derbi senda and gilera smt for crossers, but ive heard there unrealible, same with rs, fast bikes but some can be fine some can be a bag of shit ive got a piaggio nrg (ped)and it does me fine 50mph on the flat plenty enough but obviosly if you want speed gears is the way to go. also dt 50's rare but good, and also theres a 50cc derbi manual, looks like a rs but is faster i think, forget its name.