It varies from state to state but usually the deciding factor is the motor. No motor? It's a bike, no matter how many wheels it has.
Amusingly enough many of the laws are old enough that they are written with "cc" mentioned, below 60cc is a "moped" above is a "motorcycle". Those rules will have to be updated to account for various traction devices.
Amusingly enough many of the laws are old enough that they are written with "cc" mentioned, below 60cc is a "moped" above is a "motorcycle". Those rules will have to be updated to account for various traction devices.