#21
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butted spokes (?)
Southern Comfort writes:
jobst calls them all "swaged" but that's because he's seemingly unaware of the fact that different spokes are made by different methods. some are indeed swaged, but some others are drawn and yet others are ground & polished. the generic term for /all/ reduced diameter spokes is therefore "butted". don't let anyone who knows nothing about these different production methods tell you otherwise. "Butted" comes from the upsetting of the end of a rod to make a thicker feature such as a spoke head or to thicken the end on which threads are to be cut. However, spokes are not thickened but thinned by swaging, a metal forming process that can be done by hammering on an anvil as was done in the days of yore, or by drawing through a split die clamped onto the spoke mid-section. DT chose to use the split die while hammering it in rotation around the spoke. This not only reduces the cross section but work hardens it. Just drawing the spoke through a split die (with helical seam) may be faster but usually leaves drawing marks that must be polished out. Toward the end of their days in business, Stella spokes had terrible draw marks on their swaged spokes. The process can be simulated by other means such as metal removal, something that does not make as strong a spoke as swaging. Jobst Brandt |
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#22
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Jasper Janssen writes:
Disc brake torque is no greater spoke load than peak pedaling torque and it is distributed to both sides of the wheel, which pedaling torque is not. Why is it distributed? Disc brake torque is applied in pretty much the same place on the wheel as torque through a freewheel, so wouldn't it be mostly on the brake-side spokes, like pedaling torque is on drive side? In both cases you essentially add torque at one hub flange. Hubs made for disc brakes generally have a large diameter spool between flanges. If they don't don't buy them. This is especially true for rear hubs. The good disc brake front hubs I have seen have such a spool, so braking spoke load is fairly equal on both sides of the wheel. Jobst Brandt |
#23
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#24
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butted spokes (?)
On 4 Sep 2005 18:04:24 -0700, "Ron Ruff"
wrote: jim beam wrote: Ron Ruff wrote: If I calculated correctly their "fatigue test" results seem a little odd. 1,000,000 wheel revolutions is only 1,340 miles (27*pi/12/5280*1,000,000). Even the CX-rays with 3,500,000 revolutions only get 4,690 miles. I would be nice to know more about that testing... all i've discovered is that it was done by cycling from 90kgf to zero. that's much higher than most wheels see in service. being as fatigue life is usually regarded as having a logarithmic relation to stress, you can see that your mileage will quickly increase with decreasing stress cycle. So, they stressed the spokes in an unusual way to get them to break sooner... fairly standard, I guess. Still, it seems odd that they would have presented it as "wheel revolutions" when it really isn't... and it makes their spokes look bad. Also, that 200lb cycle is roughly only 20% of the tensile strength that they list elsewhere... a huge difference between fatigue and static strength. Do you know of any other (hopefully better) online data regarding spoke fatique and strength? Dear Ron, If you haven't seen it, here's a paper on a variety of spoke details: http://www.duke.edu/~hpgavin/papers/...heel-Paper.pdf It mentions the Wheelsmith-Stanford testing of spokes to destruction from some years ago. Professor Gavin was kind enough to send me the details of the Wheelsmith tests, but while they were on their way, one of our more obnoxious anonymous nitwits became so unspeakable that I apologized to Professor Gavin for dragging him into our cesspool and promised not to even open the envelope when it arrived. [Carl stares longingly at an unopened manila envelope with a $3.85 02-22-2005 postmark. Feels like more than 30 pages, much too thick to read by holding the envelope up to the light. Probably full of really fascinating stuff. Cursed ethics! Back to the shelf. Maybe someone else will find a copy.] Carl Fogel |
#25
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#26
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#27
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Jasper Janssen writes:
Hubs made for disc brakes generally have a large diameter spool between flanges. So do non-disc mountain hubs, including rears. If they don't don't buy them. This is especially true for rear hubs. The good disc brake front hubs I have seen have such a spool, so braking spoke load is fairly equal on both sides of the wheel. A smaller or larger hubshell that transmits more or less load from one side to the other can only mitigate the effect, it can't actually make it go away, can it? Make what go away? There is no problem with that such torque loading when you consider that many rear wheels survive with little torque reaching the left side spokes due to slender hub spools. Oh, and a related but non argumentative question for you: In frame tubing, over-sized, thin walled tubing can be lighter, stiffer, and nearly as strong. How does that work for hubshells? Wouldn't the ones with thick hubshells -- particularly in high-end, lightweight ranges like XTR -- have bigger axle holes inside to conserve weight? What is/would be the effect on rotational stiffness of thin wall, oversize hubshell tubing? Torsion load increase as the fourth power of diameter so you must compute the polar moment of inertia of the OD of the cross section of interest and subtract that of the ID. So you see it depends on both diameter and wall thickness. This stuff is in "the Bicycle Wheel". Jobst Brandt |
#28
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butted spokes (?)
Southern Comfort wrote:
jobst calls them all "swaged" but that's because he's seemingly unaware of the fact that different spokes are made by different methods. some are indeed swaged, but some others are drawn and yet others are ground & polished. the generic term for /all/ reduced diameter spokes is therefore "butted". don't let anyone who knows nothing about these different production methods tell you otherwise. Jobst Brandt replied: "Butted" comes from the upsetting of the end of a rod to make a thicker feature such as a spoke head or to thicken the end on which threads are to be cut. No, "butted" is a term descriptive of the _shape_, not the process. When something is thicker on the ends it is "butted." We've been over this before, and I gave an O.E.D. reference to this in a previous posting, but I don't feel like dragging my O.E.D. and the magnifying glasss again. Butted tubing is not made by thickening the walls at the ends of the tubes either, but by thinning the walls in the middle. The butt of a rifle is also not made by thickening, but rather by removing wood. I generally prefer not to use the term "swaged" to describe spokes, because all spokes are swaged...that's how the head is made. Jobst prefers the term "upset" for this operation, which is also correct. Sheldon "But.." Brown Newtonville, Massachusetts +-----------------------------------------+ | Man invented language to satisfy his | | deep need to complain. -- Lily Tomlin | +-----------------------------------------+ Harris Cyclery, West Newton, Massachusetts Phone 617-244-9772 FAX 617-244-1041 http://harriscyclery.com Hard-to-find parts shipped Worldwide http://captainbike.com http://sheldonbrown.com |
#29
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On Sun, 04 Sep 2005 23:27:24 -0400, Sheldon Brown
wrote: Southern Comfort wrote: jobst calls them all "swaged" but that's because he's seemingly unaware of the fact that different spokes are made by different methods. some are indeed swaged, but some others are drawn and yet others are ground & polished. the generic term for /all/ reduced diameter spokes is therefore "butted". don't let anyone who knows nothing about these different production methods tell you otherwise. Jobst Brandt replied: "Butted" comes from the upsetting of the end of a rod to make a thicker feature such as a spoke head or to thicken the end on which threads are to be cut. No, "butted" is a term descriptive of the _shape_, not the process. When something is thicker on the ends it is "butted." We've been over this before, and I gave an O.E.D. reference to this in a previous posting, but I don't feel like dragging my O.E.D. and the magnifying glasss again. Butted tubing is not made by thickening the walls at the ends of the tubes either, but by thinning the walls in the middle. The butt of a rifle is also not made by thickening, but rather by removing wood. I generally prefer not to use the term "swaged" to describe spokes, because all spokes are swaged...that's how the head is made. Jobst prefers the term "upset" for this operation, which is also correct. Sheldon "But.." Brown Newtonville, Massachusetts +-----------------------------------------+ | Man invented language to satisfy his | | deep need to complain. -- Lily Tomlin | +-----------------------------------------+ Harris Cyclery, West Newton, Massachusetts Phone 617-244-9772 FAX 617-244-1041 http://harriscyclery.com Hard-to-find parts shipped Worldwide http://captainbike.com http://sheldonbrown.com Dear Sheldon, It's always nice to meet someone else who dislikes that rectangular magnifier and the tiny print. And it's nice to see that you're not upset or making a S.W.A.G. about the butt of a joke. Carl Fogel |
#30
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On 4-Sep-2005, wrote: It's always nice to meet someone else who dislikes that rectangular magnifier and the tiny print. You can subscribe online for ONLY $295/year. http://www.oed.com/subscribe/individuals-amer.html -- Sock Puppet ----== Posted via Newsfeeds.Com - Unlimited-Uncensored-Secure Usenet News==---- http://www.newsfeeds.com The #1 Newsgroup Service in the World! 120,000+ Newsgroups ----= East and West-Coast Server Farms - Total Privacy via Encryption =---- |
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