A bicycle is a pedal-driven, human-powered vehicle with two wheels attached to a frame, one behind the other. A person who rides a bicycle is called a bicyclist.
Bicycles were introduced in the 19th century and now number about one billion worldwide, twice as many as automobiles.They are the principal means of transportation in many regions. They also provide a popular form of recreation, and have been adapted for such uses as children’s toys, adult fitness, military and police applications, courier services, and competitive sports.
The basic shape and configuration of a typical bicycle has changed little since the first chain-driven model was developed around 1885.Many details have been improved, especially since the advent of modern materials and computer-aided design. These have allowed for a proliferation of specialized designs for particular types of cycling.
The invention of the bicycle has had an enormous impact on society, both in terms of culture and of advancing modern industrial methods.
A mountain bike 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.Bicycle wheels used on mountain bikes generally use 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.
