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#21
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Tied and soldered spokes.
Ian Smith wrote:
On Sat, 21 Nov 2009 20:16:35 +0000, Naqerj wrote: Ian Smith wrote: On Fri, 20 Nov, wrote: On Nov 21, 3:38 am, Ian Smith wrote: Out of interest, however, has anyone ever seen a purely radial buckle on a bicycle wheel? I've dented a rim wall (think severe pinch flat territory). Does that count? I don't think so. In fact, it would tend to demonstrate the case that they don't happen - you can hit the rim hard enough to cause plastic material failure and no radial buckle occurred. Like James, I've dented a rim wall but without buckling the rim as a whole - I have seen a radial buckle, but in a motor cycle wheel. I reckon it is possible to radial buckle a wheel but you have to hit it very hard indeed. The other thing with a pedal cycle wheel is that to get a purely radial buckle you'd not only have to hit it very hard, but also dead square, otherwise it will buckle laterally as well. Then you could argue for days about whether that counts as a radial buckle. It would be relatively simple to determine whether it was a radial buckle - you'd need to plot distance of rim from hub centre and see if you had an elastic-type variation from constant, then destress the wheel and see if it recovers. Every lateral buckle I've seen on a bicycle wheel looks like a near-enough purely lateral buckle - the 'pringles' look. I don't think you can load a bicycle wheel on a bicycle to a level that causes a radial buckle without first triggering either a plastic failure, or a lateral buckle. Ah, we're not talking about quite the same thing, I think. The motor cycle wheel I saw had a plastic failure of the rim - the rim ended up heart-shaped. -- Andrew |
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#22
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Tied and soldered spokes.
thirty-six wrote:
On 22 Nov, 18:08, Ian Smith wrote: Likewise, I think you'll always get a lateral buckle from a wheel before you get a radial buckle. If always, then wheels have too poor a lateral stability. The other way round: it that the radial stability than is greater than strictly necessary, rather than lateral stability being poor. Even lateral stability is greater than necessary - a bicycle wheel works perfectly well in a tricycle, which subjects it to more lateral force than a bicycle does. The high proportion of radial stability compared to lateral is pretty much determined by the shape of the space the wheel has to fit into. -- Andrew |
#23
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Tied and soldered spokes.
On 23 Nov, 22:29, Naqerj wrote:
Ian Smith wrote: On Sat, 21 Nov 2009 20:16:35 +0000, Naqerj wrote: *Ian Smith wrote: On Fri, 20 Nov, wrote: *On Nov 21, 3:38 am, Ian Smith wrote: Out of interest, however, has anyone ever seen a purely radial buckle on a bicycle wheel? *I've dented a rim wall (think severe pinch flat territory). Does *that count? I don't think so. *In fact, it would tend to demonstrate the case that they don't happen - you can hit the rim hard enough to cause plastic material failure and no radial buckle occurred. *Like James, I've dented a rim wall but without buckling the rim as a *whole - I have seen a radial buckle, but in a motor cycle wheel. *I *reckon it is possible to radial buckle a wheel but you have to hit it *very hard indeed. *The other thing with a pedal cycle wheel is that to *get a purely radial buckle you'd not only have to hit it very hard, but *also dead square, otherwise it will buckle laterally as well. *Then you *could argue for days about whether that counts as a radial buckle. It would be relatively simple to determine whether it was a radial buckle - you'd need to plot distance of rim from hub centre and see if you had an elastic-type variation from constant, then destress the wheel and see if it recovers. Every lateral buckle I've seen on a bicycle wheel looks like a near-enough purely lateral buckle - the 'pringles' look. *I don't think you can load a bicycle wheel on a bicycle to a level that causes a radial buckle without first triggering either a plastic failure, or a lateral buckle. Ah, we're not talking about quite the same thing, I think. *The motor cycle wheel I saw had a plastic failure of the rim - the rim ended up heart-shaped. Which doesn't mean it was not radially buckled and it is still a cycle wheel. |
#24
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Tied and soldered spokes.
On 23 Nov, 22:40, Naqerj wrote:
thirty-six wrote: On 22 Nov, 18:08, Ian Smith wrote: Likewise, I think you'll always get a lateral buckle from a wheel before you get a radial buckle. If always, then wheels have too poor a lateral stability. The other way round: it that the radial stability than is greater than strictly necessary, rather than lateral stability being poor. I dont comprehend this. ^ *Even lateral stability is greater than necessary - a bicycle wheel works perfectly well in a tricycle, which subjects it to more lateral force than a bicycle does. A tricycle wheel usually has cantilever axles which are thicker and flange offset is greater on the dual track axle. A bicycle wheel can only be used for the single track axle, if the machine is ridden hard. The high proportion of radial stability compared to lateral is pretty much determined by the shape of the space the wheel has to fit into. If the 3" flange spacing on 27/28" wheels was determined to be good a century ago and so standardized then, then it's good for today. Materials have changed. Specifically the choice of stainless spokes. These require specific attention if they are to match the performance of carbon steel spokes. |
#25
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Tied and soldered spokes.
"thirty-six" wrote in message
... Materials have changed. Specifically the choice of stainless spokes. These require specific attention if they are to match the performance of carbon steel spokes. Filing notches or applying strong acid? The weird thing is despite the peculiarities of your build process, your wheels probably turn out ok, because you probably do put enough tension in them rather than the low value you claim to. Come to Settle and I'll measure your spoke tension. The riding here is good - lots of steep hills to practice descending on. |
#26
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Tied and soldered spokes.
On 24 Nov, 03:19, "Clive George" wrote:
"thirty-six" wrote in message ... Materials have changed. *Specifically the choice of stainless spokes. These require specific attention if they are to match the performance of carbon steel spokes. Filing notches or applying strong acid? The weird thing is despite the peculiarities of your build process, your wheels probably turn out ok, because you probably do put enough tension in them rather than the low value you claim to. Come to Settle and I'll measure your spoke tension. The riding here is good - lots of steep hills to practice descending on. i'VE ASSESSED tension using musical pitch and it equated to 170lbf for a 36 spoke heavy duty sprint wheel usin g 15swg carbon steel spokes. But I dont build to a tension. I build to a desired wheel response. Stop being obsessed about spoke tension, it is wheel response which is important, not some number on a hoogywotsit. There is an ideal spoke tension which is best determined through testing of the completed wheel. I use a cobbled road if I am unsure after using static load testing. |
#27
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Tied and soldered spokes.
thirty-six wrote:
i'VE ASSESSED tension using musical pitch and it equated to 170lbf for a 36 spoke heavy duty sprint wheel usin g 15swg carbon steel spokes. How do you get from pitch to lbf? It's got me baffled, you must have some amazing testing gear. -- Its never too late to reinvent the bicycle |
#28
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Tied and soldered spokes.
On 25 Nov, 10:41, Keitht KeithT wrote:
thirty-six wrote: i'VE ASSESSED *tension using musical pitch and it equated to 170lbf for a 36 spoke heavy duty sprint wheel usin g 15swg carbon steel spokes. * How do you get from pitch to lbf? It's got me baffled, you must have some amazing testing gear. -- Its never too late to reinvent the bicycle A micrometer to check the spoke gauge at 14swg (0.080DIA) a steel ruler to check spoke length (12") and a chromatic tuner with a clip on microphone to measure musical pitch. Of course I don't need to use any of these to build wheels to excellent standards. It is though, nice to check the wheel, following a few good whacks, with the tuner to see that its stability has remained. Very slight variences are sometimes observed but have not been more than 15% of a semitone and dont get any worse if left. It is necessary in this instance to accurately balance pitch in the first place using the tuner so as to provide a reference pitch. |
#29
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Tied and soldered spokes.
On Wed, 25 Nov 2009 10:41:27 -0000, Keitht KeithT wrote:
thirty-six wrote: i'VE ASSESSED tension using musical pitch and it equated to 170lbf for a 36 spoke heavy duty sprint wheel usin g 15swg carbon steel spokes. How do you get from pitch to lbf? It's got me baffled, you must have some amazing testing gear. I know you probably weren't expecting a serious answer, but there is one: http://hyperphysics.phy-astr.gsu.edu...es/string.html Should work pretty well if you use guitar strings (preferably unwound) in place of spokes. How well it works for double butted I wouldn't like to guess, but it should get you in the right ball park. -- Rob |
#30
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Tied and soldered spokes.
On 25 Nov, 12:51, thirty-six wrote:
On 25 Nov, 10:41, Keitht KeithT wrote: thirty-six wrote: i'VE ASSESSED *tension using musical pitch and it equated to 170lbf for a 36 spoke heavy duty sprint wheel usin g 15swg carbon steel spokes. * How do you get from pitch to lbf? It's got me baffled, you must have some amazing testing gear. -- Its never too late to reinvent the bicycle A micrometer to check the spoke gauge at 14swg (0.080DIA) a steel ruler to check spoke length (12") and a chromatic *tuner with a clip on microphone to measure musical pitch. *Of course I don't need to use any of these to build wheels to excellent standards. *It is though, nice to check the wheel, following a few good whacks, with the tuner to see that its stability has remained. *Very slight variences are sometimes observed but have not been more than 15% of a semitone and dont get any worse if left. *It is necessary in this instance to accurately balance pitch in the first place using the tuner so as to provide a reference pitch. Forgot to answer your put question. I used a table to give the frequency of the musical pitch notation indicated on my £5 Lidl tuner. I then used an algerbraic formula to determine the tension in the wire based on its weight, length and frequency IIRC. The actual tension of the spoke makes no difference to me because I work well within the safe stresses of the materials in hand. If I was to build up wheels will stupid light rims, as well as using steel washers, I would make some calculations on wether the resulting spoke tension could be continually carried by the rim. I have been happy to build 28 spoke and up wheels without recourse to measuring spoke tension or calculation. A lightweight 24 spoke is pushing it for me because I dont have the experience with these rare rims. |
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