Re: Choosing the right bike - Single Speed? Does it matter?
The gearing on the bike doesn't matter since the motor drives a seperate sprocket on the other side of the wheel. Gears are nice, however, for making it easy to pedal from a dead stop (you need to pedal a bit before kicking in the engine). You can buy a jackshaft kit which will allow you to use the motor with the bike's gears, but it costs an arm, a leg, and possibly a kidney.
Idk much about the quality of the RAW engines. I'll just say that it seems to really be a "luck of the draw" sort of thing with these Chinese motors. For this reason, a vendor with good customer support is great.