butted spokes (?)

On 4-Sep-2005, jim beam wrote:

that is /so/ wrong. the head is upset. but that's not butting.

Sock Puppet is upset over the constant head butting between jim beam and
Jobst Brandt.

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wrote:
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.

Thanks once again Carl!

If Sapim used a 90kgf load cycle, and they are getting 1,000,000 cycles
or better, then their "data" (marketing hype?) looks pretty good
compared to the '84 Stanford test of Wheelsmith spokes. That is 883N
which is a stress of 348N/mm^2 on a 1.8mm spoke. According to Fig 13,
for Wheelsmith spokes the cycles to fatigue are about 200,000.
1,000,000 cycles is about 210N/mm^2 (533N); 10,000,000 cycles is about
105N/mm^2 (267N).

From Gavin's testing the "smooth road" cycle of stress was about
70N/mm^2 per wheel revolution, while the extreme (pothole) stress was
150N/mm^2... so we are looking an estimated fatigue life in excess of
10,000,000 cycles (13,400 miles)... maybe a lot more.

Did Stanford test any butted spokes?

Getting back to the OP's original question, it is interesting that
Sapim rates their CX-ray spokes as being the strongest (cycles of
fatigue @ 90kgf) ones they sell... by far. And these are equivalent to
only 1.5mm dia in the middle section! The static strength is 1600N/mm^2
which corresponds to a load of 2,832N, while the Race with 1.8mm middle
section has a static strength of 1350N/mm^2 or 3,430N... making it 21%
stronger in static loading. So I guess the heavier spoke could be
stronger for extreme and unusual loads, but for high cycles of loading
the lighter spoke should hold up longer.