Motorcycle a three-speed gearbox and belt transmission. It was so popular with its users that it was nicknamed the "Trusty Triumph." By 1920, Harley-Davidson was the largest manufacturer, with their motorcycles being sold by dealers in 67 countries. In the 1950s, streamlining began to play an increasing part in the development of racing motorcycles and the "dustbin fairing" held out the possibility of radical changes to motorcycle design. NSU and Moto Guzzi were in the vanguard of this development, both producing very radical designs well ahead of their time. NSU produced the most advanced design, but after the deaths of four
V-twin engine the Princeps AutoCar Co (UK) advertised a V-twin engined motorcycle, and in 1903 V-Twins were produced by other companies, including the 90 degree XL-ALL (made by Eclipse Motor & Cycle Co in the UK). Also, in 1903, Glenn Curtiss in the United States, and NSU in Germany began building V-twin engines for use in their respective motorcycles. Peugeot, which had used Panhard-built Daimler V-twins in its first cars, made its own V-twin engines in the early 20th century. A Norton motorcycle powered by a Peugeot V-twin engine won the first Isle of Man Tourist Trophy twin-cylinder race in 1907. Most