MOTORCYCLE

any two-wheeled or, less commonly, three-wheeled motor vehicle, usually propelled by an internal-combustion engine. bicycle or tricycle propelled by an internal-combustion engine (or, less often, by an electric engine). The motors on minibikes, scooters, and mopeds, or motorized velocipedes, are usually air-cooled and range from 25 to 250 cubic cm (1.5 to 15 cubic inches) in displacement; the multiple-cylinder motorcycles have displacements of more than 1,300 cubic cm. The European method of rating an engine is by the volumetric displacement of the pistons in cubic centimetres. The horsepower method of rating is used in some countries, including the United States. A rough equivalent is 8 to 10 horsepower per 100 cubic cm. The first motor tricycle was built in 1884 by an Englishman, Edward Butler. The first gasoline-engine motorcycle to appear publicly was built by Gottlieb Daimler, of Bad Cannstatt, Ger., in 1885. The first practical engines and motorcycles were designed by the French and Belgians, followed by British, German, Italian, and American makers. The popularity of the vehicle grew, especially after 1910. During World War I the motorcycle was used by all branches of the armed forces in Europe, principally for dispatching. After the war it enjoyed a sport vogue until the Great Depression began in 1929. After World War II a revival of interest in motorcycles lasted into the late 20th century, with the vehicle being used for high-speed touring and sport competitions. Single-cylinder motorcycles, long dominant in the market, usually have four-stroke gasoline engines; but many smaller machines, both European and Japanese, utilize two-stroke engines below 250 cubic cm, which are more economical to run but need more frequent decarbonization. In many two-strokes, the fuel consists of a mixture of oil and gasoline. Most large modern machines use coil-ignition electrical systems, but magneto ignition is common on lightweight two-strokes. Transmission is normally through chain or gearing between engine and a two- to six-speed gearbox and then by primary chain to the rear-wheel sprocket. In some more advanced machines the final drive is via a shaft and bevel-gear system. Electric push-button starters have become common, largely replacing kick starters. Controls on handlebar grips govern the throttle action and often the front-wheel brake system as well; the rear-wheel brake is usually controlled by foot pedal, but these systems vary. Modern braking systems mostly utilize hydraulic disc brakes. Three-wheeled motorcycles with radio equipment located in a trunk mounted between the two rear wheels are used by some police departments. The practice of attaching auxiliary engines to bicycles in western Europe and parts of the United States led to the development during the 1950s of a new type of light motorcycle, the moped. Originating in Germany as a 50-cubic-centimetre machine with simple controls and low initial cost, it was largely free of licensing and insurance regulations except in Great Britain. The more sophisticated motor scooter originated in Italy soon after World War II, led by manufacture of a 125-cubic-centimetre model. Despite strong competition from West Germany, France, Austria, and Britain, the Italian scooters maintained the lead in the diminishing market. The scooter has small wheels from 20 to 36 cm (8 to 14 inches) in diameter, and the rider sits inside the frame. Power units are placed low and close to the rear wheel, which is driven by bevel gearing or chain. Capacities vary from 50 to 225 cubic cm, and four-speed gearing is common. Additional reading The terminology of motorcycle technology is given in the concise SAE publication A Dictionary of Terms for the Dynamics and Handling of Single Track Vehicles: Motorcycles, Mopeds, and Bicycles (1985). Eric Thompson and Laurie Caddell, From Motorcycle to Superbike: The History of the Motorbike, 2 vol. in 1 (1986), is well illustrated. Erik H. Arctander, The New Book of Motorcycles (1968), describes various types of the vehicle. George C. Cromer