A motorized bicycle is a bicycle with an attached motor or engine and transmission used either to power the vehicle unassisted, or to assist with pedalling. Since it sometimes retains both pedals and a discrete connected drive for rider-powered propulsion, the motorized bicycle is in technical terms a true bicycle, albeit a power-assisted one. Typically they are incapable of speeds above 52 km/h (32 mph), however in recent years larger motors have been built, allowing bikes to reach speeds of upwards of 72 km/h.
A VéloSoleX motorized bicycle
1897 Millet motorcycle, showing the common ancestry of motorized bicycles and motorcycles. Note the radial engine built into the back wheel.
1948 American Flyer Whizzer-powered motor bike on display in the Martin Auto Museum
Derny motor-pacing cycle (motor mounted in frame, drive via chain to rear wheel)
A bicycle, also called a pedal cycle, bike, push-bike or cycle, is a human-powered or motor-assisted, pedal-driven, single-track vehicle, with two wheels attached to a frame, one behind the other. A bicycle rider is called a cyclist, or bicyclist.
The most popular bicycle model—and most popular vehicle of any kind in the world—is the Chinese Flying Pigeon, with about 500 million produced.
Women on bicycles on unpaved road, US, late 19th century
A penny-farthing or ordinary bicycle photographed in the Škoda Auto museum in the Czech Republic
The Svea Velocipede by Fredrik Ljungström and Birger Ljungström, exhibited at the Swedish National Museum of Science and Technology