I was playing with my son at the park, and I noticed when he was on the merri-go-round and it was spinning, it would spin slower when he was at the edge of it, and faster when he would move to the middle. This made me think about wheel rotation. Since the hub is at the center of the wheel, it won't have as much effect on the rotation speed. The rim being at the edge, would be the component that you would want to be the lightest, right?

When I see the weight of a wheelset, this is the entire weight of the rim, spokes, hub, etc. Does the entire weight of the wheel matter that much? Shouldn't we be more concerned with just the weight of the rim and spokes, and not the hub itself, since the rim is the outermost part of the wheel (except the tire)?

Ok, weight weenies, what say you...

hoo boy! I can see a religious argument coming up!

To answer briefly: yes it matters, but not a whole bunch in the greater scheme of things.

M

Shouldn't we be more concerned with just the weight of the rim and spokes, and not the hub itself, since the rim is the outermost part of the wheel (except the tire)?
No.
http://www.biketechreview.com/archive/appa.pdf

yes it matters, but not a whole bunch in the greater scheme of things.

Well!!!! That was definitive!!! (just kidding!!)

And actually there probably will be a lengthy debate about this (again), but basically it comes down to a few grams. So if you ride Mavic OP's, you're really only going to be giving up maybe 20-30 grams either way (less than one oz I think). I'm assuming you're not spending money on AC or nimble wheels either. As far as I'm concerned, rotating weight only matters when accelerating (and decelerating). Therefore, accelerating will take (very very) slightly more watts with a heavier rim. Once you are up to speed, a heavier rim will maintain momentum better. Therefore, a heavier rim should allow you to same (very very very) few watts staying at constant speed.

In a few posts, you'll have a bunch of techie engineers quoting you mass * velocity * (&^^()*( formulas, but in general I think the above is correct.

No.
http://www.biketechreview.com/archive/appa.pdf

(see my earlier post)

No.
http://www.biketechreview.com/archive/appa.pdf

Uh...yeah...that makes it all clear. Thanks.

No.
http://www.biketechreview.com/archive/appa.pdf
If you have read article to which you refer, then you have to notice that answer is YES,
as inertial term has R² in denominator. So it does matter where weight is located.

So it does matter where weight is located.
That wasn't the question.

Shouldn't we be more concerned with just the weight of the rim and spokes, and not the hub itself, since the rim is the outermost part of the wheel (except the tire)?

I was playing with my son at the park, and I noticed when he was on the merri-go-round and it was spinning, it would spin slower when he was at the edge of it, and faster when he would move to the middle. This made me think about wheel rotation.

Your observation is correct, but it has little to do with bike wheels. You were observing conservation of (kinetic) energy - shifting the center of mass along the radius of a rotating object requires that the speed change in order to keep the kinetic energy constant (ignoring friction and wind drag losses). A bike wheel rotates at the same speed as the bike is moving forward. If you are worried about minimizing the energy required to accelerate the wheel, then cutting mass from the rim/tire is most effective. For two wheels of equal total weight, the one with the lighter rim/tire will accelerate with less energy required. However, it will also slow down more quickly (less flywheel effect) and the total energy differences are very small.

If, in a criterium for example, you are constantly accelerating and braking, then the distribution of weight in a wheel is meaningful. Likewise if you are in a "single acceleration" event, like one of those funky "bike against roller blader" events, the distribution of weight in a wheel is meaningful. Otherwise, energy is conserved and any extra effort required to spin up a heavier tire/rim is returned when coasting, as the bike doesn't slow down as fast. Again, the total energy differences are small.

Your observation is correct, but it has little to do with bike wheels. You were observing conservation of (kinetic) energy - shifting the center of mass along the radius of a rotating object requires that the speed change in order to keep the kinetic energy constant (ignoring friction and wind drag losses). A bike wheel rotates at the same speed as the bike is moving forward. If you are worried about minimizing the energy required to accelerate the wheel, then cutting mass from the rim/tire is most effective. For two wheels of equal total weight, the one with the lighter rim/tire will accelerate with less energy required. However, it will also slow down more quickly (less flywheel effect) and the total energy differences are very small.

If, in a criterium for example, you are constantly accelerating and braking, then the distribution of weight in a wheel is meaningful. Likewise if you are in a "single acceleration" event, like one of those funky "bike against roller blader" events, the distribution of weight in a wheel is meaningful. Otherwise, energy is conserved and any extra effort required to spin up a heavier tire/rim is returned when coasting, as the bike doesn't slow down as fast. Again, the total energy differences are small.

Kerry,
Thanks for the answer. That was exactly what I was looking for.