Re: How Fast are You going? - I wana know
T-Lo, a smaller sprocket on the rear wheel (which will have fewer teeth) makes the wheel spin faster as each foot of chain is pulled over it. I've seen sprockets ranging from around 30 teeth up to maybe 48 teeth advertised on E-bay, though I'm sure there are some available outside that range. I just search for "bicycle engine sprocket" and up come many choices.
Rustycase and 2door, I too am in the Denver area and have the added challenge of nearly 6,000 ft elevation to work around. (That may be a big factor which limits my top speed to around 23 mph.) I tend to be a believer in the philosophy of the "20 mph club", and generally keep my speed at or below 20mph. (Easier on the engine, less painful on my body should I have some sort of "incident" while riding.)