#11
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butted spokes (?)
Phil, Squid-in-Training wrote:
methods. some are indeed swaged, but some others are drawn and yet others are ground & polished. Does Wheelsmith do the last one? I've noticed that... yup. |
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#12
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butted spokes (?)
Use 14/15/14 gauge spokes(2mm/1.8mm/2mm), and lace them inside pulling for a disc wheel. Could you explain what does it mean exactly? Any scheme etc.? |
#13
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butted spokes (?)
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#14
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butted spokes (?)
jim beam wrote: 3) what spokes would you reccomend (thickness) and why ? 2mm/1.8mm/2mm. best trade-off between fatigue strength and stiffness. stiffness is important for lateral stability. Rinard found that lateral stiffness of a wheel changed much less than the difference in spoke stiffness (look for #7 at the bottom): http://www.sheldonbrown.com/rinard/wheel/ A 90% increase in spoke siffness (1.45mm dia to 2mm dia) produced only an 11% increase in lateral wheel stiffness. |
#15
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butted spokes (?)
jim beam wrote: go to sapim.be and dig about for their fatigue strength tables. http://www.sapim.be/index.php?st=pro...=fatiguetes t 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... |
#16
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butted spokes (?)
Ron Ruff wrote:
jim beam wrote: go to sapim.be and dig about for their fatigue strength tables. http://www.sapim.be/index.php?st=pro...=fatiguetes t 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. |
#17
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butted spokes (?)
Ron Ruff wrote:
jim beam wrote: 3) what spokes would you reccomend (thickness) and why ? 2mm/1.8mm/2mm. best trade-off between fatigue strength and stiffness. stiffness is important for lateral stability. Rinard found that lateral stiffness of a wheel changed much less than the difference in spoke stiffness (look for #7 at the bottom): http://www.sheldonbrown.com/rinard/wheel/ A 90% increase in spoke siffness (1.45mm dia to 2mm dia) produced only an 11% increase in lateral wheel stiffness. sure, so why don't you include damon's comment about the rim contributing to wheel stiffness as well? |
#18
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butted spokes (?)
jim beam wrote: sure, so why don't you include damon's comment about the rim contributing to wheel stiffness as well? I thought that was obvious... at any rate it was the same rim in both tests... and I suspect that on an MTB wheel the rim stiffness would contribute even more, making the effect of spoke stiffness even less. |
#19
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butted spokes (?)
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? |
#20
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butted spokes (?)
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. yup. Still, it seems odd that they would have presented it as "wheel revolutions" when it really isn't... a translation thing? and it makes their spokes look bad. don't think so. as a relative measure between sapim's different spokes, it's tells you what you need to know. as an absolute measure between brands, i think it interesting that none of the other manufacturers have the minerals to publish any fatigue info at all! Also, that 200lb cycle is roughly only 20% of the tensile strength that they list elsewhere... a huge difference between fatigue and static strength. sure, there's a spoke elbow on the bottom of this spoke bending back & forth on each stress cycle. that'll raise the stress in the skin of the bend considerably. you'll never see that reflected in static loading. Do you know of any other (hopefully better) online data regarding spoke fatique and strength? carl fogel posted a pdf by someone named prof. gavin a while back. istr that it contained fatigue testing. other than that, your googling is as good as mine. |
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