motorbike exhibits

Designed by Granville Bradshaw and produced by the Sopwith Aircraft Company, the ABC drew heavily on its designer’s wartime experience in the development of air-cooled aero engines. A ground breaking design, the ABC engine was an overhead-valve horizontally opposed twin with integral four-speed gearbox. Legend has it that the power unit was designed in under three weeks, but Bradshaw did not stop there, going on to draw up the duplex loop frame and sprung front and rear forks that marked out the ABC as one of the most advanced motorcycles of its day. It was fast too, J L E Emerson breaking the one-hour record twice at Brooklands, the second time at an average speed of 70.44mph, a feat that necessitated exceeding 80mph on occasions. Despite these successes, this promising design was hamstrung by production difficulties and price increases, just 3,000-or-so being made up to 1921 when the Sopwith factory ceased manufacture. This ABC was assembled new by Sir Len Southward when he was a Lad of 15, and by chance it came into his possession many years later, when he restored it to its present condition.