A bicycle, also called a pedal bicycle or bike, is a pedal-driven vehicle with two wheels arranged one behind the other on a frame, operated by muscle power or motor assistance. The rider of a bicycle is called a cyclist. Bicycles were introduced in Europe in the 19th century. By the beginning of the 21st century, there were already over a billion bicycles.
This number far exceeds the number of cars, both in absolute terms and in terms of the number of individual models produced. Bicycles are the primary mode of transport in many regions. They are also a popular leisure activity and are used for various purposes: as children's toys, for fitness exercises, in military and police service, as courier services, in cycle racing, and for bicycle stunts. The basic form and configuration of a typical upright bicycle or "safety bicycle" has changed little since the development of the first chain-driven model around 1885.
However, many details have been improved, especially since the introduction of modern materials and computer-aided design. These developments have enabled a variety of specialized designs for different types of bicycles. The invention of the bicycle had an enormous impact on society, both culturally and in terms of the advancement of modern industrial methods. Several components that played a key role in the development of the automobile were originally invented for bicycles, including ball bearings, pneumatic tires, chain drives, and spoked wheels.
Although the terms "Fahrrad" and "Cycle" are often used synonymously and usually refer to two types of two-wheelers, they vary worldwide. In India, for example, "Cycle" exclusively refers to a two-wheeler powered by pedal power, while the term "Bike" describes a two-wheeler with an internal combustion engine or electric motor instead of a motorcycle.
Accessories: A touring bike is equipped with front and rear racks, fenders, bottle cages, four panniers, and a handlebar bag. Some components that are often optional accessories on sports bikes are standard equipment on everyday bikes and improve their functionality, comfort, safety, and visibility.
Fenders with spoilers protect cyclists and moving parts from spray when riding through wet areas. In some countries, fenders are also called mudguards. Chain guards protect clothing from oil on the chain and prevent clothing from getting caught between the chain and chainring. Kickstands keep the bike upright when parked, and bicycle locks deter theft. Front baskets, front or rear racks, and panniers mounted over one or both wheels are used to transport gear or luggage. Footrests can be attached to one or both wheel hubs to help the rider perform certain tricks or to provide an additional rider with a standing or resting place. Parents sometimes mount child seats at the rear, an additional saddle on the crossbar, or both, to transport children. Bicycles can also be equipped with a trailer hitch to pull a trailer for transporting luggage, a child, or both.
Toe-clips and toestraps and clipless pedals help keep the foot locked in the proper pedal position and enable cyclists to pull and push the pedals. Technical accessories include cyclocomputers for measuring speed, distance, heart rate, GPS data etc. Other accessories include lights, reflectors, mirrors, racks, trailers, bags, water bottles and cages, and bell. Bicycle lights, reflectors, and helmets are required by law in some geographic regions depending on the legal code. It is more common to see bicycles with bottle generators, dynamos, lights, fenders, racks and bells in Europe. Bicyclists also have specialized form fitting and high visibility clothing.
Standards
A number of formal and industry standards exist for bicycle components to help make spare parts exchangeable and to maintain a minimum product safety. The International Organization for Standardization has a special technical committee for cycles, TC149, that has the scope of "Standardization in the field of cycles, their components and accessories with particular reference to terminology, testing methods and requirements for performance and safety, and interchangeability".
The European Committee for Standardization also has a specific Technical Committee, TC333, that defines European standards for cycles. Their mandate states that EN cycle standards shall harmonize with ISO standards. Some CEN cycle standards were developed before ISO published their standards, leading to strong European influences in this area. European cycle standards tend to describe minimum safety requirements, while ISO standards have historically harmonized parts geometry.