In 1938, the R 51 added rear suspension to Rudolf Schleicher’s revolutionary R 5 of 1936 which had introduced an arc-welded steel tube frame, foot-operated shifter, and an overhead valve boxer twin. The R 51 seen here is a customer-racing SuperSport model, with a race-prepped engine, racing exhaust, and close-ratio four-speed gearbox, plus the optional larger tank. It was sold when new to English privateer Tim Reid, who joined the BMW factory team at the Isle of Man in 1939 but DNF’d. His family kept the R 51 SS in original, running condition for 60 years before selling it to California enthusiast Michael Nelson.

For more pictures and information on this or any other vehicle in the Motorcycles exhibit, check out the exhibition book in our store!