A Zabel engined sidecar outfit.Sidecar racing, known as Sidecarcross has been around since the 1950s but has declined in popularity recently. This variant is common in Europe, with a few followers in USA, New Zealand and Australia. The premier competition, the Sidecarcross World Championship, is contested on European tracks only and almost exclusevly by Europeans.
Motocross sidecars are purpose built frames that resemble an ordinary motocross-cycle with a flat platform to stand on attached to either side and a handlebar at waist height to hold on to. The side of the "chair" (slang for the platform) usually follows the side of the road the nation in question drives upon, but not always. The passenger balances the bike by being a counterweight, especially in corners and on jumps. It is driven on ordinary crosstracks.
It is very physically demanding, especially for the passenger. This is reflected in most in the Swedish term for passenger - "burkslav", roughly translated as trunk/body/barrel-slave. This name comes from the early sidecars where the platform looked like a real road-sidecar and not today's platform.
The major frame builders today are VMC, BSU, AYR, EML and Woodenleg. Ordinary engines can be used, but size matters and two engines purpose built for sidecars exist, Zabel (Germany) and MTH (Austria) are most common. Four-strokes are getting more common, usually KTM (Austria).