Originally Posted by
dabac
The theory is clear that the NDS spokes should have it worse.
This a theory that I’ve seldom seen in practice. I’ve broken lots of spokes myself and I see dozens per year at my local co-op. I would estimate the number of my broken spokes and the ones at the co-op on the nondrive side to be around 10%. The vast majority occur on the drive side. My hypothesis on how this happens is that the amount of load/unloading of the spoke puts more stress on the driveside spoke because the magnitude of the difference is larger on the driveside. Tension is higher on the driveside so the decease in tension is greater on the driveside than the nondriveside.
I’ve sometimes wondered if it’s possible to build a wheel with low enough tension so that the NDS spokes survive b/c of never seeing enough tension to fatigue, while putting the DS spokes right in the fatigue range.
And there’s always the option of the really sloppy build where some spokes simply started out a lot slacker.
Your solution would only result in more broken spokes.
Last IGH I built up had an 8% difference in spoke tension between DS and NDS. Last derailer gear wheel I built had about 60% NDS spoke tension.
As someone already wrote, what breaks spokes is constant bending, the frequent (big) changes in tension that causes metal fatigue. It’s far easier to get all spokes into the ”safe” zone on an IGH or otherwise near symmetrical wheel. For a comparable build quality, no mystery there.
IGH and single speed wheels seldom break spokes like front wheels for the same reason...the tension is nearly equal on both sides. The way to make a rear wheel with much more even tension is to use a off-center rim (OCR). The rim is built with an offset in the spoke bed to the nondrive side. This decreases the tension differences between the two sides from about 80% to about 60%. It’s not like a front wheel but is usually enough to make the wheels stronger.
Additionally, we should build wheels with stronger
spokes. Rims get all the glory when it comes to strength but the “glory” is misplaced. The strongest rim around still undergoes the same flattening when the rim reaches the bottom of the wheel and the spoke undergo the same detensioning/retensioning cycle. A thicker head at the elbow withstands fatigue better than thinner heads. If nothing else, a 2.3mm spoke moves less in the hub which also reduces fatigue. Eric Hjertberg t
has a really good article that explains my point quite well.