Thus, in addition to producing agricultural tools and railway brake systems, BMW began manufacturing a flat-twin industrial engine known as the BMW M2B15, which was quickly adopted by various motorcycle manufacturers such as Victoria Werke AG and Bayerische Flugzeugwerke (which used it in the Helios model).
When BMW and Bayerische Flugzeugwerke merged in the early 1920s, a heavily reworked version of the Helios began production in 1923 under the designation R32 – the first motorcycle to bear BMW’s blue and white badge. It introduced two key features that would become enduring hallmarks of BMW motorcycles: horizontally opposed twin cylinders and shaft drive.
In 1935, BMW unveiled the R12 at the Berlin Motor Show – the first motorcycle in the world to feature a telescopic front fork as suspension, paired with a particularly rigid frame in a clear Art Deco style. The new Nazi regime immediately recognised in this elegant model several qualities suited to military needs: simple and robust construction, speed, shaft drive, and horizontally opposed cylinders with excellent thermal dissipation – ideal for extreme operating conditions.
It was thus decided to produce a military version of the R12, fitted with an Einvergasermotor (a single carburettor supplying the 745cc boxer twin engine, delivering 18 hp at 3,400 rpm, compared to the 20 hp at 4,000 rpm in the civilian twin-carburettor version). The aim was to equip Wehrmacht police units and provide a vehicle particularly well-suited for reconnaissance and liaison duties, including a popular version with sidecar.
Between 1935 and the end of R12 production in 1942, BMW built nearly 30,000 examples of the model. The earliest units were in fact civilian bikes later requisitioned in 1939, alongside some 10,000 purpose-built military versions.
From the campaign in Crete to North Africa and the frozen steppes of Russia, the R12 played a significant role in its designated functions, until it began to be replaced in 1942 by the BMW R75 – a motorcycle designed from the outset for military service.
Both the R12 and R75 would be copied directly or indirectly. The Americans – impressed by the advantages of shaft drive in desert conditions and the effectiveness of the hydraulically damped telescopic fork – quickly developed reverse-engineered versions of the suspension and drivetrain for their Harley-Davidson XA (for Experimental Army) and Indian 841. The Soviets, on the other hand, did not produce a mere copy but obtained a licensed design, agreed upon under the Molotov–Ribbentrop Pact of 1939. The model selected was the sophisticated BMW R71, featuring a tubular frame and rear suspension, used in small numbers by the Wehrmacht as an evolution of the R12. It was later produced by several factories in the Soviet Union as the Dnepr M-72 from 1941 into the late 1950s, and in China as the Chang Jiang CJ750 from 1957 through to the 1980s.