1. It's 4-5 % frictional power loss would be the lowest of any geared uni. Perhaps making it the fastest.
I don't think frictional power loss is going to be your speed limiting factor for making the fastest uni. What you need is a stable unicycle with a lightweight wheel and a big enough gear to maintain the optimal cadence for the particular rider.
There are already unicycles like the 36" Schlumpfs which have a much bigger gear than people can push efficiently (or are happy to push)- evident in the fact that these machines tend to be fitted with longer cranks than the equivalent fixed Coker. ie- you're not gearing up a unicycle much if you end up having to use longer cranks on it because it becomes too hard to push (unless you're more efficient at lower cadences). The one's I've seen have all been fitted with 170/175mm cranks. I doubt very much that a geared Coker would go very fast on the flat with 100mm cranks unless the wheel was lightened significantly. The geared 29"/110mm should be about right. I reckon that would be the fastest 'on-the-flat' Uni currently.
I want to talk winning by design here. Let's pretend for a moment that the rider is generic. Mr. , Ms. , one horsepower. Different gearing setup's may reach the optimum mechanical advantage that we need to reach top speed with one horsepower. The design that has the lowest % of power loss in the drivetrain will set top speed, because it will deliver the greatest % of one horsepower to the wheel.
