These two cyclists ride their mountain bikes down a dirt trail. An American innovation in a sport historically dominated by Europeans, mountain biking originated in California in the early 1980s. Built to withstand the rigors of off-road trails in both recreational and competitive off-road cycling, mountain bikes utilize reinforced tubing, advanced suspension systems, and wide, knobby tires. Cyclists ride mountain bikes over terrain that is mostly inaccessible to the more fragile traditional road bikes.
Mountain bikes are designed for off-road riding, including climbing and descending steep inclines over rough terrain. The mountain bike, which took the entire bicycling industry by storm in the 1980s, introduced a whole new bicycle market as well as new competitive racing and touring events. Although initially the frames of mountain bicycles were designed with a touring geometry, by the late 1980s a sprightlier-handling racing geometry began to dominate the market. The frame of a mountain bicycle is usually somewhat smaller than a touring bicycle frame would be for the same rider. Like touring bicycles, mountain bikes usually have triple chain rings and 21 to 27 speeds with an emphasis on low gears. Mountain bikes also have cantilever brakes for increased breaking capacity. The wheels of mountain bikes may be exceptionally wide and the tires may have deep, knobby tread and use low pressures to increase their grip on uneven rocks and obstacles.