hello, just browsing looking for ideas. i've had a few mini bikes and small motorcycles, and bunches of bikes but haven't tried a motor on a bike. anyway, one project i have i got a schwinn spoiler rear wheel with gears on one side and a disc brake on the other, so ther is no room for a left side sprocket. i'm wondering about the big ring/pulley on a whizzer. would the diameter be too big for a 20" wheel? bigger than the rim it's self i mean? is ther something similar but smaller diameter if so? thanks.