International meeting 1958 Rhein Cup: This is the special 309-pound 500cc solo BMW raced that year by the late Geoff Duke. It was powered by the carbureted version of the Rennsport racing engine, but there was also a fuel-injected option, making a bit more power claimed to be 58 hp at 9,500 rpm. Duke’s best finish on it was fourth in Belgium, just over a minute behind John Surtees on the MV Agusta four.



This was during BMW’s romantic involvement with the Earles long leading-link fork, whose extra mass projecting to the rear caused a slow pendulum-like wallow in long corners. BMW wasn’t the only one giving it a try. Looks like Girling units at the rear.



Note that final-drive torque reaction is not fed into the swingarm but into the link you see below it. This prevented the comical “pinion climb” that could result from rolling throttle on and off on production bikes. As you opened the throttle, rear suspension extended as the drive pinion “climbed” the axle gear. When you closed it, the rear of the bike sank. But not on this racing model. Years later, Dr. John Wittner would do the same for the shaft-drive Moto Guzzi in AMA Battle of the Twins racing.



What is that lump above the valve cover? That conceals the bevel gears driving this engine’s overhead cams. Built-for-racing, Rennsport engines like this one would win 15 consecutive sidecar world championships, 1954–’67, then five more in the years before two-stroke domination began in ’75.



Limited PR resources? This bike is posed for the photo by leaning it against a tree. In roughly the same period, Formula 1 cars were chugged through public streets to reach the starting grid at Belgium’s super-fast Spa circuit. TV had not yet turned sport into spectacle.

Volker Rauch