The two most common types of hub motors used in electric bicycles are brushed and brushless. Many configurations are available, varying in cost and complexity; direct-drive and geared motor units are both used. An electric power-assist system may be added to almost any pedal cycle using chain drive, belt drive, hub motors or friction drive. BLDC hub motors are a common modern design. The motor is built into the wheel hub itself, and the stator fixed solidly to the axle, and the magnets attached to and rotating with the wheel. The bicycle wheel hub is the motor. The power levels of motors used are influenced by available legal categories and are often, but not always limited to under 750 watts.
As of May 19, 2009, Nevada amended its state transportation laws to explicitly permit electric bicycles to use any "trail or pedestrian walkway" intended for use with bicycles and constructed with federal funding, and otherwise generally permits electric bicycles to be operated in cases where a regular bicycle could be. An electric bicycle is defined as a two- or three-wheeled vehicle with fully operable pedals with an electric motor producing up to 1 gross brake horsepower and up to 750 watts final output, and with a maximum speed of up to 20 miles per hour on flat ground with a 170 pound rider when powered only by that engine. (AB441, amending NRS 480, 482 and other sections)
Can I legally buy/build and ride an ebike that’s faster than 20 mph? Yes you can, but you need to know that the ebike is no longer considered equivalent to a bicycle and is subject to other state vehicular classifications. The definitions for electric bikes spanning 20-30mph, and 1-2 horsepower ranges, will vary from state to state, resulting in a no-man’s-land consensus about limits for motor vehicle definition. The common label for a 20-30mph, 2-wheeled vehicle with active pedals is a Moped. Other MVA labels include motor scooter, motorbike and dirt bike which may have equivalent power and speed performance, but do not have pedals to assist and move the vehicle.
It is important to note that if a vehicle has an electric motor greater than 500 watts and is capable of powering the vehicle when traveling at a speed greater than 32 km/h and it does not have a CMVSS compliance label it cannot be registered unless the owner can prove, by having the vehicle certified by an engineer, that it is safe for operation on NB highways. Also, not all vehicles are suitable for operation on NB highways and it could be that the vehicle in question may not be a motor driven cycle or a bicycle and cannot be operated on the highway at all.