Originally Posted by erp
Both statements are correct - you can impart more spin on a disc with the same energy if you can grip closer to the center, which the wide rim achieves, and the added mass at the rim will tend to maintain more of the spin due to inertia (an object in motion stays in motion, yadda yadda yadda)
I don't think we need to go past thermodynamics to explain this, but I bet string theory would be pretty amusing to apply to this.
I'm gonna stick with Newton and thermodynamics and call it good.
Okay, so assuming that we have 100% efficient systems then it doesn't matter where you push on a bike wheel or on a disc. It will take the same amount of energy to give it the same amount of spin. The problem is humans aren't 100% efficient systems. You can get the bike tire going faster with the spokes because it's moving slower and you aren't using as much strength just getting your arm up to speed with the tire, let alone pushing it faster.
Having more weight near the edge of the disc means that you'll have more angular momentum given the same rpms on the disc. I wouldn't assume that you get the same amount of spin on those disc as others though, it will vary some. Anyway glossing over the details of why, you should be able to get more angular momentum on the disc which will act to help keep it on any given course longer.
There are several other effects though that are not taken into account by my previous statement though. And for today I'll leave it at that. I have to get back to work.
Oh and I don't know that we need to invoke Thermodynamics but we do need Bernoulli.