re: 60 MPH...achieveable? Who cares?!? Let blueprint an engine!
I have to admit that while I don't worry about doing a ton on my Goldwing or even on my Silverwing scooter (yes it will, easily) I get a wee bit nervous on my motorbike at 35mph. I rode 40mph downhill on a pedal bike once which didn't bother me but doing that on my motorbike would give me the willies. I think it's because of the engine chain locking up the rear wheel and dumping me when I first rode the thing. 20-25mph suits me fine on it.
Goldwing 1500, Silverwing 600, Schwinn 49