it that you're now
referring to some other incident in which you rode a slack wheel. That at
least is some progress -- you've implicitly admitted that the experiment
you photographed is irrelevant to the issue of side loads. In order to
answer my question, you had to appeal to evidence outside of the
experiment in the photograph.
When you rode the slack spoked wheel, did you subject it to significant
side loads? Please explain what they were.
Also, please answer my question about what place side loads play in your
theoretical account of wheel failure.
|
| |
Date: 21 Jul 2007 10:39:04
From: Ron Ruff
Subject: Re: spoke tension
|
On Jul 18, 7:02 am, jim beam <spamvor...@bad.example.net > wrote:
> how about you address the point of the posting: "...the wheel can
> support loads only to the point where its spokes become loose. at this
> point the wheel will collapse." jobst brandt. "the book". 3rd edition.
Maybe an exaggeration... but close to the truth. When spokes become
slack they no longer provide support to the rim, so the rim is sort of
on it's own. It's stiffness and strength and resistance to buckling
drops a lot.
|
| | |
Date: 21 Jul 2007 10:05:43
From: jim beam
Subject: Re: spoke tension
|
Ron Ruff wrote:
> On Jul 18, 7:02 am, jim beam <spamvor...@bad.example.net> wrote:
>> how about you address the point of the posting: "...the wheel can
>> support loads only to the point where its spokes become loose. at this
>> point the wheel will collapse." jobst brandt. "the book". 3rd edition.
>
> Maybe an exaggeration... but close to the truth. When spokes become
> slack they no longer provide support to the rim, so the rim is sort of
> on it's own. It's stiffness and strength and resistance to buckling
> drops a lot.
>
>
finally, someone that gets it!
indeed, spokes /do/ support the rim. but the support of the spokes
relies on tension. that tension is "borrowed" from the rim. and
tension in excess of that required to prevent spoke slackening comes at
the cost of bringing the rim closer to yield than is necessary, /and/ at
the cost of increasing fatigue propensity.
and wheel strength does not increase as spoke tension increases. and a
wheel will not collapse because a few spokes are slack.
|
| | | |
Date: 21 Jul 2007 15:55:15
From: Peter Cole
Subject: Re: spoke tension
|
jim beam wrote:
> Ron Ruff wrote:
>> Maybe an exaggeration... but close to the truth. When spokes become
>> slack they no longer provide support to the rim, so the rim is sort of
>> on it's own. It's stiffness and strength and resistance to buckling
>> drops a lot.
>>
>>
> finally, someone that gets it!
>
> indeed, spokes /do/ support the rim. but the support of the spokes
> relies on tension. that tension is "borrowed" from the rim. and
> tension in excess of that required to prevent spoke slackening comes at
> the cost of bringing the rim closer to yield than is necessary, /and/ at
> the cost of increasing fatigue propensity.
>
> and wheel strength does not increase as spoke tension increases. and a
> wheel will not collapse because a few spokes are slack.
What's to get? This (as usual) is a tempest in a teapot. Everyone
realizes that a wheel with too loose spokes is weak and everyone
realizes that a wheel with too tight spokes is weak (will taco if you
breathe on it). Therefore, in between there is some ideal spoke tension.
You may set this tension with a tensiometer per the maker's spec., or
you can use Jobst's method *if* you don't have a tensiometer and you
have rims like the ones he mentions.
You tediously go on & on about this as if Jobst doesn't believe in
tensiometers (he did design one) or recommends the alternative approach
in an unqualified way (which he didn't).
With regard to strength, there are at least 2 common modes of wheel
failure: flat spotting and taco'ing. You don't specify which you're
talking about.
For spoke tension to affect flat spotting by "borrowing" from rim
compression, you'd have to calculate the static compressive stress and
compare that to yield stress. If static was 10% of yield, then a 20%
change in spoke tension would only translate into a 2% yield difference
(presuming wheel yield was initiated by compressive yield, something
you'd also have to prove). For spoke tension to be a factor, static rim
compressive stress would have to be a significant fraction of yield. I
doubt that, but if you have the numbers, I'm all ears.
To know static compressive stress, you'd have to know static force (in
Jobst's book) and rim cross section area. You have those, right?
For taco failures things get a lot more complicated. I'm not aware of an
out of plane loading model that would apply, the radial model is
complicated enough. But if you have insight, please share.
|
| | | | |
Date: 21 Jul 2007 13:15:17
From: jim beam
Subject: Re: spoke tension
|
Peter Cole wrote:
> jim beam wrote:
>> Ron Ruff wrote:
>
>>> Maybe an exaggeration... but close to the truth. When spokes become
>>> slack they no longer provide support to the rim, so the rim is sort of
>>> on it's own. It's stiffness and strength and resistance to buckling
>>> drops a lot.
>>>
>>>
>> finally, someone that gets it!
>>
>> indeed, spokes /do/ support the rim. but the support of the spokes
>> relies on tension. that tension is "borrowed" from the rim. and
>> tension in excess of that required to prevent spoke slackening comes
>> at the cost of bringing the rim closer to yield than is necessary,
>> /and/ at the cost of increasing fatigue propensity.
>>
>> and wheel strength does not increase as spoke tension increases. and
>> a wheel will not collapse because a few spokes are slack.
>
> What's to get? This (as usual) is a tempest in a teapot. Everyone
> realizes that a wheel with too loose spokes is weak and everyone
> realizes that a wheel with too tight spokes is weak (will taco if you
> breathe on it). Therefore, in between there is some ideal spoke tension.
like "stress relief", the practice is qualitatively right, but the
theory is way off base. you /do/ indeed need sufficient spoke tension
for a trouble free wheel, but the reason is to avoid spoke nipples
unscrewing and spoke elbow fatigue. neither are static wheel strength.
>
> You may set this tension with a tensiometer per the maker's spec., or
> you can use Jobst's method *if* you don't have a tensiometer and you
> have rims like the ones he mentions.
maybe for an old fashioned rim, but for a modern higher profile
[stiffer] rim, that method gives spoke tension too high which in turn
causes rims to crack.
>
> You tediously go on & on about this as if Jobst doesn't believe in
> tensiometers (he did design one)
because we do have his word for it. he's said repeatedly that you don't
need a tensiometer, simply use spoke tension "as high as the rim can bear".
and he didn't finish the math on his tensiometer. look at the formula
in his book. he thinks that tensiometer readings are unaffected by
spoke stiffness - which is untrue.
> or recommends the alternative approach
> in an unqualified way (which he didn't).
>
> With regard to strength, there are at least 2 common modes of wheel
> failure: flat spotting and taco'ing. You don't specify which you're
> talking about.
either. a rim yield when any point in it exceeds the requite stress.
the metal doesn't care whether that stress is from application or
superposition. when high enough, it yields. tension or compression.
end of story.
>
> For spoke tension to affect flat spotting by "borrowing" from rim
> compression, you'd have to calculate the static compressive stress and
> compare that to yield stress. If static was 10% of yield, then a 20%
> change in spoke tension would only translate into a 2% yield difference
> (presuming wheel yield was initiated by compressive yield, something
> you'd also have to prove). For spoke tension to be a factor, static rim
> compressive stress would have to be a significant fraction of yield. I
> doubt that, but if you have the numbers, I'm all ears.
buckling is close to yield, and spoke tension "as high as the rim can
bear" is that limit.
>
> To know static compressive stress, you'd have to know static force (in
> Jobst's book) and rim cross section area. You have those, right?
what good will knowing the force be if you don't know the strength of
the materials?
>
> For taco failures things get a lot more complicated. I'm not aware of an
> out of plane loading model that would apply, the radial model is
> complicated enough. But if you have insight, please share.
don't seek refuge in complexity. each element is simple.
here's the bottom line: the calculations in the book compute load.
that's all fine and dandy, but load doesn't tell you a damned thing
about strength. this is the point you keep missing and which jobst
doesn't address.
|
| | | | | |
Date: 21 Jul 2007 18:32:54
From: Peter Cole
Subject: Re: spoke tension
|
jim beam wrote:
<snipped same old crap >
> here's the bottom line: the calculations in the book compute load.
> that's all fine and dandy, but load doesn't tell you a damned thing
> about strength. this is the point you keep missing and which jobst
> doesn't address.
Bottom line is you don't have the numbers.
|
| | | | | | |
Date: 21 Jul 2007 13:45:36
From: jim beam
Subject: Re: spoke tension
|
Peter Cole wrote:
> jim beam wrote:
> <snipped same old crap>
>
>> here's the bottom line: the calculations in the book compute load.
>> that's all fine and dandy, but load doesn't tell you a damned thing
>> about strength. this is the point you keep missing and which jobst
>> doesn't address.
>
> Bottom line is you don't have the numbers.
>
bottom line, you're still missing the point. you show me how a load
calc demonstrates strength [or better yet, how increasing load increases
strength], /then/ we can talk numbers.
|
| | | | | | | |
Date: 21 Jul 2007 19:01:36
From: Peter Cole
Subject: Re: spoke tension
|
jim beam wrote:
> Peter Cole wrote:
>> jim beam wrote:
>> <snipped same old crap>
>>
>>> here's the bottom line: the calculations in the book compute load.
>>> that's all fine and dandy, but load doesn't tell you a damned thing
>>> about strength. this is the point you keep missing and which jobst
>>> doesn't address.
>>
>> Bottom line is you don't have the numbers.
>>
> bottom line, you're still missing the point. you show me how a load
> calc demonstrates strength [or better yet, how increasing load increases
> strength], /then/ we can talk numbers.
Sorry, I have no interest in that.
|
| | | | | | | | |
Date: 21 Jul 2007 13:48:40
From: jim beam
Subject: Re: spoke tension
|
Peter Cole wrote:
> jim beam wrote:
>> Peter Cole wrote:
>>> jim beam wrote:
>>> <snipped same old crap>
>>>
>>>> here's the bottom line: the calculations in the book compute load.
>>>> that's all fine and dandy, but load doesn't tell you a damned thing
>>>> about strength. this is the point you keep missing and which jobst
>>>> doesn't address.
>>>
>>> Bottom line is you don't have the numbers.
>>>
>> bottom line, you're still missing the point. you show me how a load
>> calc demonstrates strength [or better yet, how increasing load
>> increases strength], /then/ we can talk numbers.
>
> Sorry, I have no interest in that.
evidently. shame.
|
| | | | |
Date: 21 Jul 2007 20:24:22
From:
Subject: Re: spoke tension
|
Peter Cole writes:
>>> Maybe an exaggeration... but close to the truth. When spokes
>>> become slack they no longer provide support to the rim, so the rim
>>> is sort of on it's own. It's stiffness and strength and
>>> resistance to buckling drops a lot.
>> finally, someone that gets it!
>> indeed, spokes /do/ support the rim. but the support of the spokes
>> relies on tension. that tension is "borrowed" from the rim. and
>> tension in excess of that required to prevent spoke slackening
>> comes at the cost of bringing the rim closer to yield than is
>> necessary, /and/ at the cost of increasing fatigue propensity.
>> and wheel strength does not increase as spoke tension increases.
>> and a wheel will not collapse because a few spokes are slack.
> What's to get? This (as usual) is a tempest in a teapot. Everyone
> realizes that a wheel with too loose spokes is weak and everyone
> realizes that a wheel with too tight spokes is weak (will taco if
> you breathe on it). Therefore, in between there is some ideal spoke
> tension.
> You may set this tension with a tensiometer per the maker's spec.,
> or you can use Jobst's method *if* you don't have a tensiometer and
> you have rims like the ones he mentions.
> You tediously go on & on about this as if Jobst doesn't believe in
> tensiometers (he did design one) or recommends the alternative
> approach in an unqualified way (which he didn't).
> With regard to strength, there are at least 2 common modes of wheel
> failure: flat spotting and taco'ing. You don't specify which you're
> talking about.
> For spoke tension to affect flat spotting by "borrowing" from rim
> compression, you'd have to calculate the static compressive stress
> and compare that to yield stress. If static was 10% of yield, then
> a 20% change in spoke tension would only translate into a 2% yield
> difference (presuming wheel yield was initiated by compressive
> yield, something you'd also have to prove). For spoke tension to be
> a factor, static rim compressive stress would have to be a
> significant fraction of yield. I doubt that, but if you have the
> numbers, I'm all ears.
Flat spots are caused typically by landing on a relatively (to the
tire cross section) smooth place, like coming down onto smooth
pavement from too high a jump, or hitting a v-groove (open culvert
type) at too high a speed. If this doesn't bottom the tire, the bead
of the rim will not be damaged but the rim, as a bridge, will yield
and not return from the flattened condition entirely.
Considering how the wheel supports loads, this is the standard way
taken beyond the limit of rim strength. Unfortunately, these limiting
conditions are no longer addressed in road rims today so we ride on
fragile, low spoke count rims that crack at the suggestion of use and
get flat spots readily.
> To know static compressive stress, you'd have to know static force
> (in Jobst's book) and rim cross section area. You have those,
> right?
The limit of tension for good rims was the tension at which the
compressive force caused buckling; the tension at which the rim begins
to pretzel. This effect is not sudden or large, the rim being held in
line by the spokes that are not near yield and have a large elastic
modulus. The amount of yield for this to be visible is microscopic,
the ratio of bending to length change being enormous as most people
have gathered from the coat hanger test. You can easily bend a coat
hanger manually but you can't even begin to stretch it by hand.
> For taco failures things get a lot more complicated. I'm not aware
> of an out of plane loading model that would apply, the radial model
> is complicated enough. But if you have insight, please share.
To do this loosen the spokes to near zero tension and see how much
more the wheel deflects when a weight is hung on it, as shown in the
tying and soldering defection test in "thew Bicycle Wheel".
Jobst Brandt
|
| |
Date: 21 Jul 2007 12:13:03
From: Gary Young
Subject: Re: spoke tension
|
On Sat, 21 Jul 2007 09:24:11 -0700, jim beam wrote:
> Gary Young wrote:
>> On Sat, 21 Jul 2007 09:03:50 -0700, jim beam wrote:
>>
>>> Gary Young wrote:
>>>> On Fri, 20 Jul 2007 18:53:12 -0700, jim beam wrote:
>>>>
>>>>> Gary Young wrote:
>>>>>> On Thu, 19 Jul 2007 05:54:37 -0700, jim beam wrote:
>>>>>>
>>>>>>> Gary Young wrote:
>>>>>>>> On Wed, 18 Jul 2007 21:43:17 -0700, jim beam wrote:
>>>>>>>>
>>>>>>>>> Johnny Sunset aka Tom Sherman wrote:
>>>>>>>>>> "jim beam" ? wrote:
>>>>>>>>>>> Johnny Sunset aka Tom Sherman wrote:
>>>>>>>>>>>> "jim beam" ? wrote:
>>>>>>>>>>>>> ...
>>>>>>>>>>>>> in your book, you also argue that rims collapse as soon as spokes go
>>>>>>>>>>>>> slack go slack....
>>>>>>>>>>>>> http://www.flickr.com/photos/38636024@N00/417157612/
>>>>>>>>>>>> How far did you ride on that wheel?
>>>>>>>>>>>>
>>>>>>>>>>> as far as i could without the tensiometer falling off... wise guy.
>>>>>>>>>>>
>>>>>>>>>>> how about you address the point of the posting: "...the wheel can
>>>>>>>>>>> support loads only to the point where its spokes become loose. at
>>>>>>>>>>> this point the wheel will collapse." jobst brandt. "the book". 3rd
>>>>>>>>>>> edition.
>>>>>>>>>> Would "jim beam's" wheel with missing spokes collapse if ridden? If so,
>>>>>>>>>> JB is right (for all practical purposes) and jb is wrong.
>>>>>>>>>>
>>>>>>>>> i've ridden a slack spoked wheel so see if it works. and it does. and
>>>>>>>>> you can google this group for my experience with a friend's slack spoked
>>>>>>>>> mtb wheel. you should try it too. your only problem is spoke nipples
>>>>>>>>> unscrewing.
>>>>>>>> So, once again the photograph you offered as proof turns out to be no sort
>>>>>>>> of proof at all.
>>>>>>> so you're saying that pic is a fabrication? it's holding my full body
>>>>>>> weight. i am the heaviest thing in my house. what more do you want
>>>>>>> gary?
>>>>>> As I've said elsewhere, what I would expect before taking your claims
>>>>>> seriously is an experiment that actually tests Jobst's claims. That would
>>>>>> require subjecting your wheel to a significant side load. You haven't done
>>>>>> that.
>>>>>>
>>>>>>> of course, you /could/ bother to replicate my experiment rather
>>>>>>> than simply bellyache, but that's not an armchair exercise.
>>>>>> Replicate? You haven't done an experiment that tests Jobst's claims.
>>>>>> What's to replicate? And no, I won't be the one to do the initial
>>>>>> experiment for you. I don't risk expensive equipment on the word of an
>>>>>> anonymous internet crank.
>>>>> hmmm. i put my money where my mouth is and i post the results. what do
>>>>> you do? [other than just bleat from the sidelines of course.]
>>>>>
>>>> In other words, you conducted an irrelevant experiment that doesn't
>>>> address the issue of side loads, but you want an "A" for effort anyway.
>>> eh? evidence contradicting an argument based on fundamental
>>> misunderstanding is "irrelevant"?
>>>
>>> good luck to you out there in the real world gary - you need it!
>>>
>>>
>>>>> and that's a rhetorical question.
>>
>> Is your position that side loads play no role in wheel failures?
>
>
> no, my position is that you don't understand enough to be even asking
> that question!
How do side loads figure in your explanation of wheel failure? (Please
spare me the ad hominem arguments; my understanding or lack of it
is irrelevant to whether you can answer a perfectly straightforward
question.)
Also, since you agree that side loads do play a part in wheel failures,
why didn't you subject your experimental wheel to a side load?
|
| | |
Date: 21 Jul 2007 09:38:15
From: jim beam
Subject: Re: spoke tension
|
Gary Young wrote:
> On Sat, 21 Jul 2007 09:24:11 -0700, jim beam wrote:
>
>> Gary Young wrote:
>>> On Sat, 21 Jul 2007 09:03:50 -0700, jim beam wrote:
>>>
>>>> Gary Young wrote:
>>>>> On Fri, 20 Jul 2007 18:53:12 -0700, jim beam wrote:
>>>>>
>>>>>> Gary Young wrote:
>>>>>>> On Thu, 19 Jul 2007 05:54:37 -0700, jim beam wrote:
>>>>>>>
>>>>>>>> Gary Young wrote:
>>>>>>>>> On Wed, 18 Jul 2007 21:43:17 -0700, jim beam wrote:
>>>>>>>>>
>>>>>>>>>> Johnny Sunset aka Tom Sherman wrote:
>>>>>>>>>>> "jim beam" ? wrote:
>>>>>>>>>>>> Johnny Sunset aka Tom Sherman wrote:
>>>>>>>>>>>>> "jim beam" ? wrote:
>>>>>>>>>>>>>> ...
>>>>>>>>>>>>>> in your book, you also argue that rims collapse as soon as spokes go
>>>>>>>>>>>>>> slack go slack....
>>>>>>>>>>>>>> http://www.flickr.com/photos/38636024@N00/417157612/
>>>>>>>>>>>>> How far did you ride on that wheel?
>>>>>>>>>>>>>
>>>>>>>>>>>> as far as i could without the tensiometer falling off... wise guy.
>>>>>>>>>>>>
>>>>>>>>>>>> how about you address the point of the posting: "...the wheel can
>>>>>>>>>>>> support loads only to the point where its spokes become loose. at
>>>>>>>>>>>> this point the wheel will collapse." jobst brandt. "the book". 3rd
>>>>>>>>>>>> edition.
>>>>>>>>>>> Would "jim beam's" wheel with missing spokes collapse if ridden? If so,
>>>>>>>>>>> JB is right (for all practical purposes) and jb is wrong.
>>>>>>>>>>>
>>>>>>>>>> i've ridden a slack spoked wheel so see if it works. and it does. and
>>>>>>>>>> you can google this group for my experience with a friend's slack spoked
>>>>>>>>>> mtb wheel. you should try it too. your only problem is spoke nipples
>>>>>>>>>> unscrewing.
>>>>>>>>> So, once again the photograph you offered as proof turns out to be no sort
>>>>>>>>> of proof at all.
>>>>>>>> so you're saying that pic is a fabrication? it's holding my full body
>>>>>>>> weight. i am the heaviest thing in my house. what more do you want
>>>>>>>> gary?
>>>>>>> As I've said elsewhere, what I would expect before taking your claims
>>>>>>> seriously is an experiment that actually tests Jobst's claims. That would
>>>>>>> require subjecting your wheel to a significant side load. You haven't done
>>>>>>> that.
>>>>>>>
>>>>>>>> of course, you /could/ bother to replicate my experiment rather
>>>>>>>> than simply bellyache, but that's not an armchair exercise.
>>>>>>> Replicate? You haven't done an experiment that tests Jobst's claims.
>>>>>>> What's to replicate? And no, I won't be the one to do the initial
>>>>>>> experiment for you. I don't risk expensive equipment on the word of an
>>>>>>> anonymous internet crank.
>>>>>> hmmm. i put my money where my mouth is and i post the results. what do
>>>>>> you do? [other than just bleat from the sidelines of course.]
>>>>>>
>>>>> In other words, you conducted an irrelevant experiment that doesn't
>>>>> address the issue of side loads, but you want an "A" for effort anyway.
>>>> eh? evidence contradicting an argument based on fundamental
>>>> misunderstanding is "irrelevant"?
>>>>
>>>> good luck to you out there in the real world gary - you need it!
>>>>
>>>>
>>>>>> and that's a rhetorical question.
>>> Is your position that side loads play no role in wheel failures?
>>
>> no, my position is that you don't understand enough to be even asking
>> that question!
>
> How do side loads figure in your explanation of wheel failure? (Please
> spare me the ad hominem arguments; my understanding or lack of it
> is irrelevant to whether you can answer a perfectly straightforward
> question.)
>
> Also, since you agree that side loads do play a part in wheel failures,
> why didn't you subject your experimental wheel to a side load?
what part of "i've ridden a slack spoked wheel so see if it works. and
it does." is unclear?
|
| |
Date: 21 Jul 2007 11:55:27
From: Gary Young
Subject: Re: spoke tension
|
On Sat, 21 Jul 2007 09:03:50 -0700, jim beam wrote:
> Gary Young wrote:
>> On Fri, 20 Jul 2007 18:53:12 -0700, jim beam wrote:
>>
>>> Gary Young wrote:
>>>> On Thu, 19 Jul 2007 05:54:37 -0700, jim beam wrote:
>>>>
>>>>> Gary Young wrote:
>>>>>> On Wed, 18 Jul 2007 21:43:17 -0700, jim beam wrote:
>>>>>>
>>>>>>> Johnny Sunset aka Tom Sherman wrote:
>>>>>>>> "jim beam" ? wrote:
>>>>>>>>> Johnny Sunset aka Tom Sherman wrote:
>>>>>>>>>> "jim beam" ? wrote:
>>>>>>>>>>> ...
>>>>>>>>>>> in your book, you also argue that rims collapse as soon as spokes go
>>>>>>>>>>> slack go slack....
>>>>>>>>>>> http://www.flickr.com/photos/38636024@N00/417157612/
>>>>>>>>>> How far did you ride on that wheel?
>>>>>>>>>>
>>>>>>>>> as far as i could without the tensiometer falling off... wise guy.
>>>>>>>>>
>>>>>>>>> how about you address the point of the posting: "...the wheel can
>>>>>>>>> support loads only to the point where its spokes become loose. at
>>>>>>>>> this point the wheel will collapse." jobst brandt. "the book". 3rd
>>>>>>>>> edition.
>>>>>>>> Would "jim beam's" wheel with missing spokes collapse if ridden? If so,
>>>>>>>> JB is right (for all practical purposes) and jb is wrong.
>>>>>>>>
>>>>>>> i've ridden a slack spoked wheel so see if it works. and it does. and
>>>>>>> you can google this group for my experience with a friend's slack spoked
>>>>>>> mtb wheel. you should try it too. your only problem is spoke nipples
>>>>>>> unscrewing.
>>>>>> So, once again the photograph you offered as proof turns out to be no sort
>>>>>> of proof at all.
>>>>> so you're saying that pic is a fabrication? it's holding my full body
>>>>> weight. i am the heaviest thing in my house. what more do you want
>>>>> gary?
>>>> As I've said elsewhere, what I would expect before taking your claims
>>>> seriously is an experiment that actually tests Jobst's claims. That would
>>>> require subjecting your wheel to a significant side load. You haven't done
>>>> that.
>>>>
>>>>> of course, you /could/ bother to replicate my experiment rather
>>>>> than simply bellyache, but that's not an armchair exercise.
>>>> Replicate? You haven't done an experiment that tests Jobst's claims.
>>>> What's to replicate? And no, I won't be the one to do the initial
>>>> experiment for you. I don't risk expensive equipment on the word of an
>>>> anonymous internet crank.
>>> hmmm. i put my money where my mouth is and i post the results. what do
>>> you do? [other than just bleat from the sidelines of course.]
>>>
>>
>> In other words, you conducted an irrelevant experiment that doesn't
>> address the issue of side loads, but you want an "A" for effort anyway.
>
> eh? evidence contradicting an argument based on fundamental
> misunderstanding is "irrelevant"?
>
> good luck to you out there in the real world gary - you need it!
>
>
>>
>>> and that's a rhetorical question.
Is your position that side loads play no role in wheel failures?
|
| | |
Date: 21 Jul 2007 09:24:11
From: jim beam
Subject: Re: spoke tension
|
Gary Young wrote:
> On Sat, 21 Jul 2007 09:03:50 -0700, jim beam wrote:
>
>> Gary Young wrote:
>>> On Fri, 20 Jul 2007 18:53:12 -0700, jim beam wrote:
>>>
>>>> Gary Young wrote:
>>>>> On Thu, 19 Jul 2007 05:54:37 -0700, jim beam wrote:
>>>>>
>>>>>> Gary Young wrote:
>>>>>>> On Wed, 18 Jul 2007 21:43:17 -0700, jim beam wrote:
>>>>>>>
>>>>>>>> Johnny Sunset aka Tom Sherman wrote:
>>>>>>>>> "jim beam" ? wrote:
>>>>>>>>>> Johnny Sunset aka Tom Sherman wrote:
>>>>>>>>>>> "jim beam" ? wrote:
>>>>>>>>>>>> ...
>>>>>>>>>>>> in your book, you also argue that rims collapse as soon as spokes go
>>>>>>>>>>>> slack go slack....
>>>>>>>>>>>> http://www.flickr.com/photos/38636024@N00/417157612/
>>>>>>>>>>> How far did you ride on that wheel?
>>>>>>>>>>>
>>>>>>>>>> as far as i could without the tensiometer falling off... wise guy.
>>>>>>>>>>
>>>>>>>>>> how about you address the point of the posting: "...the wheel can
>>>>>>>>>> support loads only to the point where its spokes become loose. at
>>>>>>>>>> this point the wheel will collapse." jobst brandt. "the book". 3rd
>>>>>>>>>> edition.
>>>>>>>>> Would "jim beam's" wheel with missing spokes collapse if ridden? If so,
>>>>>>>>> JB is right (for all practical purposes) and jb is wrong.
>>>>>>>>>
>>>>>>>> i've ridden a slack spoked wheel so see if it works. and it does. and
>>>>>>>> you can google this group for my experience with a friend's slack spoked
>>>>>>>> mtb wheel. you should try it too. your only problem is spoke nipples
>>>>>>>> unscrewing.
>>>>>>> So, once again the photograph you offered as proof turns out to be no sort
>>>>>>> of proof at all.
>>>>>> so you're saying that pic is a fabrication? it's holding my full body
>>>>>> weight. i am the heaviest thing in my house. what more do you want
>>>>>> gary?
>>>>> As I've said elsewhere, what I would expect before taking your claims
>>>>> seriously is an experiment that actually tests Jobst's claims. That would
>>>>> require subjecting your wheel to a significant side load. You haven't done
>>>>> that.
>>>>>
>>>>>> of course, you /could/ bother to replicate my experiment rather
>>>>>> than simply bellyache, but that's not an armchair exercise.
>>>>> Replicate? You haven't done an experiment that tests Jobst's claims.
>>>>> What's to replicate? And no, I won't be the one to do the initial
>>>>> experiment for you. I don't risk expensive equipment on the word of an
>>>>> anonymous internet crank.
>>>> hmmm. i put my money where my mouth is and i post the results. what do
>>>> you do? [other than just bleat from the sidelines of course.]
>>>>
>>> In other words, you conducted an irrelevant experiment that doesn't
>>> address the issue of side loads, but you want an "A" for effort anyway.
>> eh? evidence contradicting an argument based on fundamental
>> misunderstanding is "irrelevant"?
>>
>> good luck to you out there in the real world gary - you need it!
>>
>>
>>>> and that's a rhetorical question.
>
> Is your position that side loads play no role in wheel failures?
no, my position is that you don't understand enough to be even asking
that question!
|
| |
Date: 21 Jul 2007 11:01:48
From: Gary Young
Subject: Re: spoke tension
|
On Fri, 20 Jul 2007 18:53:12 -0700, jim beam wrote:
> Gary Young wrote:
>> On Thu, 19 Jul 2007 05:54:37 -0700, jim beam wrote:
>>
>>> Gary Young wrote:
>>>> On Wed, 18 Jul 2007 21:43:17 -0700, jim beam wrote:
>>>>
>>>>> Johnny Sunset aka Tom Sherman wrote:
>>>>>> "jim beam" ? wrote:
>>>>>>> Johnny Sunset aka Tom Sherman wrote:
>>>>>>>> "jim beam" ? wrote:
>>>>>>>>> ...
>>>>>>>>> in your book, you also argue that rims collapse as soon as spokes go
>>>>>>>>> slack go slack....
>>>>>>>>> http://www.flickr.com/photos/38636024@N00/417157612/
>>>>>>>> How far did you ride on that wheel?
>>>>>>>>
>>>>>>> as far as i could without the tensiometer falling off... wise guy.
>>>>>>>
>>>>>>> how about you address the point of the posting: "...the wheel can
>>>>>>> support loads only to the point where its spokes become loose. at
>>>>>>> this point the wheel will collapse." jobst brandt. "the book". 3rd
>>>>>>> edition.
>>>>>> Would "jim beam's" wheel with missing spokes collapse if ridden? If so,
>>>>>> JB is right (for all practical purposes) and jb is wrong.
>>>>>>
>>>>> i've ridden a slack spoked wheel so see if it works. and it does. and
>>>>> you can google this group for my experience with a friend's slack spoked
>>>>> mtb wheel. you should try it too. your only problem is spoke nipples
>>>>> unscrewing.
>>>> So, once again the photograph you offered as proof turns out to be no sort
>>>> of proof at all.
>>> so you're saying that pic is a fabrication? it's holding my full body
>>> weight. i am the heaviest thing in my house. what more do you want
>>> gary?
>>
>> As I've said elsewhere, what I would expect before taking your claims
>> seriously is an experiment that actually tests Jobst's claims. That would
>> require subjecting your wheel to a significant side load. You haven't done
>> that.
>>
>>> of course, you /could/ bother to replicate my experiment rather
>>> than simply bellyache, but that's not an armchair exercise.
>>
>> Replicate? You haven't done an experiment that tests Jobst's claims.
>> What's to replicate? And no, I won't be the one to do the initial
>> experiment for you. I don't risk expensive equipment on the word of an
>> anonymous internet crank.
>
> hmmm. i put my money where my mouth is and i post the results. what do
> you do? [other than just bleat from the sidelines of course.]
>
In other words, you conducted an irrelevant experiment that doesn't
address the issue of side loads, but you want an "A" for effort anyway.
> and that's a rhetorical question.
|
| | |
Date: 21 Jul 2007 09:03:50
From: jim beam
Subject: Re: spoke tension
|
Gary Young wrote:
> On Fri, 20 Jul 2007 18:53:12 -0700, jim beam wrote:
>
>> Gary Young wrote:
>>> On Thu, 19 Jul 2007 05:54:37 -0700, jim beam wrote:
>>>
>>>> Gary Young wrote:
>>>>> On Wed, 18 Jul 2007 21:43:17 -0700, jim beam wrote:
>>>>>
>>>>>> Johnny Sunset aka Tom Sherman wrote:
>>>>>>> "jim beam" ? wrote:
>>>>>>>> Johnny Sunset aka Tom Sherman wrote:
>>>>>>>>> "jim beam" ? wrote:
>>>>>>>>>> ...
>>>>>>>>>> in your book, you also argue that rims collapse as soon as spokes go
>>>>>>>>>> slack go slack....
>>>>>>>>>> http://www.flickr.com/photos/38636024@N00/417157612/
>>>>>>>>> How far did you ride on that wheel?
>>>>>>>>>
>>>>>>>> as far as i could without the tensiometer falling off... wise guy.
>>>>>>>>
>>>>>>>> how about you address the point of the posting: "...the wheel can
>>>>>>>> support loads only to the point where its spokes become loose. at
>>>>>>>> this point the wheel will collapse." jobst brandt. "the book". 3rd
>>>>>>>> edition.
>>>>>>> Would "jim beam's" wheel with missing spokes collapse if ridden? If so,
>>>>>>> JB is right (for all practical purposes) and jb is wrong.
>>>>>>>
>>>>>> i've ridden a slack spoked wheel so see if it works. and it does. and
>>>>>> you can google this group for my experience with a friend's slack spoked
>>>>>> mtb wheel. you should try it too. your only problem is spoke nipples
>>>>>> unscrewing.
>>>>> So, once again the photograph you offered as proof turns out to be no sort
>>>>> of proof at all.
>>>> so you're saying that pic is a fabrication? it's holding my full body
>>>> weight. i am the heaviest thing in my house. what more do you want
>>>> gary?
>>> As I've said elsewhere, what I would expect before taking your claims
>>> seriously is an experiment that actually tests Jobst's claims. That would
>>> require subjecting your wheel to a significant side load. You haven't done
>>> that.
>>>
>>>> of course, you /could/ bother to replicate my experiment rather
>>>> than simply bellyache, but that's not an armchair exercise.
>>> Replicate? You haven't done an experiment that tests Jobst's claims.
>>> What's to replicate? And no, I won't be the one to do the initial
>>> experiment for you. I don't risk expensive equipment on the word of an
>>> anonymous internet crank.
>> hmmm. i put my money where my mouth is and i post the results. what do
>> you do? [other than just bleat from the sidelines of course.]
>>
>
> In other words, you conducted an irrelevant experiment that doesn't
> address the issue of side loads, but you want an "A" for effort anyway.
eh? evidence contradicting an argument based on fundamental
misunderstanding is "irrelevant"?
good luck to you out there in the real world gary - you need it!
>
>> and that's a rhetorical question.
|
| |
Date: 19 Jul 2007 17:32:28
From: Jay Beattie
Subject: Re: spoke tension
|
On Jul 18, 8:57 pm, nickzajchow...@gmail.com wrote:
> On Jul 16, 10:19 pm, mark <markfel...@earthlink.net> wrote:
>
> > Could someone recommend the proper spoke tension for a rear wheel built
> > with a Velocity Aerohead OC rim?
>
> > TIA,
>
> > mark
> >From Velocity USA:
>
> "We aim for around 105-115 kgf for front wheels, 110-120 kgf for rear
> wheels. This applies to all of our rims."
Hey, that's the number I came up with through trial and error. 100 kgf
was too low to keep them true (for a heavy rider like me). And they
will crack at the spoke holes above 120 kgf. -- Jay Beattie.
|
| |
Date: 19 Jul 2007 08:28:34
From: Gary Young
Subject: Re: spoke tension
|
On Thu, 19 Jul 2007 05:54:37 -0700, jim beam wrote:
> Gary Young wrote:
>> On Wed, 18 Jul 2007 21:43:17 -0700, jim beam wrote:
>>
>>> Johnny Sunset aka Tom Sherman wrote:
>>>> "jim beam" ? wrote:
>>>>> Johnny Sunset aka Tom Sherman wrote:
>>>>>> "jim beam" ? wrote:
>>>>>>> ...
>>>>>>> in your book, you also argue that rims collapse as soon as spokes go
>>>>>>> slack go slack....
>>>>>>> http://www.flickr.com/photos/38636024@N00/417157612/
>>>>>> How far did you ride on that wheel?
>>>>>>
>>>>> as far as i could without the tensiometer falling off... wise guy.
>>>>>
>>>>> how about you address the point of the posting: "...the wheel can
>>>>> support loads only to the point where its spokes become loose. at
>>>>> this point the wheel will collapse." jobst brandt. "the book". 3rd
>>>>> edition.
>>>> Would "jim beam's" wheel with missing spokes collapse if ridden? If so,
>>>> JB is right (for all practical purposes) and jb is wrong.
>>>>
>>> i've ridden a slack spoked wheel so see if it works. and it does. and
>>> you can google this group for my experience with a friend's slack spoked
>>> mtb wheel. you should try it too. your only problem is spoke nipples
>>> unscrewing.
>>
>> So, once again the photograph you offered as proof turns out to be no sort
>> of proof at all.
>
> so you're saying that pic is a fabrication? it's holding my full body
> weight. i am the heaviest thing in my house. what more do you want
> gary?
As I've said elsewhere, what I would expect before taking your claims
seriously is an experiment that actually tests Jobst's claims. That would
require subjecting your wheel to a significant side load. You haven't done
that.
> of course, you /could/ bother to replicate my experiment rather
> than simply bellyache, but that's not an armchair exercise.
Replicate? You haven't done an experiment that tests Jobst's claims.
What's to replicate? And no, I won't be the one to do the initial
experiment for you. I don't risk expensive equipment on the word of an
anonymous internet crank.
|
| | |
Date: 20 Jul 2007 18:53:12
From: jim beam
Subject: Re: spoke tension
|
Gary Young wrote:
> On Thu, 19 Jul 2007 05:54:37 -0700, jim beam wrote:
>
>> Gary Young wrote:
>>> On Wed, 18 Jul 2007 21:43:17 -0700, jim beam wrote:
>>>
>>>> Johnny Sunset aka Tom Sherman wrote:
>>>>> "jim beam" ? wrote:
>>>>>> Johnny Sunset aka Tom Sherman wrote:
>>>>>>> "jim beam" ? wrote:
>>>>>>>> ...
>>>>>>>> in your book, you also argue that rims collapse as soon as spokes go
>>>>>>>> slack go slack....
>>>>>>>> http://www.flickr.com/photos/38636024@N00/417157612/
>>>>>>> How far did you ride on that wheel?
>>>>>>>
>>>>>> as far as i could without the tensiometer falling off... wise guy.
>>>>>>
>>>>>> how about you address the point of the posting: "...the wheel can
>>>>>> support loads only to the point where its spokes become loose. at
>>>>>> this point the wheel will collapse." jobst brandt. "the book". 3rd
>>>>>> edition.
>>>>> Would "jim beam's" wheel with missing spokes collapse if ridden? If so,
>>>>> JB is right (for all practical purposes) and jb is wrong.
>>>>>
>>>> i've ridden a slack spoked wheel so see if it works. and it does. and
>>>> you can google this group for my experience with a friend's slack spoked
>>>> mtb wheel. you should try it too. your only problem is spoke nipples
>>>> unscrewing.
>>> So, once again the photograph you offered as proof turns out to be no sort
>>> of proof at all.
>> so you're saying that pic is a fabrication? it's holding my full body
>> weight. i am the heaviest thing in my house. what more do you want
>> gary?
>
> As I've said elsewhere, what I would expect before taking your claims
> seriously is an experiment that actually tests Jobst's claims. That would
> require subjecting your wheel to a significant side load. You haven't done
> that.
>
>> of course, you /could/ bother to replicate my experiment rather
>> than simply bellyache, but that's not an armchair exercise.
>
> Replicate? You haven't done an experiment that tests Jobst's claims.
> What's to replicate? And no, I won't be the one to do the initial
> experiment for you. I don't risk expensive equipment on the word of an
> anonymous internet crank.
hmmm. i put my money where my mouth is and i post the results. what do
you do? [other than just bleat from the sidelines of course.]
and that's a rhetorical question.
|
| |
Date: 19 Jul 2007 08:14:36
From: Gary Young
Subject: Re: spoke tension
|
On Thu, 19 Jul 2007 05:51:38 -0700, jim beam wrote:
> Gary Young wrote:
>> On Wed, 18 Jul 2007 21:48:33 -0700, jim beam wrote:
>>
>>> Peter Cole wrote:
>>>> jim beam wrote:
>>>>> jobst.brandt@stanfordalumni.org wrote:
>>>>>> http://www.jimbeam.com/beam/default.aspx? writes:
>>>>>>
>>>>>>>>>> Could someone recommend the proper spoke tension for a rear wheel
>>>>>>>>>> built with a Velocity Aerohead OC rim?
>>>>>>>>> JB says tension as high as the rim will bear without taking a
>>>>>>>>> "taco" or "potato chip" shape; however, jb says tension only as
>>>>>>>>> high as the manufacturer's recommendation, or the rim will crack
>>>>>>>>> around the spoke hole.
>>>>>>>>> LET THE BATTLE BEGIN!
>>>>>>>> That's not really what Jobst says. It's what jim beam says Jobst
>>>>>>>> says, which are usually two (often very) different things. I guess
>>>>>>>> you didn't read the book, either.
>>>>>>> "as high as the rim can bear" is what jobst says on this group.
>>>>>>> "spokes must be as tight as the rim permits" is what he says in "the
>>>>>>> book". [3rd edition.]
>>>>>>> either way, he equates increasing spoke tension with increasing
>>>>>>> wheel strength: "a wheel with spoke tension near the limit of rim
>>>>>>> strength can support large loads easily" - which is untrue,
>>>>>>> misleading and reveals gross misunderstanding.
>>>>>> I think such statements need a bit of evidence to be credible.
>>>>>>
>>>>>> A wire spoked bicycle wheel can carry loads up to the point where its
>>>>>> spokes become slack from compression as they pass the load point on
>>>>>> the road. The looser the spokes the more easily this occurs and
>>>>>> conversely the tighter the spoke the less this occurs.
>>>>> as discussed on several prior occasions, you are only considering the
>>>>> spokes, not the rim. increasing spoke tension increases
>>>>> circumferential rim compression. but you miss the point that as the
>>>>> rim's compression rises, its load capacity decreases.
>>>>>
>>>>> let's assume an aluminum beam has the same tensile strength as it does
>>>>> compression. let's say that it yields at [pick a number] +/- 100Mpa.
>>>>> in plain bending, the compressive side yields at the same time as the
>>>>> tensile side - when this limit is reached. now, compress the beam
>>>>> longitudinally at say 50Mpa, i.e. superimpose a stress on it. the
>>>>> tensile side of the beam can now support 100 + 50 = 150Mpa before
>>>>> yield. but the compressive side can only support 100 - 50 = 50Mpa.
>>>>> so if i bend it now, the beam will start to yield supporting only half
>>>>> the load it did before.
>>>>>
>>>>> with materials with no tensile strength like concrete, you "borrow"
>>>>> from the material's [ample] compressive strength to give it pseudo
>>>>> tensile strength. but with a material as strong in compression as
>>>>> tension, like an aluminum bike rim, that's simply counter-productive.
>>>> You simply can't explain something as complex as a spoked wheel with
>>>> this homespun approach. It's difficult to put in layman's terms, but the
>>>> math is all worked out. Perhaps you could break down and actually read
>>>> Jobst's book or Gavin's paper (which are completely consistent).
>>>>
>>>> Jobst won't rebut your rantings because (I assume) you're such an
>>>> abusive SOB. I can't blame him for that, but somebody has to call your
>>>> BS. Of course many have in the past, but you just take a breather &
>>>> start up again as if nothing happened.
>>>>
>>>> Analysis of a spoked wheel is a complex engineering exercise, the
>>>> principles are not intuitively obvious, otherwise Gavin wouldn't have
>>>> filled several pages with math and Jobst with FEA results. Hand waving
>>>> doesn't cut it, even with the gratuitous introduction of a couple of
>>>> numbers.
>>>>
>>>> Inaccurately paraphrasing a book you've never read doesn't help, either.
>>> finite element analysis is examining small elements. any small element
>>> when loaded above yield will, well, yield! i don't care how you try to
>>> obscure the facts with ad hominem. the fact is, any single element when
>>> loaded above yield will permanently deform. and in a bike wheel, that
>>> is failure. i've broken the facts down into the simplest possible
>>> elements. dispute them.
>>
>> I've disputed them in a post to which you haven't responded. At the
>> beginning stage of wheel failure there is no yielding of the rim.
>
> that is the most profoundly ridiculous statement i've seen outside of
> "the book".
>
>
As I've said in another post to which you didn't respond, a wheel
tensioned to the point where it begins to potato chip will resume its
original shape when the tension is reduced. To my mind, that means that
the rim was elastically deformed. What is your explanation?
>>
>>> don't retreat into b.s. analyze.
|
| | |
Date: 20 Jul 2007 18:55:57
From: jim beam
Subject: Re: spoke tension
|
Gary Young wrote:
> On Thu, 19 Jul 2007 05:51:38 -0700, jim beam wrote:
>
>> Gary Young wrote:
>>> On Wed, 18 Jul 2007 21:48:33 -0700, jim beam wrote:
>>>
>>>> Peter Cole wrote:
>>>>> jim beam wrote:
>>>>>> jobst.brandt@stanfordalumni.org wrote:
>>>>>>> http://www.jimbeam.com/beam/default.aspx? writes:
>>>>>>>
>>>>>>>>>>> Could someone recommend the proper spoke tension for a rear wheel
>>>>>>>>>>> built with a Velocity Aerohead OC rim?
>>>>>>>>>> JB says tension as high as the rim will bear without taking a
>>>>>>>>>> "taco" or "potato chip" shape; however, jb says tension only as
>>>>>>>>>> high as the manufacturer's recommendation, or the rim will crack
>>>>>>>>>> around the spoke hole.
>>>>>>>>>> LET THE BATTLE BEGIN!
>>>>>>>>> That's not really what Jobst says. It's what jim beam says Jobst
>>>>>>>>> says, which are usually two (often very) different things. I guess
>>>>>>>>> you didn't read the book, either.
>>>>>>>> "as high as the rim can bear" is what jobst says on this group.
>>>>>>>> "spokes must be as tight as the rim permits" is what he says in "the
>>>>>>>> book". [3rd edition.]
>>>>>>>> either way, he equates increasing spoke tension with increasing
>>>>>>>> wheel strength: "a wheel with spoke tension near the limit of rim
>>>>>>>> strength can support large loads easily" - which is untrue,
>>>>>>>> misleading and reveals gross misunderstanding.
>>>>>>> I think such statements need a bit of evidence to be credible.
>>>>>>>
>>>>>>> A wire spoked bicycle wheel can carry loads up to the point where its
>>>>>>> spokes become slack from compression as they pass the load point on
>>>>>>> the road. The looser the spokes the more easily this occurs and
>>>>>>> conversely the tighter the spoke the less this occurs.
>>>>>> as discussed on several prior occasions, you are only considering the
>>>>>> spokes, not the rim. increasing spoke tension increases
>>>>>> circumferential rim compression. but you miss the point that as the
>>>>>> rim's compression rises, its load capacity decreases.
>>>>>>
>>>>>> let's assume an aluminum beam has the same tensile strength as it does
>>>>>> compression. let's say that it yields at [pick a number] +/- 100Mpa.
>>>>>> in plain bending, the compressive side yields at the same time as the
>>>>>> tensile side - when this limit is reached. now, compress the beam
>>>>>> longitudinally at say 50Mpa, i.e. superimpose a stress on it. the
>>>>>> tensile side of the beam can now support 100 + 50 = 150Mpa before
>>>>>> yield. but the compressive side can only support 100 - 50 = 50Mpa.
>>>>>> so if i bend it now, the beam will start to yield supporting only half
>>>>>> the load it did before.
>>>>>>
>>>>>> with materials with no tensile strength like concrete, you "borrow"
>>>>>> from the material's [ample] compressive strength to give it pseudo
>>>>>> tensile strength. but with a material as strong in compression as
>>>>>> tension, like an aluminum bike rim, that's simply counter-productive.
>>>>> You simply can't explain something as complex as a spoked wheel with
>>>>> this homespun approach. It's difficult to put in layman's terms, but the
>>>>> math is all worked out. Perhaps you could break down and actually read
>>>>> Jobst's book or Gavin's paper (which are completely consistent).
>>>>>
>>>>> Jobst won't rebut your rantings because (I assume) you're such an
>>>>> abusive SOB. I can't blame him for that, but somebody has to call your
>>>>> BS. Of course many have in the past, but you just take a breather &
>>>>> start up again as if nothing happened.
>>>>>
>>>>> Analysis of a spoked wheel is a complex engineering exercise, the
>>>>> principles are not intuitively obvious, otherwise Gavin wouldn't have
>>>>> filled several pages with math and Jobst with FEA results. Hand waving
>>>>> doesn't cut it, even with the gratuitous introduction of a couple of
>>>>> numbers.
>>>>>
>>>>> Inaccurately paraphrasing a book you've never read doesn't help, either.
>>>> finite element analysis is examining small elements. any small element
>>>> when loaded above yield will, well, yield! i don't care how you try to
>>>> obscure the facts with ad hominem. the fact is, any single element when
>>>> loaded above yield will permanently deform. and in a bike wheel, that
>>>> is failure. i've broken the facts down into the simplest possible
>>>> elements. dispute them.
>>> I've disputed them in a post to which you haven't responded. At the
>>> beginning stage of wheel failure there is no yielding of the rim.
>> that is the most profoundly ridiculous statement i've seen outside of
>> "the book".
>>
>>
>
> As I've said in another post to which you didn't respond, a wheel
> tensioned to the point where it begins to potato chip will resume its
> original shape when the tension is reduced. To my mind, that means that
> the rim was elastically deformed. What is your explanation?
eh?
>
>
>>>> don't retreat into b.s. analyze.
|
| |
Date: 19 Jul 2007 07:29:05
From: Gary Young
Subject: Re: spoke tension
|
On Wed, 18 Jul 2007 21:43:17 -0700, jim beam wrote:
> Johnny Sunset aka Tom Sherman wrote:
>> "jim beam" ? wrote:
>>> Johnny Sunset aka Tom Sherman wrote:
>>>> "jim beam" ? wrote:
>>>>> ...
>>>>> in your book, you also argue that rims collapse as soon as spokes go
>>>>> slack go slack....
>>>>> http://www.flickr.com/photos/38636024@N00/417157612/
>>>>
>>>> How far did you ride on that wheel?
>>>>
>>> as far as i could without the tensiometer falling off... wise guy.
>>>
>>> how about you address the point of the posting: "...the wheel can
>>> support loads only to the point where its spokes become loose. at
>>> this point the wheel will collapse." jobst brandt. "the book". 3rd
>>> edition.
>>
>> Would "jim beam's" wheel with missing spokes collapse if ridden? If so,
>> JB is right (for all practical purposes) and jb is wrong.
>>
> i've ridden a slack spoked wheel so see if it works. and it does. and
> you can google this group for my experience with a friend's slack spoked
> mtb wheel. you should try it too. your only problem is spoke nipples
> unscrewing.
So, once again the photograph you offered as proof turns out to be no sort
of proof at all.
|
| | |
Date: 19 Jul 2007 05:54:37
From: jim beam
Subject: Re: spoke tension
|
Gary Young wrote:
> On Wed, 18 Jul 2007 21:43:17 -0700, jim beam wrote:
>
>> Johnny Sunset aka Tom Sherman wrote:
>>> "jim beam" ? wrote:
>>>> Johnny Sunset aka Tom Sherman wrote:
>>>>> "jim beam" ? wrote:
>>>>>> ...
>>>>>> in your book, you also argue that rims collapse as soon as spokes go
>>>>>> slack go slack....
>>>>>> http://www.flickr.com/photos/38636024@N00/417157612/
>>>>> How far did you ride on that wheel?
>>>>>
>>>> as far as i could without the tensiometer falling off... wise guy.
>>>>
>>>> how about you address the point of the posting: "...the wheel can
>>>> support loads only to the point where its spokes become loose. at
>>>> this point the wheel will collapse." jobst brandt. "the book". 3rd
>>>> edition.
>>> Would "jim beam's" wheel with missing spokes collapse if ridden? If so,
>>> JB is right (for all practical purposes) and jb is wrong.
>>>
>> i've ridden a slack spoked wheel so see if it works. and it does. and
>> you can google this group for my experience with a friend's slack spoked
>> mtb wheel. you should try it too. your only problem is spoke nipples
>> unscrewing.
>
> So, once again the photograph you offered as proof turns out to be no sort
> of proof at all.
so you're saying that pic is a fabrication? it's holding my full body
weight. i am the heaviest thing in my house. what more do you want
gary? of course, you /could/ bother to replicate my experiment rather
than simply bellyache, but that's not an armchair exercise.
|
| |
Date: 19 Jul 2007 07:28:05
From: Gary Young
Subject: Re: spoke tension
|
On Wed, 18 Jul 2007 21:48:33 -0700, jim beam wrote:
> Peter Cole wrote:
>> jim beam wrote:
>>> jobst.brandt@stanfordalumni.org wrote:
>>>> http://www.jimbeam.com/beam/default.aspx? writes:
>>>>
>>>>>>>> Could someone recommend the proper spoke tension for a rear wheel
>>>>>>>> built with a Velocity Aerohead OC rim?
>>>>
>>>>>>> JB says tension as high as the rim will bear without taking a
>>>>>>> "taco" or "potato chip" shape; however, jb says tension only as
>>>>>>> high as the manufacturer's recommendation, or the rim will crack
>>>>>>> around the spoke hole.
>>>>
>>>>>>> LET THE BATTLE BEGIN!
>>>>
>>>>>> That's not really what Jobst says. It's what jim beam says Jobst
>>>>>> says, which are usually two (often very) different things. I guess
>>>>>> you didn't read the book, either.
>>>>
>>>>> "as high as the rim can bear" is what jobst says on this group.
>>>>
>>>>> "spokes must be as tight as the rim permits" is what he says in "the
>>>>> book". [3rd edition.]
>>>>
>>>>> either way, he equates increasing spoke tension with increasing
>>>>> wheel strength: "a wheel with spoke tension near the limit of rim
>>>>> strength can support large loads easily" - which is untrue,
>>>>> misleading and reveals gross misunderstanding.
>>>>
>>>> I think such statements need a bit of evidence to be credible.
>>>>
>>>> A wire spoked bicycle wheel can carry loads up to the point where its
>>>> spokes become slack from compression as they pass the load point on
>>>> the road. The looser the spokes the more easily this occurs and
>>>> conversely the tighter the spoke the less this occurs.
>>>
>>> as discussed on several prior occasions, you are only considering the
>>> spokes, not the rim. increasing spoke tension increases
>>> circumferential rim compression. but you miss the point that as the
>>> rim's compression rises, its load capacity decreases.
>>>
>>> let's assume an aluminum beam has the same tensile strength as it does
>>> compression. let's say that it yields at [pick a number] +/- 100Mpa.
>>> in plain bending, the compressive side yields at the same time as the
>>> tensile side - when this limit is reached. now, compress the beam
>>> longitudinally at say 50Mpa, i.e. superimpose a stress on it. the
>>> tensile side of the beam can now support 100 + 50 = 150Mpa before
>>> yield. but the compressive side can only support 100 - 50 = 50Mpa.
>>> so if i bend it now, the beam will start to yield supporting only half
>>> the load it did before.
>>>
>>> with materials with no tensile strength like concrete, you "borrow"
>>> from the material's [ample] compressive strength to give it pseudo
>>> tensile strength. but with a material as strong in compression as
>>> tension, like an aluminum bike rim, that's simply counter-productive.
>>
>> You simply can't explain something as complex as a spoked wheel with
>> this homespun approach. It's difficult to put in layman's terms, but the
>> math is all worked out. Perhaps you could break down and actually read
>> Jobst's book or Gavin's paper (which are completely consistent).
>>
>> Jobst won't rebut your rantings because (I assume) you're such an
>> abusive SOB. I can't blame him for that, but somebody has to call your
>> BS. Of course many have in the past, but you just take a breather &
>> start up again as if nothing happened.
>>
>> Analysis of a spoked wheel is a complex engineering exercise, the
>> principles are not intuitively obvious, otherwise Gavin wouldn't have
>> filled several pages with math and Jobst with FEA results. Hand waving
>> doesn't cut it, even with the gratuitous introduction of a couple of
>> numbers.
>>
>> Inaccurately paraphrasing a book you've never read doesn't help, either.
>
> finite element analysis is examining small elements. any small element
> when loaded above yield will, well, yield! i don't care how you try to
> obscure the facts with ad hominem. the fact is, any single element when
> loaded above yield will permanently deform. and in a bike wheel, that
> is failure. i've broken the facts down into the simplest possible
> elements. dispute them.
I've disputed them in a post to which you haven't responded. At the
beginning stage of wheel failure there is no yielding of the rim.
> don't retreat into b.s. analyze.
|
| | |
Date: 19 Jul 2007 05:51:38
From: jim beam
Subject: Re: spoke tension
|
Gary Young wrote:
> On Wed, 18 Jul 2007 21:48:33 -0700, jim beam wrote:
>
>> Peter Cole wrote:
>>> jim beam wrote:
>>>> jobst.brandt@stanfordalumni.org wrote:
>>>>> http://www.jimbeam.com/beam/default.aspx? writes:
>>>>>
>>>>>>>>> Could someone recommend the proper spoke tension for a rear wheel
>>>>>>>>> built with a Velocity Aerohead OC rim?
>>>>>>>> JB says tension as high as the rim will bear without taking a
>>>>>>>> "taco" or "potato chip" shape; however, jb says tension only as
>>>>>>>> high as the manufacturer's recommendation, or the rim will crack
>>>>>>>> around the spoke hole.
>>>>>>>> LET THE BATTLE BEGIN!
>>>>>>> That's not really what Jobst says. It's what jim beam says Jobst
>>>>>>> says, which are usually two (often very) different things. I guess
>>>>>>> you didn't read the book, either.
>>>>>> "as high as the rim can bear" is what jobst says on this group.
>>>>>> "spokes must be as tight as the rim permits" is what he says in "the
>>>>>> book". [3rd edition.]
>>>>>> either way, he equates increasing spoke tension with increasing
>>>>>> wheel strength: "a wheel with spoke tension near the limit of rim
>>>>>> strength can support large loads easily" - which is untrue,
>>>>>> misleading and reveals gross misunderstanding.
>>>>> I think such statements need a bit of evidence to be credible.
>>>>>
>>>>> A wire spoked bicycle wheel can carry loads up to the point where its
>>>>> spokes become slack from compression as they pass the load point on
>>>>> the road. The looser the spokes the more easily this occurs and
>>>>> conversely the tighter the spoke the less this occurs.
>>>> as discussed on several prior occasions, you are only considering the
>>>> spokes, not the rim. increasing spoke tension increases
>>>> circumferential rim compression. but you miss the point that as the
>>>> rim's compression rises, its load capacity decreases.
>>>>
>>>> let's assume an aluminum beam has the same tensile strength as it does
>>>> compression. let's say that it yields at [pick a number] +/- 100Mpa.
>>>> in plain bending, the compressive side yields at the same time as the
>>>> tensile side - when this limit is reached. now, compress the beam
>>>> longitudinally at say 50Mpa, i.e. superimpose a stress on it. the
>>>> tensile side of the beam can now support 100 + 50 = 150Mpa before
>>>> yield. but the compressive side can only support 100 - 50 = 50Mpa.
>>>> so if i bend it now, the beam will start to yield supporting only half
>>>> the load it did before.
>>>>
>>>> with materials with no tensile strength like concrete, you "borrow"
>>>> from the material's [ample] compressive strength to give it pseudo
>>>> tensile strength. but with a material as strong in compression as
>>>> tension, like an aluminum bike rim, that's simply counter-productive.
>>> You simply can't explain something as complex as a spoked wheel with
>>> this homespun approach. It's difficult to put in layman's terms, but the
>>> math is all worked out. Perhaps you could break down and actually read
>>> Jobst's book or Gavin's paper (which are completely consistent).
>>>
>>> Jobst won't rebut your rantings because (I assume) you're such an
>>> abusive SOB. I can't blame him for that, but somebody has to call your
>>> BS. Of course many have in the past, but you just take a breather &
>>> start up again as if nothing happened.
>>>
>>> Analysis of a spoked wheel is a complex engineering exercise, the
>>> principles are not intuitively obvious, otherwise Gavin wouldn't have
>>> filled several pages with math and Jobst with FEA results. Hand waving
>>> doesn't cut it, even with the gratuitous introduction of a couple of
>>> numbers.
>>>
>>> Inaccurately paraphrasing a book you've never read doesn't help, either.
>> finite element analysis is examining small elements. any small element
>> when loaded above yield will, well, yield! i don't care how you try to
>> obscure the facts with ad hominem. the fact is, any single element when
>> loaded above yield will permanently deform. and in a bike wheel, that
>> is failure. i've broken the facts down into the simplest possible
>> elements. dispute them.
>
> I've disputed them in a post to which you haven't responded. At the
> beginning stage of wheel failure there is no yielding of the rim.
that is the most profoundly ridiculous statement i've seen outside of
"the book".
>
>> don't retreat into b.s. analyze.
|
| |
Date: 18 Jul 2007 20:57:01
From:
Subject: Re: spoke tension
|
On Jul 16, 10:19 pm, mark <markfel...@earthlink.net > wrote:
> Could someone recommend the proper spoke tension for a rear wheel built
> with a Velocity Aerohead OC rim?
>
> TIA,
>
> mark
>From Velocity USA:
"We aim for around 105-115 kgf for front wheels, 110-120 kgf for rear
wheels. This applies to all of our rims."
|
| |
Date: 18 Jul 2007 13:10:02
From: Jay Beattie
Subject: Re: spoke tension
|
On Jul 17, 7:00 am, Tim McNamara <tim...@bitstream.net > wrote:
> In article <1184674576.251361.327...@m37g2000prh.googlegroups.com>,
> Qui si parla Campagnolo <pe...@vecchios.com> wrote:
>
> > On Jul 16, 11:19 pm, mark <markfel...@earthlink.net> wrote:
> > > Could someone recommend the proper spoke tension for a rear wheel
> > > built with a Velocity Aerohead OC rim?
>
> > 100 kgf for the right side.
>
> Which is pretty much the standard number used for the drive side of the
> rear wheel and both sides of the front wheel for just about any wheel
> with a normal number of spokes (32-36). Except for Mavic who recommend
> 95 kgf, according to previously published information.
I don't use linseed oil and find that 100 kgf is too low to keep the
spokes from going slack because I am a big 200lb+ kind of guy. Going
above 120 kgf, however, resulted in cracked spoke holes. So I build
just below that. Great rims. I wish there were more OC rims on the
market. -- Jay Beattie.
|
| |
Date: 18 Jul 2007 09:17:30
From: Gary Young
Subject: Re: spoke tension
|
On Tue, 17 Jul 2007 22:33:59 -0700, jim beam wrote:
> jobst.brandt@stanfordalumni.org wrote:
>> http://www.jimbeam.com/beam/default.aspx? writes:
>>
>>>>>> Could someone recommend the proper spoke tension for a rear wheel
>>>>>> built with a Velocity Aerohead OC rim?
>>
>>>>> JB says tension as high as the rim will bear without taking a
>>>>> "taco" or "potato chip" shape; however, jb says tension only as
>>>>> high as the manufacturer's recommendation, or the rim will crack
>>>>> around the spoke hole.
>>
>>>>> LET THE BATTLE BEGIN!
>>
>>>> That's not really what Jobst says. It's what jim beam says Jobst
>>>> says, which are usually two (often very) different things. I guess
>>>> you didn't read the book, either.
>>
>>> "as high as the rim can bear" is what jobst says on this group.
>>
>>> "spokes must be as tight as the rim permits" is what he says in "the
>>> book". [3rd edition.]
>>
>>> either way, he equates increasing spoke tension with increasing
>>> wheel strength: "a wheel with spoke tension near the limit of rim
>>> strength can support large loads easily" - which is untrue,
>>> misleading and reveals gross misunderstanding.
>>
>> I think such statements need a bit of evidence to be credible.
>>
>> A wire spoked bicycle wheel can carry loads up to the point where its
>> spokes become slack from compression as they pass the load point on
>> the road. The looser the spokes the more easily this occurs and
>> conversely the tighter the spoke the less this occurs.
>
> as discussed on several prior occasions, you are only considering the
> spokes, not the rim. increasing spoke tension increases circumferential
> rim compression. but you miss the point that as the rim's compression
> rises, its load capacity decreases.
>
> let's assume an aluminum beam has the same tensile strength as it does
> compression. let's say that it yields at [pick a number] +/- 100Mpa.
> in plain bending, the compressive side yields at the same time as the
> tensile side - when this limit is reached. now, compress the beam
> longitudinally at say 50Mpa, i.e. superimpose a stress on it. the
> tensile side of the beam can now support 100 + 50 = 150Mpa before yield.
> but the compressive side can only support 100 - 50 = 50Mpa. so if i
> bend it now, the beam will start to yield supporting only half the load
> it did before.
>
I've always been curious about your emphasis on yield when discussing
wheel failure. It seems to me to be of a piece with your error in equating
the lateral stiffness of a wheel with its ultimate resistance to failure
when subjected to lateral loads.
When I use Jobst's method to reach the proper spoke tension, there comes a
time when the rim begins to take on the potato chip shape. However, when I
back off the nipples half a turn, the rim returns to trueness. That
indicates that there's been no yielding, doesn't it? Of course, once a
wheel has completely potato-chipped, an aluminum rim will be
permanently bent. However, it seems to me that the yielding is more likely
a by-product of wheel failure than a cause of it or a necessary
concomitant.
> with materials with no tensile strength like concrete, you "borrow" from
> the material's [ample] compressive strength to give it pseudo tensile
> strength. but with a material as strong in compression as tension, like
> an aluminum bike rim, that's simply counter-productive.
>
> in your book, you also argue that rims collapse as soon as spokes go
> slack go slack....
> http://www.flickr.com/photos/38636024@N00/417157612/
>
> writing a book is one thing. understanding what to put in it is quite
> another.
>
>
>>
>> I have ridden many 100k miles with wheels tensioned as described
>> without needing to re-true them or to replace cracked rims. These
>> have been socketed tubular rims (Fiamme, Super Champion, and Mavic)
>> and Super Champion "Gentleman" and Mavic MA-2 clincher rims. I still
>> ride the latter as do most of my fellow riders, ones who do not see
>> themselves as professional like racers..
>>
>> When riding rough roads such as described in rec.bicycles.rides "Last
>> chance road", I and my bikie friends wonder if the light weight "with
>> it" crowd ever experience roads that are demanding on 36-spoke wheels.
>>
>> http://tinyurl.com/2uc6tb
>>
>> Dings in rims also come from insufficient inflation, a parallel to
>> insufficient spoke tension in supporting loads.
>>
>> http://geocities.com/rayhosler/slideshow.html
>>
>> Ride bike!
>
> red herring.
|
| |
Date: 18 Jul 2007 08:54:38
From: Gary Young
Subject: Re: spoke tension
|
On Wed, 18 Jul 2007 06:02:26 -0700, jim beam wrote:
> Johnny Sunset aka Tom Sherman wrote:
>> "jim beam" ? wrote:
>>> ...
>>> in your book, you also argue that rims collapse as soon as spokes go
>>> slack go slack....
>>> http://www.flickr.com/photos/38636024@N00/417157612/
>>
>> How far did you ride on that wheel?
>>
> as far as i could without the tensiometer falling off... wise guy.
>
If you were worried about the tensiometer being damaged, you could always
remove it before you begin riding. Or don't you know how to recognize
wheel failure without a tensiometer?
> how about you address the point of the posting: "...the wheel can
> support loads only to the point where its spokes become loose. at this
> point the wheel will collapse." jobst brandt. "the book". 3rd edition.
It would be helpful if you would provide a page reference. I suspect
you're leaving out context. Jobst takes pains in several places to say
that an untensioned wheel is vulnerable to lateral or side loads. See, for
instance, page 28: "[T]he sudden collapse of a wheel is caused -- with few
exceptions -- by excessive side loads." Did your experiment subject the
wheel to a side load? It seems to me that it did not.
|
| |
Date: 18 Jul 2007 08:37:28
From: Gary Young
Subject: Re: spoke tension
|
On Wed, 18 Jul 2007 00:16:08 -0500, Johnny Sunset aka Tom Sherman wrote:
> jobst.brandt@stanfordalumni.org aka Jobst Brandt wrote:
>> ...
>> Dings in rims also come from insufficient inflation...
>
> During the Weimar Republic era, German riders found their rims
> impervious to damage from potholes and other impacts.
>
Or so they reported. But of course we can never really know der ding an
sich.
|
| |
Date: 18 Jul 2007 12:01:21
From: Qui si parla Campagnolo
Subject: Re: spoke tension
|
On Jul 17, 6:26 am, mark <markfel...@earthlink.net > wrote:
> Thank you.
>
> mark
>
> Qui si parla Campagnolo wrote:
>
> > On Jul 16, 11:19 pm, mark <markfel...@earthlink.net> wrote:
> >> Could someone recommend the proper spoke tension for a rear wheel built
> >> with a Velocity Aerohead OC rim?
>
> >> TIA,
>
> >> mark
>
> > 100 kgf for the right side. If true, round, dished..the left side
> > tension will take care of itself.
Happy to help-email direct or on this NG if you have anyother ?.
|
| |
Date: 17 Jul 2007 01:19:22
From: Johnny Sunset aka Tom Sherman
Subject: Re: spoke tension
|
Mark Felber wrote:
> Could someone recommend the proper spoke tension for a rear wheel built
> with a Velocity Aerohead OC rim?
JB says tension as high as the rim will bear without taking a "taco" or
"potato chip" shape; however, jb says tension only as high as the
manufacturer's recommendation, or the rim will crack around the spoke hole.
LET THE BATTLE BEGIN!
--
Tom Sherman - Holstein-Friesland Bovinia
The weather is here, wish you were beautiful
--
Posted via a free Usenet account from http://www.teranews.com
|
| | |
Date: 21 Jul 2007 15:42:39
From: Gary Young
Subject: Re: spoke tension
|
On Sat, 21 Jul 2007 12:44:51 -0600, carlfogel wrote:
> On Sat, 21 Jul 2007 12:52:51 -0500, Gary Young <garyyoung3@gmail.com>
> wrote:
>
>>On Sat, 21 Jul 2007 10:39:04 -0700, Ron Ruff wrote:
>>
>>> On Jul 18, 7:02 am, jim beam <spamvor...@bad.example.net> wrote:
>>>> how about you address the point of the posting: "...the wheel can
>>>> support loads only to the point where its spokes become loose. at this
>>>> point the wheel will collapse." jobst brandt. "the book". 3rd edition.
>>>
>>> Maybe an exaggeration... but close to the truth. When spokes become
>>> slack they no longer provide support to the rim, so the rim is sort of
>>> on it's own. It's stiffness and strength and resistance to buckling
>>> drops a lot.
>>
>>I wouldn't go so far as to call it an exaggeration until "jim beam"
>>supplies a page reference (he's ignored my request for that). Jobst is
>>usually careful to say that a slack wheel is vulnerable primarily to side
>>loads. "Jim beam" may well have quoted selectively to obscure the context.
>>Furthermore, even if Jobst exaggerated at one point, it's simply sophistry
>>to ignore the qualifying remarks he makes at other points in the book.
>
> Dear Gary,
>
> You're interested in textual references? How nice! There's nothing
> like a good discussion of the vexing problem of how to cut and paste
> together a version of Hamlet that combines the various quartos
> (published without Shakespeare's consent during his lifetime) with the
> version found in the First Folio of 1623, published also without his
> consent, seven years after his death. Unlike Macbeth, for which we
> have only the First Folio version and thus no scholarly debate--
>
> Oh, you're only interested in "The Bicycle Wheel"?
>
> Well, there are three English editions of Jobst's book, plus one in
> German that we will ignore.
>
> The two later editions add a little material and subtract a little
> material, but they mainly reword things, often sentence by sentence.
>
> This inch-by-inch rephrasing makes it horribly difficult to find a
> particular passage.
>
> Even worse from a scholarly point of view, the theoretical material in
> the first part is often repeated in the second practical part, so you
> may be looking at the wrong end of the book.
>
> Frequently the reader hits an it's-explained-elsewhere comment, but
> there's no page number given and no index.
>
> (A scanned and searchable version obtained from unethical sources
> helps immensely. Anyone willing to profit from piracy is welcome to
> ask me to search for a phrase from the 3rd edition, since it only
> takes a few moments.)
>
> To be fair, Jobst was no more writing for scholars than Shakespeare
> was, and Jim faces a hideous scholarly task if he wants to footnote
> properly.
>
> ***
>
> Here's the first edition (1981, 1983), illustrated by Sherry
> Sheffield-Boulton, p. 78:
>
> SPOKE TENSION
>
> The correct tension for a wheel must be a balance between rim strength
> and wheel stability. The spokes should be as tight as the rim permits
> for maxium strength. However, for practical reasonss the spokes should
> be slightly looser than this because at the maximum tension, the
> failure of one spoke may destroy the rim.
>
> ***
>
> Here's the second edition (1981, 1983, 1988, 7th printing 1990),
> illustrated by Sherry Sheffield Boulton (no dash), p. 76:
>
> SPOKE TENSION
>
> The correct tension for a wheel is a balance between rim strength and
> wheel stability. For greatest strength, spokes should be as tight as
> the rim permits. In practice, however, spokes should be slightly
> looser because when they are at the limit, failure of a single spoke
> can severely deform the rim.
>
> ***
>
> And here's the third edition (1993), illustrated by Sherry Sheffield
> (no Boulton), page 71:
>
> SPOKE TENSION
>
> With tensioned wires as spokes, the wheel can support loads only to
> the point where its spokes become loose. At this point the wheel will
> collapse. Therefore, for greatest strength, spokes must be as tight as
> the rim permits. . . .
>
> [skip the rest of the paragraph and jump ~80 words to where the next
> sentence has been moved]
>
> In practice, however, spokes should be slightly looser than the
> maximum the rim can sustain, because at maximum tension, failure of a
> single spoke can severely deform the rim.
>
> ***
>
> I defy anyone to find a more trivial example of the trivial changes
> between the three editions than the illustrator's name (which may have
> been far from trivial to her).
>
> Anyway, there's the text and the page numbers and some explanation why
> quoting from various editions of "The Bicycle Wheel" is something that
> only the truly pedantic can enjoy.
>
> Cheers,
>
> Carl Fogel
Carl,
Thanks for supplying the quotation, but I do think you exaggerate the
difficulties "jim beam" faced. He said in an earlier post that he took the
quotation from the third edition and should have been able to supply a
page.
In any event, judging from the discussion taking place between Jobst and
Peter Cole right now, I'm getting the impression that I've once again
allowed my zeal to expose jim beam's nonsense take me beyond my knowledge.
I'm going to try to be humble for awhile.
|
| | | |
Date: 21 Jul 2007 15:20:07
From:
Subject: Re: spoke tension
|
On Sat, 21 Jul 2007 15:42:39 -0500, Gary Young <garyyoung3@gmail.com >
wrote:
>On Sat, 21 Jul 2007 12:44:51 -0600, carlfogel wrote:
>
>> On Sat, 21 Jul 2007 12:52:51 -0500, Gary Young <garyyoung3@gmail.com>
>> wrote:
>>
>>>On Sat, 21 Jul 2007 10:39:04 -0700, Ron Ruff wrote:
>>>
>>>> On Jul 18, 7:02 am, jim beam <spamvor...@bad.example.net> wrote:
>>>>> how about you address the point of the posting: "...the wheel can
>>>>> support loads only to the point where its spokes become loose. at this
>>>>> point the wheel will collapse." jobst brandt. "the book". 3rd edition.
>>>>
>>>> Maybe an exaggeration... but close to the truth. When spokes become
>>>> slack they no longer provide support to the rim, so the rim is sort of
>>>> on it's own. It's stiffness and strength and resistance to buckling
>>>> drops a lot.
>>>
>>>I wouldn't go so far as to call it an exaggeration until "jim beam"
>>>supplies a page reference (he's ignored my request for that). Jobst is
>>>usually careful to say that a slack wheel is vulnerable primarily to side
>>>loads. "Jim beam" may well have quoted selectively to obscure the context.
>>>Furthermore, even if Jobst exaggerated at one point, it's simply sophistry
>>>to ignore the qualifying remarks he makes at other points in the book.
>>
>> Dear Gary,
>>
>> You're interested in textual references? How nice! There's nothing
>> like a good discussion of the vexing problem of how to cut and paste
>> together a version of Hamlet that combines the various quartos
>> (published without Shakespeare's consent during his lifetime) with the
>> version found in the First Folio of 1623, published also without his
>> consent, seven years after his death. Unlike Macbeth, for which we
>> have only the First Folio version and thus no scholarly debate--
>>
>> Oh, you're only interested in "The Bicycle Wheel"?
>>
>> Well, there are three English editions of Jobst's book, plus one in
>> German that we will ignore.
>>
>> The two later editions add a little material and subtract a little
>> material, but they mainly reword things, often sentence by sentence.
>>
>> This inch-by-inch rephrasing makes it horribly difficult to find a
>> particular passage.
>>
>> Even worse from a scholarly point of view, the theoretical material in
>> the first part is often repeated in the second practical part, so you
>> may be looking at the wrong end of the book.
>>
>> Frequently the reader hits an it's-explained-elsewhere comment, but
>> there's no page number given and no index.
>>
>> (A scanned and searchable version obtained from unethical sources
>> helps immensely. Anyone willing to profit from piracy is welcome to
>> ask me to search for a phrase from the 3rd edition, since it only
>> takes a few moments.)
>>
>> To be fair, Jobst was no more writing for scholars than Shakespeare
>> was, and Jim faces a hideous scholarly task if he wants to footnote
>> properly.
>>
>> ***
>>
>> Here's the first edition (1981, 1983), illustrated by Sherry
>> Sheffield-Boulton, p. 78:
>>
>> SPOKE TENSION
>>
>> The correct tension for a wheel must be a balance between rim strength
>> and wheel stability. The spokes should be as tight as the rim permits
>> for maxium strength. However, for practical reasonss the spokes should
>> be slightly looser than this because at the maximum tension, the
>> failure of one spoke may destroy the rim.
>>
>> ***
>>
>> Here's the second edition (1981, 1983, 1988, 7th printing 1990),
>> illustrated by Sherry Sheffield Boulton (no dash), p. 76:
>>
>> SPOKE TENSION
>>
>> The correct tension for a wheel is a balance between rim strength and
>> wheel stability. For greatest strength, spokes should be as tight as
>> the rim permits. In practice, however, spokes should be slightly
>> looser because when they are at the limit, failure of a single spoke
>> can severely deform the rim.
>>
>> ***
>>
>> And here's the third edition (1993), illustrated by Sherry Sheffield
>> (no Boulton), page 71:
>>
>> SPOKE TENSION
>>
>> With tensioned wires as spokes, the wheel can support loads only to
>> the point where its spokes become loose. At this point the wheel will
>> collapse. Therefore, for greatest strength, spokes must be as tight as
>> the rim permits. . . .
>>
>> [skip the rest of the paragraph and jump ~80 words to where the next
>> sentence has been moved]
>>
>> In practice, however, spokes should be slightly looser than the
>> maximum the rim can sustain, because at maximum tension, failure of a
>> single spoke can severely deform the rim.
>>
>> ***
>>
>> I defy anyone to find a more trivial example of the trivial changes
>> between the three editions than the illustrator's name (which may have
>> been far from trivial to her).
>>
>> Anyway, there's the text and the page numbers and some explanation why
>> quoting from various editions of "The Bicycle Wheel" is something that
>> only the truly pedantic can enjoy.
>>
>> Cheers,
>>
>> Carl Fogel
>
>Carl,
>Thanks for supplying the quotation, but I do think you exaggerate the
>difficulties "jim beam" faced. He said in an earlier post that he took the
>quotation from the third edition and should have been able to supply a
>page.
>
>In any event, judging from the discussion taking place between Jobst and
>Peter Cole right now, I'm getting the impression that I've once again
>allowed my zeal to expose jim beam's nonsense take me beyond my knowledge.
>I'm going to try to be humble for awhile.
Dear Gary,
To be fair to Jim, you've got the page number and two previous
variations of the same section that you asked for when you wrote:
"I wouldn't go so far as to call it an exaggeration until 'jim beam'
supplies a page reference (he's ignored my request for that). Jobst is
usually careful to say that a slack wheel is vulnerable primarily to
side loads. 'Jim beam' may well have quoted selectively to obscure the
context."
"Furthermore, even if Jobst exaggerated at one point, it's simply
sophistry to ignore the qualifying remarks he makes at other points in
the book."
It looks like an accurate, in-context quote. There is no mention of
side loads on those pages. If people want to argue that Jim Beam is
missing something, then it's up to them to provide the quote or
context that they imply he is concealing.
So far, they haven't.
I'm not concerned with the physics, just the claims from various
obviously prejudiced posters that someone who quotes specifically and
accurately and apparently in context is not doing so, without any
explanation or equally specific quotations refuting the point. Perhaps
less irritated replies would have explained things better.
I appreciate your frank admission that you may have let your zeal to
squabble with Jim get the best of you--I hope that I can admit as much
when I find myself in a similar situation.
Cheers,
Carl Fogel
|
| | | | |
Date: 21 Jul 2007 16:36:17
From: Tom \Johnny Sunset\ Sherman
Subject: Re: spoke tension
|
carlfogel@comcast.net aka Carl Fogel wrote:
> ...
> I appreciate your frank admission that you may have let your zeal to
> squabble with Jim get the best of you--I hope that I can admit as much
> when I find myself in a similar situation....
Past history indicates...
--
Tom Sherman - Holstein-Friesland Bovinia
The weather is here, wish you were beautiful
--
Posted via a free Usenet account from http://www.teranews.com
|
| | |
Date: 17 Jul 2007 18:47:37
From: Peter Cole
Subject: Re: spoke tension
|
Johnny Sunset aka Tom Sherman wrote:
> Mark Felber wrote:
>> Could someone recommend the proper spoke tension for a rear wheel
>> built with a Velocity Aerohead OC rim?
>
> JB says tension as high as the rim will bear without taking a "taco" or
> "potato chip" shape; however, jb says tension only as high as the
> manufacturer's recommendation, or the rim will crack around the spoke hole.
>
> LET THE BATTLE BEGIN!
>
That's not really what Jobst says. It's what jim beam says Jobst says,
which are usually two (often very) different things. I guess you didn't
read the book, either.
|
| | | |
Date: 17 Jul 2007 21:36:21
From: jim beam
Subject: Re: spoke tension
|
Peter Cole wrote:
> Johnny Sunset aka Tom Sherman wrote:
>> Mark Felber wrote:
>>> Could someone recommend the proper spoke tension for a rear wheel
>>> built with a Velocity Aerohead OC rim?
>>
>> JB says tension as high as the rim will bear without taking a "taco"
>> or "potato chip" shape; however, jb says tension only as high as the
>> manufacturer's recommendation, or the rim will crack around the spoke
>> hole.
>>
>> LET THE BATTLE BEGIN!
>>
>
> That's not really what Jobst says. It's what jim beam says Jobst says,
> which are usually two (often very) different things. I guess you didn't
> read the book, either.
"as high as the rim can bear" is what jobst says on this group.
"spokes must be as tight as the rim permits" is what he says in "the
book". [3rd edition.]
either way, he equates increasing spoke tension with increasing wheel
strength: "a wheel with spoke tension near the limit of rim strength can
support large loads easily" - which is untrue, misleading and reveals
gross misunderstanding.
|
| | | | |
Date: 18 Jul 2007 05:03:42
From:
Subject: Re: spoke tension
|
http://www.jimbeam.com/beam/default.aspx? writes:
>>>> Could someone recommend the proper spoke tension for a rear wheel
>>>> built with a Velocity Aerohead OC rim?
>>> JB says tension as high as the rim will bear without taking a
>>> "taco" or "potato chip" shape; however, jb says tension only as
>>> high as the manufacturer's recommendation, or the rim will crack
>>> around the spoke hole.
>>> LET THE BATTLE BEGIN!
>> That's not really what Jobst says. It's what jim beam says Jobst
>> says, which are usually two (often very) different things. I guess
>> you didn't read the book, either.
> "as high as the rim can bear" is what jobst says on this group.
> "spokes must be as tight as the rim permits" is what he says in "the
> book". [3rd edition.]
> either way, he equates increasing spoke tension with increasing
> wheel strength: "a wheel with spoke tension near the limit of rim
> strength can support large loads easily" - which is untrue,
> misleading and reveals gross misunderstanding.
I think such statements need a bit of evidence to be credible.
A wire spoked bicycle wheel can carry loads up to the point where its
spokes become slack from compression as they pass the load point on
the road. The looser the spokes the more easily this occurs and
conversely the tighter the spoke the less this occurs.
I have ridden many 100k miles with wheels tensioned as described
without needing to re-true them or to replace cracked rims. These
have been socketed tubular rims (Fiamme, Super Champion, and Mavic)
and Super Champion "Gentleman" and Mavic MA-2 clincher rims. I still
ride the latter as do most of my fellow riders, ones who do not see
themselves as professional like racers..
When riding rough roads such as described in rec.bicycles.rides "Last
chance road", I and my bikie friends wonder if the light weight "with
it" crowd ever experience roads that are demanding on 36-spoke wheels.
http://tinyurl.com/2uc6tb
Dings in rims also come from insufficient inflation, a parallel to
insufficient spoke tension in supporting loads.
http://geocities.com/rayhosler/slideshow.html
Ride bike!
Jobst Brandt
|
| | | | | |
Date: 17 Jul 2007 22:33:59
From: jim beam
Subject: Re: spoke tension
|
jobst.brandt@stanfordalumni.org wrote:
> http://www.jimbeam.com/beam/default.aspx? writes:
>
>>>>> Could someone recommend the proper spoke tension for a rear wheel
>>>>> built with a Velocity Aerohead OC rim?
>
>>>> JB says tension as high as the rim will bear without taking a
>>>> "taco" or "potato chip" shape; however, jb says tension only as
>>>> high as the manufacturer's recommendation, or the rim will crack
>>>> around the spoke hole.
>
>>>> LET THE BATTLE BEGIN!
>
>>> That's not really what Jobst says. It's what jim beam says Jobst
>>> says, which are usually two (often very) different things. I guess
>>> you didn't read the book, either.
>
>> "as high as the rim can bear" is what jobst says on this group.
>
>> "spokes must be as tight as the rim permits" is what he says in "the
>> book". [3rd edition.]
>
>> either way, he equates increasing spoke tension with increasing
>> wheel strength: "a wheel with spoke tension near the limit of rim
>> strength can support large loads easily" - which is untrue,
>> misleading and reveals gross misunderstanding.
>
> I think such statements need a bit of evidence to be credible.
>
> A wire spoked bicycle wheel can carry loads up to the point where its
> spokes become slack from compression as they pass the load point on
> the road. The looser the spokes the more easily this occurs and
> conversely the tighter the spoke the less this occurs.
as discussed on several prior occasions, you are only considering the
spokes, not the rim. increasing spoke tension increases circumferential
rim compression. but you miss the point that as the rim's compression
rises, its load capacity decreases.
let's assume an aluminum beam has the same tensile strength as it does
compression. let's say that it yields at [pick a number] +/- 100Mpa.
in plain bending, the compressive side yields at the same time as the
tensile side - when this limit is reached. now, compress the beam
longitudinally at say 50Mpa, i.e. superimpose a stress on it. the
tensile side of the beam can now support 100 + 50 = 150Mpa before yield.
but the compressive side can only support 100 - 50 = 50Mpa. so if i
bend it now, the beam will start to yield supporting only half the load
it did before.
with materials with no tensile strength like concrete, you "borrow" from
the material's [ample] compressive strength to give it pseudo tensile
strength. but with a material as strong in compression as tension, like
an aluminum bike rim, that's simply counter-productive.
in your book, you also argue that rims collapse as soon as spokes go
slack go slack....
http://www.flickr.com/photos/38636024@N00/417157612/
writing a book is one thing. understanding what to put in it is quite
another.
>
> I have ridden many 100k miles with wheels tensioned as described
> without needing to re-true them or to replace cracked rims. These
> have been socketed tubular rims (Fiamme, Super Champion, and Mavic)
> and Super Champion "Gentleman" and Mavic MA-2 clincher rims. I still
> ride the latter as do most of my fellow riders, ones who do not see
> themselves as professional like racers..
>
> When riding rough roads such as described in rec.bicycles.rides "Last
> chance road", I and my bikie friends wonder if the light weight "with
> it" crowd ever experience roads that are demanding on 36-spoke wheels.
>
> http://tinyurl.com/2uc6tb
>
> Dings in rims also come from insufficient inflation, a parallel to
> insufficient spoke tension in supporting loads.
>
> http://geocities.com/rayhosler/slideshow.html
>
> Ride bike!
red herring.
|
| | | | | | |
Date: 18 Jul 2007 13:28:47
From: Peter Cole
Subject: Re: spoke tension
|
jim beam wrote:
> jobst.brandt@stanfordalumni.org wrote:
>> http://www.jimbeam.com/beam/default.aspx? writes:
>>
>>>>>> Could someone recommend the proper spoke tension for a rear wheel
>>>>>> built with a Velocity Aerohead OC rim?
>>
>>>>> JB says tension as high as the rim will bear without taking a
>>>>> "taco" or "potato chip" shape; however, jb says tension only as
>>>>> high as the manufacturer's recommendation, or the rim will crack
>>>>> around the spoke hole.
>>
>>>>> LET THE BATTLE BEGIN!
>>
>>>> That's not really what Jobst says. It's what jim beam says Jobst
>>>> says, which are usually two (often very) different things. I guess
>>>> you didn't read the book, either.
>>
>>> "as high as the rim can bear" is what jobst says on this group.
>>
>>> "spokes must be as tight as the rim permits" is what he says in "the
>>> book". [3rd edition.]
>>
>>> either way, he equates increasing spoke tension with increasing
>>> wheel strength: "a wheel with spoke tension near the limit of rim
>>> strength can support large loads easily" - which is untrue,
>>> misleading and reveals gross misunderstanding.
>>
>> I think such statements need a bit of evidence to be credible.
>>
>> A wire spoked bicycle wheel can carry loads up to the point where its
>> spokes become slack from compression as they pass the load point on
>> the road. The looser the spokes the more easily this occurs and
>> conversely the tighter the spoke the less this occurs.
>
> as discussed on several prior occasions, you are only considering the
> spokes, not the rim. increasing spoke tension increases circumferential
> rim compression. but you miss the point that as the rim's compression
> rises, its load capacity decreases.
>
> let's assume an aluminum beam has the same tensile strength as it does
> compression. let's say that it yields at [pick a number] +/- 100Mpa. in
> plain bending, the compressive side yields at the same time as the
> tensile side - when this limit is reached. now, compress the beam
> longitudinally at say 50Mpa, i.e. superimpose a stress on it. the
> tensile side of the beam can now support 100 + 50 = 150Mpa before yield.
> but the compressive side can only support 100 - 50 = 50Mpa. so if i
> bend it now, the beam will start to yield supporting only half the load
> it did before.
>
> with materials with no tensile strength like concrete, you "borrow" from
> the material's [ample] compressive strength to give it pseudo tensile
> strength. but with a material as strong in compression as tension, like
> an aluminum bike rim, that's simply counter-productive.
You simply can't explain something as complex as a spoked wheel with
this homespun approach. It's difficult to put in layman's terms, but the
math is all worked out. Perhaps you could break down and actually read
Jobst's book or Gavin's paper (which are completely consistent).
Jobst won't rebut your rantings because (I assume) you're such an
abusive SOB. I can't blame him for that, but somebody has to call your
BS. Of course many have in the past, but you just take a breather &
start up again as if nothing happened.
Analysis of a spoked wheel is a complex engineering exercise, the
principles are not intuitively obvious, otherwise Gavin wouldn't have
filled several pages with math and Jobst with FEA results. Hand waving
doesn't cut it, even with the gratuitous introduction of a couple of
numbers.
Inaccurately paraphrasing a book you've never read doesn't help, either.
|
| | | | | | | |
Date: 18 Jul 2007 21:48:33
From: jim beam
Subject: Re: spoke tension
|
Peter Cole wrote:
> jim beam wrote:
>> jobst.brandt@stanfordalumni.org wrote:
>>> http://www.jimbeam.com/beam/default.aspx? writes:
>>>
>>>>>>> Could someone recommend the proper spoke tension for a rear wheel
>>>>>>> built with a Velocity Aerohead OC rim?
>>>
>>>>>> JB says tension as high as the rim will bear without taking a
>>>>>> "taco" or "potato chip" shape; however, jb says tension only as
>>>>>> high as the manufacturer's recommendation, or the rim will crack
>>>>>> around the spoke hole.
>>>
>>>>>> LET THE BATTLE BEGIN!
>>>
>>>>> That's not really what Jobst says. It's what jim beam says Jobst
>>>>> says, which are usually two (often very) different things. I guess
>>>>> you didn't read the book, either.
>>>
>>>> "as high as the rim can bear" is what jobst says on this group.
>>>
>>>> "spokes must be as tight as the rim permits" is what he says in "the
>>>> book". [3rd edition.]
>>>
>>>> either way, he equates increasing spoke tension with increasing
>>>> wheel strength: "a wheel with spoke tension near the limit of rim
>>>> strength can support large loads easily" - which is untrue,
>>>> misleading and reveals gross misunderstanding.
>>>
>>> I think such statements need a bit of evidence to be credible.
>>>
>>> A wire spoked bicycle wheel can carry loads up to the point where its
>>> spokes become slack from compression as they pass the load point on
>>> the road. The looser the spokes the more easily this occurs and
>>> conversely the tighter the spoke the less this occurs.
>>
>> as discussed on several prior occasions, you are only considering the
>> spokes, not the rim. increasing spoke tension increases
>> circumferential rim compression. but you miss the point that as the
>> rim's compression rises, its load capacity decreases.
>>
>> let's assume an aluminum beam has the same tensile strength as it does
>> compression. let's say that it yields at [pick a number] +/- 100Mpa.
>> in plain bending, the compressive side yields at the same time as the
>> tensile side - when this limit is reached. now, compress the beam
>> longitudinally at say 50Mpa, i.e. superimpose a stress on it. the
>> tensile side of the beam can now support 100 + 50 = 150Mpa before
>> yield. but the compressive side can only support 100 - 50 = 50Mpa.
>> so if i bend it now, the beam will start to yield supporting only half
>> the load it did before.
>>
>> with materials with no tensile strength like concrete, you "borrow"
>> from the material's [ample] compressive strength to give it pseudo
>> tensile strength. but with a material as strong in compression as
>> tension, like an aluminum bike rim, that's simply counter-productive.
>
> You simply can't explain something as complex as a spoked wheel with
> this homespun approach. It's difficult to put in layman's terms, but the
> math is all worked out. Perhaps you could break down and actually read
> Jobst's book or Gavin's paper (which are completely consistent).
>
> Jobst won't rebut your rantings because (I assume) you're such an
> abusive SOB. I can't blame him for that, but somebody has to call your
> BS. Of course many have in the past, but you just take a breather &
> start up again as if nothing happened.
>
> Analysis of a spoked wheel is a complex engineering exercise, the
> principles are not intuitively obvious, otherwise Gavin wouldn't have
> filled several pages with math and Jobst with FEA results. Hand waving
> doesn't cut it, even with the gratuitous introduction of a couple of
> numbers.
>
> Inaccurately paraphrasing a book you've never read doesn't help, either.
finite element analysis is examining small elements. any small element
when loaded above yield will, well, yield! i don't care how you try to
obscure the facts with ad hominem. the fact is, any single element when
loaded above yield will permanently deform. and in a bike wheel, that
is failure. i've broken the facts down into the simplest possible
elements. dispute them. don't retreat into b.s. analyze.
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| | | | | | | | |
Date: 19 Jul 2007 17:09:07
From: Peter Cole
Subject: Re: spoke tension
|
jim beam wrote:
> i don't care how you try to
> obscure the facts with ad hominem.
OK, now I've heard it all.
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Date: 20 Jul 2007 18:56:31
From: jim beam
Subject: Re: spoke tension
|
Peter Cole wrote:
> jim beam wrote:
>
>> i don't care how you try to obscure the facts with ad hominem.
>
> OK, now I've heard it all.
>
that's not analysis. address the points raised.
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Date: 20 Jul 2007 22:26:04
From: Peter Cole
Subject: Re: spoke tension
|
jim beam wrote:
> Peter Cole wrote:
>> jim beam wrote:
>>
>>> i don't care how you try to obscure the facts with ad hominem.
>>
>> OK, now I've heard it all.
>>
>
> that's not analysis. address the points raised.
I did. You didn't raise any "points", you just made a brief hand waving
description of a bicycle wheel (a wrong one, as it turns out). It's more
complex than that, but you can't/won't read the material.
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Date: 20 Jul 2007 19:51:02
From: jim beam
Subject: Re: spoke tension
|
Peter Cole wrote:
> jim beam wrote:
>> Peter Cole wrote:
>>> jim beam wrote:
>>>
>>>> i don't care how you try to obscure the facts with ad hominem.
>>>
>>> OK, now I've heard it all.
>>>
>>
>> that's not analysis. address the points raised.
>
> I did. You didn't raise any "points", you just made a brief hand waving
> description of a bicycle wheel (a wrong one, as it turns out). It's more
> complex than that, but you can't/won't read the material.
each element can be examined in isolation just as i describe. seeking
refuge in complexity is just hypocritical "hand waving".
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Date: 18 Jul 2007 00:38:35
From: Johnny Sunset aka Tom Sherman
Subject: Re: spoke tension
|
"jim beam" ? wrote:
> ...
> in your book, you also argue that rims collapse as soon as spokes go
> slack go slack....
> http://www.flickr.com/photos/38636024@N00/417157612/
How far did you ride on that wheel?
--
Tom Sherman - Holstein-Friesland Bovinia
The weather is here, wish you were beautiful
--
Posted via a free Usenet account from http://www.teranews.com
|
| | | | | | | |
Date: 18 Jul 2007 06:02:26
From: jim beam
Subject: Re: spoke tension
|
Johnny Sunset aka Tom Sherman wrote:
> "jim beam" ? wrote:
>> ...
>> in your book, you also argue that rims collapse as soon as spokes go
>> slack go slack....
>> http://www.flickr.com/photos/38636024@N00/417157612/
>
> How far did you ride on that wheel?
>
as far as i could without the tensiometer falling off... wise guy.
how about you address the point of the posting: "...the wheel can
support loads only to the point where its spokes become loose. at this
point the wheel will collapse." jobst brandt. "the book". 3rd edition.
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Date: 18 Jul 2007 19:31:45
From: Johnny Sunset aka Tom Sherman
Subject: Re: spoke tension
|
"jim beam" ? wrote:
> Johnny Sunset aka Tom Sherman wrote:
>> "jim beam" ? wrote:
>>> ...
>>> in your book, you also argue that rims collapse as soon as spokes go
>>> slack go slack....
>>> http://www.flickr.com/photos/38636024@N00/417157612/
>>
>> How far did you ride on that wheel?
>>
> as far as i could without the tensiometer falling off... wise guy.
>
> how about you address the point of the posting: "...the wheel can
> support loads only to the point where its spokes become loose. at this
> point the wheel will collapse." jobst brandt. "the book". 3rd edition.
Would "jim beam's" wheel with missing spokes collapse if ridden? If so,
JB is right (for all practical purposes) and jb is wrong.
--
Tom Sherman - Holstein-Friesland Bovinia
The weather is here, wish you were beautiful
--
Posted via a free Usenet account from http://www.teranews.com
|
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Date: 18 Jul 2007 21:43:17
From: jim beam
Subject: Re: spoke tension
|
Johnny Sunset aka Tom Sherman wrote:
> "jim beam" ? wrote:
>> Johnny Sunset aka Tom Sherman wrote:
>>> "jim beam" ? wrote:
>>>> ...
>>>> in your book, you also argue that rims collapse as soon as spokes go
>>>> slack go slack....
>>>> http://www.flickr.com/photos/38636024@N00/417157612/
>>>
>>> How far did you ride on that wheel?
>>>
>> as far as i could without the tensiometer falling off... wise guy.
>>
>> how about you address the point of the posting: "...the wheel can
>> support loads only to the point where its spokes become loose. at
>> this point the wheel will collapse." jobst brandt. "the book". 3rd
>> edition.
>
> Would "jim beam's" wheel with missing spokes collapse if ridden? If so,
> JB is right (for all practical purposes) and jb is wrong.
>
i've ridden a slack spoked wheel so see if it works. and it does. and
you can google this group for my experience with a friend's slack spoked
mtb wheel. you should try it too. your only problem is spoke nipples
unscrewing.
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Date: 18 Jul 2007 00:16:08
From: Johnny Sunset aka Tom Sherman
Subject: Re: spoke tension
|
jobst.brandt@stanfordalumni.org aka Jobst Brandt wrote:
> ...
> Dings in rims also come from insufficient inflation...
During the Weimar Republic era, German riders found their rims
impervious to damage from potholes and other impacts.
--
Tom Sherman - Holstein-Friesland Bovinia
The weather is here, wish you were beautiful
--
Posted via a free Usenet account from http://www.teranews.com
|
| | | |
Date: 17 Jul 2007 20:42:57
From: Johnny Sunset aka Tom Sherman
Subject: Re: spoke tension
|
Peter Cole wrote:
> Johnny Sunset aka Tom Sherman wrote:
>> Mark Felber wrote:
>>> Could someone recommend the proper spoke tension for a rear wheel
>>> built with a Velocity Aerohead OC rim?
>>
>> JB says tension as high as the rim will bear without taking a "taco"
>> or "potato chip" shape; however, jb says tension only as high as the
>> manufacturer's recommendation, or the rim will crack around the spoke
>> hole.
>>
>> LET THE BATTLE BEGIN!
>>
>
> That's not really what Jobst says. It's what jim beam says Jobst says,
> which are usually two (often very) different things. I guess you didn't
> read the book, either.
Well, I actually have read "The Bicycle Wheel" (but not recently). So
much for assumptions.
Do you deny that Jobst Brandt has stated that ONE of the methods for
determining maximum tension is that if the rim does NOT stay true when
stress relieving [1], the spokes are too tight?
[1] Not what happens according to jb.
--
Tom Sherman - Holstein-Friesland Bovinia
The weather is here, wish you were beautiful
--
Posted via a free Usenet account from http://www.teranews.com
|
| | | | |
Date: 18 Jul 2007 03:12:24
From: mark
Subject: Re: spoke tension
|
Johnny Sunset aka Tom Sherman wrote:
> Do you deny that Jobst Brandt has stated that ONE of the methods for
> determining maximum tension is that if the rim does NOT stay true when
> stress relieving [1], the spokes are too tight?
My (third printing, 1985) copy of The Bicycle wheel says:
"When maximum tension is reached the wheel will not remain true after
stress relieving. This tension should be approached carefully to avoid
rim damage. When the wheel begins to deform upon stress relieving, all
spokes should be loosened half a turn and the wheel re-trued."
mark
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| | | | | |
Date: 18 Jul 2007 06:05:53
From: jim beam
Subject: Re: spoke tension
|
mark wrote:
>
>
> Johnny Sunset aka Tom Sherman wrote:
>
>> Do you deny that Jobst Brandt has stated that ONE of the methods for
>> determining maximum tension is that if the rim does NOT stay true when
>> stress relieving [1], the spokes are too tight?
>
> My (third printing, 1985) copy of The Bicycle wheel says:
>
> "When maximum tension is reached the wheel will not remain true after
> stress relieving. This tension should be approached carefully to avoid
> rim damage. When the wheel begins to deform upon stress relieving, all
> spokes should be loosened half a turn and the wheel re-trued."
random and arbitrary rubbish. "hey, how much load can that old wooden
bridge support? dunno, let's drive across it and find out."
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Date: 18 Jul 2007 00:59:04
From: Johnny Sunset aka Tom Sherman
Subject: Re: spoke tension
|
Mark Felber wrote:
>
>
> Johnny Sunset aka Tom Sherman wrote:
>
>> Do you deny that Jobst Brandt has stated that ONE of the methods for
>> determining maximum tension is that if the rim does NOT stay true when
>> stress relieving [1], the spokes are too tight?
>
> My (third printing, 1985) copy of The Bicycle wheel says:
>
> "When maximum tension is reached the wheel will not remain true after
> stress relieving. This tension should be approached carefully to avoid
> rim damage. When the wheel begins to deform upon stress relieving, all
> spokes should be loosened half a turn and the wheel re-trued."
Exactly the passage I was referring to (from memory).
--
Tom Sherman - Holstein-Friesland Bovinia
The weather is here, wish you were beautiful
--
Posted via a free Usenet account from http://www.teranews.com
|
| | | | | | |
Date: 18 Jul 2007 13:02:45
From: Peter Cole
Subject: Re: spoke tension
|
Johnny Sunset aka Tom Sherman wrote:
> Mark Felber wrote:
>>
>>
>> Johnny Sunset aka Tom Sherman wrote:
>>
>>> Do you deny that Jobst Brandt has stated that ONE of the methods for
>>> determining maximum tension is that if the rim does NOT stay true
>>> when stress relieving [1], the spokes are too tight?
>>
>> My (third printing, 1985) copy of The Bicycle wheel says:
>>
>> "When maximum tension is reached the wheel will not remain true after
>> stress relieving. This tension should be approached carefully to avoid
>> rim damage. When the wheel begins to deform upon stress relieving, all
>> spokes should be loosened half a turn and the wheel re-trued."
>
> Exactly the passage I was referring to (from memory).
>
Your paraphrase left out a couple of critical points, plus the overall
context.
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| | | | | | | |
Date: 18 Jul 2007 19:27:31
From: Johnny Sunset aka Tom Sherman
Subject: Re: spoke tension
|
Peter Cole wrote:
> Johnny Sunset aka Tom Sherman wrote:
>> Mark Felber wrote:
>>>
>>>
>>> Johnny Sunset aka Tom Sherman wrote:
>>>
>>>> Do you deny that Jobst Brandt has stated that ONE of the methods for
>>>> determining maximum tension is that if the rim does NOT stay true
>>>> when stress relieving [1], the spokes are too tight?
>>>
>>> My (third printing, 1985) copy of The Bicycle wheel says:
>>>
>>> "When maximum tension is reached the wheel will not remain true after
>>> stress relieving. This tension should be approached carefully to
>>> avoid rim damage. When the wheel begins to deform upon stress
>>> relieving, all spokes should be loosened half a turn and the wheel
>>> re-trued."
>>
>> Exactly the passage I was referring to (from memory).
>>
>
> Your paraphrase left out a couple of critical points, plus the overall
> context.
Whoosh!
I was chumming the water's of rec.bicycles.tech.
--
Tom Sherman - Holstein-Friesland Bovinia
The weather is here, wish you were beautiful
--
Posted via a free Usenet account from http://www.teranews.com
|
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Date: 17 Jul 2007 23:42:38
From:
Subject: Re: spoke tension
|
On Wed, 18 Jul 2007 03:12:24 GMT, mark <markfelber@earthlink.net >
wrote:
>
>
>Johnny Sunset aka Tom Sherman wrote:
>
>> Do you deny that Jobst Brandt has stated that ONE of the methods for
>> determining maximum tension is that if the rim does NOT stay true when
>> stress relieving [1], the spokes are too tight?
>
>My (third printing, 1985) copy of The Bicycle wheel says:
>
>"When maximum tension is reached the wheel will not remain true after
>stress relieving. This tension should be approached carefully to avoid
>rim damage. When the wheel begins to deform upon stress relieving, all
>spokes should be loosened half a turn and the wheel re-trued."
>
>mark
Dear Mark,
I posted the following earlier in reply to Peter Cole, but it doesn't
seem to show up outside of cyclingforums, so here it is again. I'm
tacking it on to your post, since they're related and I can't get at
earlier posts, with Google down and cyclingforums not propagating. The
lengthy quote is from the 3rd edition of 1993, rather than the 3rd
printing of an earlier edition.
Here's what Jobst wrote:
FINDING THE RIGHT TENSION
The following method works well in determining proper spoke tension
for conventional road rims of up to 430 grams with 36 spokes. Tighten
all the spokes a quarter turn at a time, starting at the valve stem
hole. Once a distinct tone can be made by plucking, and spokes are not
easily squeezed together by grasping them in pairs, it is time to
check tension. After each round of tightening, test the tension by
stress relieving. If the wheel becomes untrue in two large waves
during stress relieving, the maximum, safe tension has been exceeded.
Approach this tension carefully to avoid major rim distortions. When
the wheel loses alignment from stress relieving, loosen all spokes a
half turn before retruing the wheel.
Stress relieving, discussed in a following section, increases tension
enough to overload the rim if the spokes are too tight. A strong and
safe wheel should be able to withstand about a ten percent overload
without damage. Note that tightening all spokes of an offset rear
wheel will move the rim away from the right side as described under
Wheels with Multiple Sprockets (page 100). Check centering and radial
and lateral alignment again. Only small corrections, if any, should be
required.
With large cross section mountain bike and deep section aero rims the
tension of 36 spokes may not exceed the strength of the rim. For such
heavy rims and conventional road rims using fewer than 32 spokes,
tensioning is usually at the limit when the nipples can no longer be
tightened easily.
--"The Bicycle Wheel," 3rd edition, p. 105
It should be noted that wheels are usually built with no tire.
Inflating a 700c tire to 120 psi on a typical modern box-section rim
causes the tire to constrict like a python around the rim and reduces
99 kgf spoke tension around ~15%:
http://www.geocities.com/dianne_1234/bikes/tension-inflation/tension-inflation.htm
Thus many road wheels are at lower practical tension than their
builders realize.
On the other hand, inflating a tire on a wide no-box section rim can
_increase_ spoke tension. The effect of the tire constricting the long
way around the rim is swamped by the tire bulging sideways, spreading
the vee of the rim, and drawing the spokes away from the hub:
http://groups.google.com/group/rec.bicycles.tech/msg/81bd0e13a9a0797e
Cheers,
Carl Fogel
|
| | | | | | |
Date: 18 Jul 2007 13:41:02
From: mark
Subject: Re: spoke tension
|
Interesting, and thanks for the update. It might be time for a new copy
of "The Bicycle Wheel".
mark
|
| |
Date: 17 Jul 2007 12:16:16
From: Qui si parla Campagnolo
Subject: Re: spoke tension
|
On Jul 16, 11:19 pm, mark <markfel...@earthlink.net > wrote:
> Could someone recommend the proper spoke tension for a rear wheel built
> with a Velocity Aerohead OC rim?
>
> TIA,
>
> mark
100 kgf for the right side. If true, round, dished..the left side
tension will take care of itself.
|
| | |
Date: 17 Jul 2007 09:00:51
From: Tim McNamara
Subject: Re: spoke tension
|
In article <1184674576.251361.327470@m37g2000prh.googlegroups.com >,
Qui si parla Campagnolo <peter@vecchios.com > wrote:
> On Jul 16, 11:19 pm, mark <markfel...@earthlink.net> wrote:
> > Could someone recommend the proper spoke tension for a rear wheel
> > built with a Velocity Aerohead OC rim?
> >
>
> 100 kgf for the right side.
Which is pretty much the standard number used for the drive side of the
rear wheel and both sides of the front wheel for just about any wheel
with a normal number of spokes (32-36). Except for Mavic who recommend
95 kgf, according to previously published information.
|
| | |
Date: 17 Jul 2007 12:26:13
From: mark
Subject: Re: spoke tension
|
Thank you.
mark
Qui si parla Campagnolo wrote:
> On Jul 16, 11:19 pm, mark <markfel...@earthlink.net> wrote:
>> Could someone recommend the proper spoke tension for a rear wheel built
>> with a Velocity Aerohead OC rim?
>>
>> TIA,
>>
>> mark
>
> 100 kgf for the right side. If true, round, dished..the left side
> tension will take care of itself.
>
|
|
