At the Brussels Motor Show in 1955, BMW debuted its R50 alongside their new new R60 and R69. It was a range of three air-cooled flat-twins. The R50 featured a 26 bhp 490 cc unit, while the R60 displaced 600 cc and made 28 bhp. The R69 was the more sporting version of the R60, and made 35 bhp. All three bikes featured a new frame with leading-link Earles front forks in place of telescopic forks, and a rear swing arm suspension with dual adjustable hydraulic shock absorbers rather than “plunger” rear shocks. The hard-tail rear end, though was retained so that use with a sidecar was still possible.

The new flat twin bikes were further developments of the the R51/3, R67 and R68 models that had seen BMW through a huge wave of success with 100,000 bikes sold since the end of the Second World War.

Power went to the rear wheel via an automotive-style diaphragm clutch, and the four-speed transmission featured three shafts and a sliding coupling on the driveline to accommodate the greater travel in the rear suspension. The engine was fed by dual Bing carbs, and the motor featured a 6-volt Norris magneto. Brakes were larger drums that featured two leading shoes in the front.

The economic downturn in 1957 was tough on BMW, who saw production plunge to 5,500 units compared to 26,699 just three years earlier. Still, BMW stayed afloat while other German manufacturers like Adler and Horex were forced to close shop as a result of the tough economic climate. A big part of BMW’s success was strong demand from the U.S. market, and 85 percent of BMW bike production was exported.

In 1960, the R50/2 and R60/2 were introduced and featured improved crankshafts and camshafts, harder piston rings and a stronger clutch. High-performance versions named the R50S and R69S developed 35 and 42 bhp, respectively. Hella turns signals were offered as an option, and were mounted at the end of the handlebars.

In the R50S, the redline had been increased from 5,800 rpm to 7,650, and reliability suffered as a result because the crankshaft tended to flex at such a high speed. BMW devised new cylinders, but they didn’t fix the problem and the company discontinued the R50S at the end of 1962. The next year, the R69S got a flywheel damper and that largely fixed the problem.

Telescopic front forks came in 1967 on the R69S and are generally considered more desirable. For sidecar use with the famous Steib “bullet” sidecars, however, Earles forks are preferred thanks to their separate adjustment.

While the majority of the 100,000 BMW twins produced from 1950-69 are black, optional colors included white, red, olive green and grey blue. If correct, these unusually colored examples are prized by collectors. There few images in the motorcycle world that are more famous, however, than a black BMW flat twin.