90 Years of BMW Motorrad. The R 39 – BMW's first single-cylinder motorcycle…
Two years after the reliable R 32 came to the market, BMW's first serious race ...
90 Years of BMW Motorrad
The R 39 – BMW’s first single-cylinder motorcycle… Two years after the reliable R 32 came to the market, BMW’s first serious race victories are recorded by the R 37, a modified model with 16 HP sports engine. Then in the same year, BMW unveils the 250cc, single-‐cylinder R 39 sports model in a bid to win new customers…
BMW’s very first motorcycle – the R 32 – featured an uprated version of the horizontally-‐opposed four-‐stroke flat-‐twin engine that had been delivered to other manufacturers before the company decided to build its own complete motorcycle. Manufactured from 1923 onwards, it quickly gained an exceptionally high reputation for quality, but it was the price of 2,200 Reichsmarks that made it one of the most expensive motorcycles on the German market and this put it simply out of reach of most people. The racing derivative of the R 32 – the R 37 – cost even more to buy with a sales price of 2,900 Reichsmarks. With double the power of its predecessor, it took the brand into all sorts of motorsport competitions across the world, but the simple fact that it was unashamedly the most expensive motorcycle in the German market prevented it becoming a sales success and only 152 were produced in its lifespan. What the company needed was a model to win over less well-‐to-‐do customers and as a result, the single-‐ cylinder R 39 was added to the programme in 1925. BMW’s first single-‐cylinder machine was conceived as a sports model, with shorter wheelbase, pressed-‐in cylinder liners in the upper half of the housing, the same cylinder
head as the sports R 37 and, for the first time, an outer-‐shoe brake on the drive shaft flange. Its 247cc engine was, in reality, half a boxer twin with the cylinder moved to an upright position, but its performance was strong, with 6.5 HP being more than a match for the heavier R 32 and propelling it to an impressive top speed of 100 km/h (62 mph). It also sipped fuel at a miserly 2.5 litres per 100 kilometres of riding – outstanding economy figures by any reckoning. With a sales price of 1870 Reichsmarks, it was considerably less to buy than the two aforementioned models, but it shared the same build quality and reputation for reliability as its more expensive stablemates. It was unveiled at the German motor show in Berlin in December 1924 and just like the R 37 that had been introduced at the same time, the R 39 with its overhead-‐valve engine proved to be highly successful in motorcycle racing. In fact, in its first full year of competition, Josef Stelzer rode it to success in the 1925 German 250cc Championship.
Josef Stelzer on the R 39 in 1925
This undoubtedly helped sales too, as over the course of its lifetime (1925-‐1927) 855 units were produced – more than five times the amount of the R 37 – proving that there was a healthy demand for a usable, keenly-‐priced motorcycle built along the same foundations as the other two models in the line-‐up. As successful as the single-‐cylinder R 37 was, plans were already complete and another exciting new BMW motorcycle model was just ‘around the corner’. It would be known as the R 42. Designed to replace the original R 32, it would become a massive success for BMW, selling more units than the previous three models combined. But that’s another story…