bicicttes

A bicycle, often called a bike, is a human-powered vehicle with a frame, two wheels, a crankset connected to a chain, and handlebars for steering. Propulsion is produced by pedaling, which drives the rear wheel through a drivetrain. Bicycles are used for transportation, recreation, sport, and utility, and they vary in size, materials, and purpose.

Bicycles began in the 19th century. The first practical two-wheeler was the draisine, or Laufmaschine, by Karl Drais in 1817. In the 1860s pedal-driven velocipedes appeared, followed by high-wheeled penny-farthings. The modern safety bicycle, with equal-sized wheels and a chain drive, emerged in the 1880s. Mass production soon spread globally, making bicycles affordable for many people.

Typical bicycles include a frame, fork, two wheels, a chain-driven drivetrain, brakes, a saddle, and handlebars. Frames use steel, aluminum, carbon fiber, or titanium. Drivetrain components include the crankset and gears; brakes may be rim or disc. Wheels and tires vary by riding style, and geometry affects handling. Many bikes include accessories and, increasingly, electric assist motors.

Common types include road bikes for pavement, mountain bikes for off-road use, touring bikes for long trips, hybrid or city bikes for everyday commuting, BMX for tricks, and folding bikes for compact storage. Each type emphasizes different frames, tires, and gearing to suit its use.

Bicycles are energy-efficient, affordable transport that can reduce emissions and congestion. They require relatively little infrastructure and offer health and mobility benefits. Safety practices, such as proper lighting, helmets, and maintenance, help prevent accidents.