The bottom bracket on a bicycle connects the crankset (chainset) to the bicycle and allows the crankset to rotate freely. It contains a spindle to which the crankset attaches, and the bearings that allow the spindle and crankset to rotate. The chainrings and pedals attach to the cranks. Bottom bracket bearings fit inside the bottom bracket shell, which connects the seat tube, down tube and chain stays as part of the bicycle frame.
Aerozine ceramic external bottom bracket bearing cups for BSC/ISO standard, that is M34.798×1.058 mm (1.37″-24 TPI) threads and a 68 mm wide bottom bracket shell
Plain bottom bracket shell of Royal Enfield Revelation houses Bayliss Wiley unit bottom bracket
Bayliss Wiley unit bottom bracket
Thompson bottom bracket
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