Sunbeam S7 500 cc motorcycle, 1951.
© Science Museum / Science & Society Picture Library
Made by BSA (Birmingham Small Arms) Cycles Ltd at their Small Heath Works in Birmingham from 1948 to 1958, this machine designed by Erling Poppe has a self-contained engine and gearbox unit arranged for shaft drive. It is an example of the advanced design, on motor-car lines, which was adopted by a few manufacturers after 1945 as a progresive alternative to the long established single-cylinder, chain-driven type of machine. The large-section tyres, used in conjunction with the telescopic front forks and sprung rear frame, make the S7 one of the most comfortable motorcycles ever designed fro long-distance touring.