A mountain bike or mountain bicycle (abbreviated MTB or ATB (all terrain bicycle)) is a bicycle designed for off-road cycling, including jumps, and traversing of rocks and washouts, and steep declines, either on dirt trails, logging roads, or other unpaved environments. Bicycles typically used for mountain biking need to be able to withstand off-road use and the surmounting of obstacles such as logs and rocks. Most mountain bikes use 26 inch (559 mm) bicycle wheels with wide, knobby tires for extra traction and shock absorption. In the current century, front wheel suspension has become the norm and full front and rear suspension has become increasingly common. Some mountain bikes are also fitted with bar ends on the handlebars to give extra leverage for hill-climbing.

Since the development of the sport in the 1970s, many new subtypes of mountain biking have developed, such as cross-country (XC) biking, all-day endurance biking, Freeride-biking, downhill mountain biking, and a variety of track and slalom competitions. Each of these place different demands on the bike requiring different designs to suit them. MTB development has included an increase in gearing, up to 27 speeds, to facilitate climbing and rapid descents. Other developments have included disc instead of cantilever or V-brakes.

History

Designs

Mountain bikes can be classified into four categories based on suspension:

• Fully rigid: A frame with a rigid fork and fixed rear, no suspension.
• Hardtail: A frame with a front suspension fork and no rear suspension.
• Soft tail: A frame with small amount of rear suspension, activated by flex of the frame instead of pivots.
• Dual or full suspension: A front suspension fork and rear suspension with a rear shock and linkage that allow the rear wheel to move on pivots.

Discipline-oriented designs

There are several different styles of mountain biking, usually defined by the terrain, and therefore bikes employed. All of the bikes in this category fall into one of the above four categories and bikes of each of the above style can be found almost any of the following categories.

Enduro/all-mountain (AM) bikes bridge the gap between cross-country and freeride bikes, typically weighing between 30 and 35 pounds (14 to 16 kg). These bikes tend to feature greater suspension travel, frequently as much as 6 inches (150 mm) of front and rear travel, often adjustable on newer mid- and high-end bikes. They are designed to be able to ascend mild-to-moderate inclines and descend steep declines, though their relatively heavy overall weight limits their utility in all-day rides involving steep climbs.