Mountain biking is the sport of riding bicycles off paved roads. It requires endurance, bike handling skills and self-reliance, and is usually performed on dirt roads, park trails and mountain trails.

Riders are often out in the countryside, far from civilization, so there is a strong ethic of self-reliance in the sport. The ability to repair broken bikes or flat tyres and avoid being stranded can also help.

Mountain bikes differ from road racing bicycles in several ways. They have a smaller and stronger frame, knobbly tyres on wheels that are wider, a lower range of gears to facilitate climbing up steep hills and over obstacles, a wider flat or upwardly-rising handlebar that allows a more upright riding position, and usually some form of suspension system for either the front wheel or both wheels.