Triumph 4hp (1914 to 1925)

The 4hp model was introduced by Triumph Motorcycles in 1914. It featured a 550cc single-cylinder engine, a 3 speed manual transmission with a Sturmey-Archer rear hub and a tubular rocking fork frame. Its first version was known simply as the 4hp, while in 1915 the Model H was introduced, optimized for military use during the First World War, with a reinforced gearbox and kick start. The 4hp was widely used in both civilian and military versions, representing a milestone in the evolution of Triumph due to its greater power, reliability, and mechanical improvements over its predecessors, and laying the foundation for the brand's future models.