----- Original Message -----
From: "Mark Bulgier" <mark@bulgier.net>
>
> The claims are especially unrealistic with respect to stiffness, because
> even if the spoking pattern could double the stiffness (an absurd
suggestion
> no one is claiming), no one would notice. That's because all wheels are,
> for all practical purposes, infinitely stiff vertically already. Any
> vertical give they have is masked by the give in the tires, which is
> probably a hundred times greater. Vertical stiffness of wheels can be
> measured in the lab, but the differences are beyond the range of human
> perception.
While I agree that the twisted-spoke lacing does not offer a stiffness or durability advantage, I have to disagree about the "infinite stiffness" of wheels for practical purposes. I know what Jobst, etc claims, but I can't otherwise explain real world experience.
As we all generally accept, if I either drastically reduce my spoke count (say 32 to 16), or drastically decrease rim weight (say 400g GP-4 to a GEL-280, or less), wheel durability drops precipitously. While strength can still be in the useable range (big, strong track riders race on very low count, light-rimmed wheels), spoke fatigue life will suck. Either the lack of rim stiffness or the lack of spoke count stiffness must be replaced by the other to maintain a durable wheel.
I would love the opportunity to perform repeatable double-blind wheel tests, but I wholly believe that 12-spoke deep rim wheels ride harsher than 36-spoke shallow box rims, and that it's because they are more vertically stiff. Even though the tire does deflect many more times than any rim, it's amazing, even with low inflation pressures, how even the subtlest of pavement texture changes are perceivable.
There must be characteristics single-load lab tests and FEA models are missing. Maybe harmonic vibrations or something.
Jon Schaer
Columbus, OH