Motorcycle was producing over 500 bikes. Other British firms were Royal Enfield, Norton and Birmingham Small Arms Company who began motorbike production in 1899, 1902 and 1910, respectively. Indian began production in 1901 and Harley-Davidson was established two years later. By the outbreak of World War I, the largest motorcycle manufacturer in the world was Indian, producing over 20,000 bikes per year. During the First World War, motorbike production was greatly ramped up for the war effort to supply effective communications with front line troops. Messengers on horses were replaced with despatch riders on motorcycles carrying messages, performing reconnaissance and acting
Motorcycle racing 1200 cc for twins, and between 750 cc and 1000 cc for four cylinder machines. The motorcycles must maintain the same profile as their roadgoing counterparts. The overall appearance, seen from the front, rear and sides, must correspond to that of the bike homologated for use on public roads even though the mechanical elements of the machine have been modified. Supersport racing is another category of motorcycle road racing that employs modified production motorcycles. To be eligible for Supersport racing, a motorcycle must have a four-stroke engine of between 400 and 600 cc for four-cylinder machines, and between 600 and