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.
There are an estimated 33 million adult cyclists in the United States, and the popularity of the sport at the recreational level continues to grow. This popularity has resulted from the country's ongoing interest in physical fitness, the international success of such American cyclists as Greg LeMond (winner of the Tour de France in 1986, 1989, and 1990), and the search for more efficient, economical, and environmentally friendly modes of transportation. Road riding and touring were especially popular in the United States during the 1970s and the mid- to late 1980s, but mountain biking superseded them in popularity during the 1990s.
Since bikes do not have turn signals, bicyclists need to use hand signals to indicate their intentions to drivers or riders behind them.