https://en.wikipedia.org/wiki/Bicycle
WebA bicycle, also called a pedal cycle, bike or cycle, is a human-powered or motor-powered assisted, pedal-driven, single-track vehicle, having two wheels attached to a frame, one behind the other.A bicycle rider is called a cyclist, or bicyclist.. Bicycles were introduced in the 19th century in Europe. By the early 21st century, more than 1 billion were in existence.