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The Basics of Wheel Alignment and Wheelbuilding
You'll find a reasonable tutorial on the basics of wheel alignment and
wheelbuilding at www.bikewebsite.com Have fun! - Jeff - |
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The Basics of Wheel Alignment and Wheelbuilding
You'll find a reasonable tutorial on the basics of wheel alignment and wheelbuilding at www.bikewebsite.com Have fun! - Jeff - Nothing at all about stress relieving. Pressing on the rim, against the axle end, will untwist spokes but it is difficult to press hard enough to relieve internal stresses in individual spokes that way. Better to add a step: wearing heavy gloves, grasp pairs of spokes and squeeze hard, repeating all around the wheel. Done properly, this will practically eliminate the need for later truing and the spokes will last a long, long, time. |
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The Basics of Wheel Alignment and Wheelbuilding
On Fri, 30 Jul 2004 17:13:50 GMT, Ted
wrote: You'll find a reasonable tutorial on the basics of wheel alignment and wheelbuilding at www.bikewebsite.com Have fun! - Jeff - Nothing at all about stress relieving. Pressing on the rim, against the axle end, will untwist spokes but it is difficult to press hard enough to relieve internal stresses in individual spokes that way. Better to add a step: wearing heavy gloves, grasp pairs of spokes and squeeze hard, repeating all around the wheel. Done properly, this will practically eliminate the need for later truing and the spokes will last a long, long, time. Dear Ted, Outside of posts on rec.bicycles.tech and references to Jobst's book, do you know of any studies, tests, or web pages that address what we're calling "stress relieving" and "stress relief"? The quotation marks are used only to broaden the question, since there may be other names and methods for spoke-squeezing, as well as other claims for the process is supposed to do to the spokes. Sheldon Brown, for example, quotes Jobst, but gives the spokes a twist with a smooth crank arm instead of squeezing them: http://www.sheldonbrown.com/wheelbuild.html#seating It would be interesting to find out if Japanese Keirin bicycle mechanics squeeze or twist spokes. Maybe John Dacey knows? Carl Fogel |
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The Basics of Wheel Alignment and Wheelbuilding
On Sat, 31 Jul 2004 07:06:06 +1000, daveornee
wrote: Wrote: On Fri, 30 Jul 2004 17:13:50 GMT, Ted wrote: You'll find a reasonable tutorial on the basics of wheel alignment and wheelbuilding at www.bikewebsite.com Have fun! - Jeff - Nothing at all about stress relieving. Pressing on the rim, against the axle end, will untwist spokes but it is difficult to press hard enough to relieve internal stresses in individual spokes that way. Better to add a step: wearing heavy gloves, grasp pairs of spokes and squeeze hard, repeating all around the wheel. Done properly, this will practically eliminate the need for later truing and the spokes will last a long, long, time. Dear Ted, Outside of posts on rec.bicycles.tech and references to Jobst's book, do you know of any studies, tests, or web pages that address what we're calling "stress relieving" and "stress relief"? The quotation marks are used only to broaden the question, since there may be other names and methods for spoke-squeezing, as well as other claims for the process is supposed to do to the spokes. Sheldon Brown, for example, quotes Jobst, but gives the spokes a twist with a smooth crank arm instead of squeezing them: http://www.sheldonbrown.com/wheelbuild.html#seating It would be interesting to find out if Japanese Keirin bicycle mechanics squeeze or twist spokes. Maybe John Dacey knows? Carl Fogel http://yarchive.net/bike/stress_relieve.html Might be worth a look. Dear Dave, Yes, that's a typical 1998 rec.bicycles.tech thread with the usual suspects. It's one of the exchanges that led me to wonder about the matter. Here's a fair example: That is why I asked for references to hard scientific papers, a mathematical explanation or other such research. The book gives both an explanation and experimental methods by which you can convince yourself of these effects. Had someone written about it previously, I would not have written "the Bicycle Wheel". Much of what the book contains could previously not be found in any literature. The work of Karl Wiedemer is cited. Your book contained no mathematics on this topic, no results of proper controlled experiments on the cause of the effects and no references that I could look up. In particular, I was extremely surprised that it didn't seem to contain any references to where you had published your analyses and experiments in the scientific literature. Well! I guess that means it is all wrong as you state. Yes, I have tried doing a literature search, but found nothing. As you see, I found more than you. With help I located Karl Wiedemer's publication on the subject. Prof. Wiedemer, now retired, did his analysis at the same time I did and he also had no references because it was new work in a field that had progressed without analysis for a long time. Prof. Pippard in England wrote extensively on the subject but never discovered the mode of wheel loading and deflections that I and Wiedemer presented. As I said, I made the analysis by measurement and was rejected by professors of engineering. When I presented the finite element analysis, these same people chose to change the subject and get back to "serious" work. [ and so on] Googling for "karl wiedemer" produces four other pages, all in German, one on safety devices for coal dust, one on blast furnace slag, one on the history of some club from 1896, and two other in pdf format that Google does not offer to translate. Spoke-squeezing is an intriguingly mysterious subject to research. I remain agnostic, wavering one way and the other, but haven't seen any experimental data or analyses involving bicycle spokes. If you have the 3rd edition, perhaps you could peek at the Wiedemer stuff and give me your thoughts on it? Carl Fogel |
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The Basics of Wheel Alignment and Wheelbuilding
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The Basics of Wheel Alignment and Wheelbuilding
On Fri, 30 Jul 2004 19:44:49 -0700, jim beam
wrote: wrote: snip Spoke-squeezing is an intriguingly mysterious subject to research. I remain agnostic, wavering one way and the other, but haven't seen any experimental data or analyses involving bicycle spokes. If you have the 3rd edition, perhaps you could peek at the Wiedemer stuff and give me your thoughts on it? you may also want to consider this question: q: elevator safety certification requires loading the cab to double it's "safe working load". this is to test the wire ropes that suspend it. the reason is that fracture mechanics predict that this process will typically reveal by failure any latent flaws. but, if we extend spoke squeezing theory, wouldn't this overload procedure also prevent fatigue of elevator cables? a: no. elevator cables still fatigue and need regular testing, inspection & replacement. the bottom line is that there is no quantification or testing of this spoke squeeze theory. squeezing "as hard as you can" is no more scientific than building with spoke tension "as high as the rim can bear". i would suggest to you that the reason academics "change the subject and get back to "serious" work" is because this theory is mere speculation - it's author has shown no basis in statistical fact, and most definitely not by metallurgical analysis. Dear Jim, Aaaargh! I really wish that you could have thought of a different example, since I didn't want to hear that elevator cables need replacing. I draw comfort from a vague memory that they have some kind of safety brake, according to Ambrose Bierce and to some famous demonstration in which Otis cut the cable while standing on top of an elevator. Two questions occur to me, both illustrating the depths of my ignorance. First, how much do elevator cables resemble spokes? Are they made of stainless steel? Does it matter that they bend around pulleys in a constant side-to-side flexing different than spokes? Do spokes and cables go through similar cycles of tension, partial release, and back to normal tension? Second, do spokes in well-built (by whatever means) wheels require constant inspection and replacement? I understand that spokes are different from cables. I'm just wondering how big the differences are and how much they matter. See you in the stairwell, Carl Fogel |
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The Basics of Wheel Alignment and Wheelbuilding
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The Basics of Wheel Alignment and Wheelbuilding
jim beam writes:
wrote: snip Spoke-squeezing is an intriguingly mysterious subject to research. I remain agnostic, wavering one way and the other, but haven't seen any experimental data or analyses involving bicycle spokes. If you have the 3rd edition, perhaps you could peek at the Wiedemer stuff and give me your thoughts on it? you may also want to consider this question: q: elevator safety certification requires loading the cab to double it's "safe working load". this is to test the wire ropes that suspend it. the reason is that fracture mechanics predict that this process will typically reveal by failure any latent flaws. but, if we extend spoke squeezing theory, wouldn't this overload procedure also prevent fatigue of elevator cables? a: no. elevator cables still fatigue and need regular testing, inspection & replacement. Of course they fatique. They are constantly being wound around a drum and unwound with a large weight dangling on the end. This doesn't happen with spokes. Spokes are one fairly thick wire under a fairly small load, elevator cables are thin-stranded cables with internal friction, corrosion challenges, etc. Additionally, a spoke supports a load much differently than an elevator cable, as has been discussed and verified- independently of Brandt, BTW- by finite element analysis. I see you're keeping the fine art of red herrings alive. the bottom line is that there is no quantification or testing of this spoke squeeze theory. squeezing "as hard as you can" is no more scientific than building with spoke tension "as high as the rim can bear". i would suggest to you that the reason academics "change the subject and get back to "serious" work" is because this theory is mere speculation - it's author has shown no basis in statistical fact, and most definitely not by metallurgical analysis. And it's easy to take cheap shots when he's out of town and not able, therefore, to respond. I don't quite know why it sticks in your craw so much to admit even the possibility that Jobst is right, and it's an interesting psychological problem especially when combined with your anonymity behind a boozy screen name. But if you're going to seriously critique his work and not just take potshots, come up with a quantified and testable alternative analysis. Prove him wrong. Put up or shut up. Frankly, jim beam old buddy old pal, I don't think you have the stuff. |
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The Basics of Wheel Alignment and Wheelbuilding
jim beam writes:
wrote: Second, do spokes in well-built (by whatever means) wheels require constant inspection and replacement? if you read the instructions that come with all these expensive pre-built wheels yes! but, that's only a cursory visual inspection. it's just like the contrasts between the safety & inspection regimes for cars vs planes, wheel spokes are not usually considered a high fatality risk, so there's no reason to subject them to a rigorous expensive certification procedure. A nice duck and weave instead of answering the question. You sound like a politician, and I've had enough of that for one week. The answer to Carl's question is "no." I ride my bikes, I never bother to inspect the spokes and I haven't broken a spoke in 50,000 to 60,000 miles of riding, racing, light touring and cyclo-cross. Of course I built those wheels using a method of wheelbuilding that mr. beam is attempting to discredit by misleading analogies and such; I suppose you have to resort to that sort of thing when you can't produce facts that are contradictory. The last spoke I broke was in about 1994 on a group training ride; rather embarassing for the guy who built the wheel, as he was along for the ride. It was an Asahi 14g spoke, on the non-drive side of a 7 sp wheel spaced at 126 mm; Sun rim, Avocet Model III hub (Campy copy). Hmm, correction, the last spokes I broke were in an 18" wheel built on an SRAM 3x7 hub in a folding bike (Birdy, which was infamous for broken spokes for a couple of years). I rebuilt the wheel in 1999 or 2000 and no broken spokes since, but that bike doesn't see many miles. |
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