The engine of the Triumph Tiger 100 GP was actually ex-stock air borne generator engine. As it was used in a plane it had to be light and had ample finning for cooling. When the war ended Triumph found that they had some engines which the RAF did not require anymore. They decided to put the engine in a rigid frame, attached a close ratio gearbox and fitted a sprung hub at the rear for smooth riding. Light material was used extensively.