A motorcycle sidecar is a one wheeled vehicle that is attached to a motorcycle’s side. In this way, it transforms the motorcycle from a two-wheeled vehicle to a three-wheeled vehicle.
The first sidecar was meant to be a removable attachment that could be taken off whenever necessary, but modern versions are usually permanent attachments. The wheel of the motorcycle sidecar does not line up directly with the rear wheel of the motorcycle, and it's typically powered only by the motorcycle's rear wheel. This makes it different from a motorcycle trike, in which both of the rear wheels share a common axle.
The frame of the motorcycle sidecar is rigidly attached to the frame of the motorcycle on one of its sides. The other side is supported by the wheel. The body is usually large enough to fit one person, and it is also generally includes a trunk compartment in the back. Sometimes, the sidecar also has a removable soft top. Some models are designed only for carrying cargo, not a person.
Sidecars were particularly popular before the 1950s, during which time they provided users with a cheap alternative to cars. They are also commonly used by police and in the army. German troops often used them during World War II.
There are only a few companies that still specialize in manufacturing the motorcycle sidecar. MZ in Germany, Harley-Davidson in the United States, Dnepr in the Ukraine, IMZ-Ural in Russia, Izhmash in Russian, Chang Jiang in China, and Watsonian/Squire in Gloucestershire still produce them. Watsonian/Squire is the longest running manufacturer, and has been in business since 1912.
The motorcycle sidecar is also featured in many motorcycle races, and this class is included in events in Trial, Motocross, and Streetracing. These events are followed by fans in the United States, Europe, Australia, New Zealand, and Japan.