A motorbike

A motorized bicycle is a bicycle with an attached motor used to assist with pedaling. Generally considered as a vehicle, sometimes as a motor vehicle or a class of hybrid vehicle, motorized bicycles are usually powered by electric motors or small internal combustion engines. Some can be propelled by the motor alone if the rider chooses not to pedal, while in others the motor will only run if the rider pedals. Different regulatory authorities use a variety of names and classifications^[1].

Early motorized bicycles were powered by internal combustion (IC) engines. As electric motors have become lighter and battery storage density higher, the electric motor has recently seen an increase in popularity.

Motorized bicycles are distinguished from motorcycles by being capable of being powered by pedals alone if required. Many motorized bicycles are based on standard bicycle frame designs and technologies, although the modifications to the design to support motorisation may be extensive.

In countries where there is a strong bicycle culture (notably in Asia), the motorised bicycle is particularly popular; in 1996 Shanghai had 370,000 motorized bicycles, and 470,000 other vehicles^[1].

Wikipedia