GeekAtLarge from Alexandria, VA on 10/16/2020 11:37:52 AM:
750 Watts is one horsepower. That is where the cutoff comes from. It is quite easy to purchase kits to equip bikes with 1500 Watt motors, and I assume that there are even larger motors available! (Think, Electric Motorcycles.) Most ebike purchases in the USA are at 750 watts or less. According to Bosch, who make ebike motors, The three classes are defined as follows:
Class 1: eBikes that are pedal-assist only, with no throttle, and have a maximum assisted speed of 20 mph.
Class 2: eBikes that also have a maximum speed of 20 mph, but are throttle-assisted.
Class 3: eBikes that are pedal-assist only, with no throttle, and a maximum assisted speed of 28 mph.
All classes limit the motor’s power to 1 horsepower (750W).