bicycle, two-wheeled steerable machine that is pedaled by the rider's feet. On a standard bicycle the wheels are mounted in-line in a metal frame, with the front wheel held in a rotatable fork. The rider sits on a saddle and steers by leaning and turning handlebars that are attached to the fork.

A bicycle (or bike) is a small, human powered land vehicle with a seat, two wheels, two pedals, and a metal chain connected to cogs on the pedals and rear wheel. A frame gives the bike strength, and the other parts are attached to the frame.

Instead of using gasoline or diesel fuel like motorized vehicles, bicycles turn our energy, created by our bodies, into kinetic energy . A bicycle can convert up to 90% of a person's energy and movement into kinetic energy, making it the most efficient transportation mode to date.

On a straight path, a bicycle has two forms of motion: rotational and rectilinear. The motion of an item around a circular route in a fixed orbit is known as rotational motion. Rectilinear motion is the movement of things along a straight line.