Originally Posted by
knowledgdropper
The point I was trying to make was that people don't "measure" spin-up with the wheel in the air and their hand spinning the crank. You say that the idea of spin-up is bogus and that you believe this to be true on the strength of your prescribed test.
I'm saying that your test is invalid to quantify spin-up because your test essentially only looks at rotational mass- when there are lots of other variables to consider. If spinning a wheel on a stand means "spin-up" to you, then OK, you're right, there's almost no perceptible difference between any bicycle wheel. However- "I do not think it means what you think it means."
I don't believe that easy spin-up should automatically be equated with sheer lightness- which is what a lot of people seem to do when trying out new wheels. I think of spin-up as a function of actual riding, with real loads and forces acting on the wheel. As such, I see the concept of spin-up as being more related to the stiffness of a wheel- and this appears to be where you and I differ.
It might be different in drag racing, but most of the time people here talk about how easy wheels are to spin up because they're light. Do a search, or even look at the posts in this thread, or at a Bicycling magazine "review."
But, yes we agree on the physics at least. I still think stiffness of a wheel are way overrated, but you're right in that an unweighted spin-up doesn't tell you anything about that.