Amps can be thought of as the volume or quantity of electric power. To aid this analogy, the flow of amps is called the current, as in the flow of a river. Unlike a river, though, the speed of the current is fixed - only the volume varies. The maximum flow of amps in a bicycle drive system can vary from 10 to 60 or more. A current of 60 amps requires thick wiring and quite substantial switchgear.