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#51
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Physics for marketing professionals
On 3/30/2015 2:22 PM, James wrote:
On 31/03/15 01:32, jbeattie wrote: On Sunday, March 29, 2015 at 8:20:25 PM UTC-7, James wrote: On 30/03/15 11:08, John B. Slocomb wrote: But Brandt, in "The Bicycle Wheel", recommended spoke tension to be just a tiny bit below "Taco Tension" which would seem to imply that loss of a spoke or two would cause the wheel to distort severely and thus be unrideable. So a broken Kevlar lacing would be only slightly less robust. That book was written at a time that normal rims for Jobst were about 20mm wide and 10mm deep (for tubulars). The rims were not very strong by themselves. If you try to taco an aero aluminium or CF rim today, you will more likely rip the spoke through the rim before it tacos, or break spokes, or the hub. A better description of good spoke tension is something like 1/3 of the yield strength of a spoke. His favorite rim was the Mod E2/MA2, which was a pretty robust 450g rim. You could do the soft-taco thing and the rim would recover, and with the double eyelets, you didn't get rim cracking -- usually. I had some MA2s where the sockets came right through the rim wall. Those tensions were also hard on hub flanges and unworkable for modern, 130mm high-dish, low weight, lower spoke count clinchers. IMO, a better description of spoke tension is the rim manufacturers' recommended tension along with some mild thread-lock like Teflon paste or linseed oil. I have the first edition of the book and don't know if later editions changed the basic formula for determining spoke tension, but I always thought that was one part of the book that needed revision. Perhaps my use of the word "strong" did not convey quite what I meant. I should have written "The rims (Mod E2/MA2) were not very stiff by themselves." I still don't believe the MA2 rim is "robust" though, by today's standards. Modern deep aero rims are far stronger and stiffer. This is obvious because they don't need 32 or more spokes to build a reliable wheel. All that and made of much better material now as well. -- Andrew Muzi www.yellowjersey.org/ Open every day since 1 April, 1971 |
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#52
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Physics for marketing professionals
On Monday, March 30, 2015 at 12:24:05 PM UTC-7, AMuzi wrote:
On 3/30/2015 2:22 PM, James wrote: On 31/03/15 01:32, jbeattie wrote: On Sunday, March 29, 2015 at 8:20:25 PM UTC-7, James wrote: On 30/03/15 11:08, John B. Slocomb wrote: But Brandt, in "The Bicycle Wheel", recommended spoke tension to be just a tiny bit below "Taco Tension" which would seem to imply that loss of a spoke or two would cause the wheel to distort severely and thus be unrideable. So a broken Kevlar lacing would be only slightly less robust. That book was written at a time that normal rims for Jobst were about 20mm wide and 10mm deep (for tubulars). The rims were not very strong by themselves. If you try to taco an aero aluminium or CF rim today, you will more likely rip the spoke through the rim before it tacos, or break spokes, or the hub. A better description of good spoke tension is something like 1/3 of the yield strength of a spoke. His favorite rim was the Mod E2/MA2, which was a pretty robust 450g rim. You could do the soft-taco thing and the rim would recover, and with the double eyelets, you didn't get rim cracking -- usually. I had some MA2s where the sockets came right through the rim wall. Those tensions were also hard on hub flanges and unworkable for modern, 130mm high-dish, low weight, lower spoke count clinchers. IMO, a better description of spoke tension is the rim manufacturers' recommended tension along with some mild thread-lock like Teflon paste or linseed oil. I have the first edition of the book and don't know if later editions changed the basic formula for determining spoke tension, but I always thought that was one part of the book that needed revision. Perhaps my use of the word "strong" did not convey quite what I meant. I should have written "The rims (Mod E2/MA2) were not very stiff by themselves." I still don't believe the MA2 rim is "robust" though, by today's standards. Modern deep aero rims are far stronger and stiffer. This is obvious because they don't need 32 or more spokes to build a reliable wheel. All that and made of much better material now as well. But, alas, the new rims are more prone to spoke hole cracking. The spoke sockets on the E2/MA2 were nice. I cracked a few Aeorheads in the transition from old-style wheel building to new (i.e. building with a tensiometer and a manufacturer's spec tension instead of near-taco tension). I've never built a pair of deep aero rims, so I don't know how those behave.. -- Jay Beattie. |
#53
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Physics for marketing professionals
the street level Tiwan/Japanese 10 speed/27" rims were forgiving in trueing up, trueing after bending. malleable 'junk'. World Class not Euro Class. Washers were in vogue.
replaced by the double wall at that extreme. |
#54
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Physics for marketing professionals
On Mon, 30 Mar 2015 08:32:28 -0700 (PDT), jbeattie
wrote: His favorite rim was the Mod E2/MA2, which was a pretty robust 450g rim. You could do the soft-taco thing and the rim would recover, and with the double eyelets, you didn't get rim cracking -- usually. I had some MA2s where the sockets came right through the rim wall. Those tensions were also hard on hub flanges and unworkable for modern, 130mm high-dish, low weight, lower spoke count clinchers. IMO, a better description of spoke tension is the rim manufacturers' recommended tension along with some mild thread-lock like Teflon paste or linseed oil. I have the first edition of the book and don't know if later editions changed the basic formula for determining spoke tension, but I always thought that was one part of the book that needed revision. It was written for learning to build wheels without a tensiometer, since those were rare at the time. The "soft taco" method, while lacking precision, at least worked. Times have changed with weird rim designs, alternative spokes, etc. Well, if you're keeping up with things- I'm still riding MA2s and Sun CR 18s and have downtube shifters on the two bikes I ride the most (friction, no less, but I am up to 8 speed on one and have 9 sp STI on the tandem... I dislike STI, but there are no downtube shifter bosses to upgrade to DT shifters). |
#55
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Physics for marketing professionals
On Sun, 29 Mar 2015 23:54:33 -0400, Frank Krygowski
wrote: On 3/29/2015 10:34 PM, Jeff Liebermann wrote: On Sun, 29 Mar 2015 12:29:25 -0400, Frank Krygowski wrote: Does non-twisting rope exist? Climbing rope. https://www.google.com/search?q=climbing+rope&tbm=isch Kernmantle construction. Braided (kern) nylon core. Woven outer sheath (mantle) for protection. As in https://www.google.com/search?q=clim...i h=606&dpr=1 ? Pretty pricey for hanging a kayak. I was hoping for, oh, under $10. The old cotton woven "cloths line" rope if they still sell it. http://www.homedepot.com/p/Unbranded...4097/202048188 $6.50 for a hundred feet. -- Cheers, John B. |
#56
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Physics for marketing professionals
Hooray! Now I can upgrade to low spoke count boutique wheels, and ditch the 36-spoke hand built wheels I've been riding for a couple decades, without a problem.
Best, Larry |
#57
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Physics for marketing professionals
On Wednesday, April 1, 2015 at 6:52:36 AM UTC-4, LF wrote:
Hooray! Now I can upgrade to low spoke count boutique wheels, and ditch the 36-spoke hand built wheels I've been riding for a couple decades, without a problem. Best, Larry Dear Larry...look thru http://goo.gl/1zK1Y4 |
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