BMW, which stands for Bayerische Motoren Werke, motorcycles are synonymous with flat-twins. The very first BMW motorcycle was the R32 in 1923.
BMW has not been actively involved in racing efforts in recent years, but has a long history of racing and record breaking. One of their most famous Early Riders was Ernst Henne, who set many speed records on streamlined, supercharged boxers in the 1930s. A BMW supercharged 500cc flat-twin, was rode by Schorsch Meier when he became the first foreign rider to win an Isle of Man TT in 1939 competing in the Senior class.
Following the collapse of its aero engine business after WWI, BMW turned to other areas of manufacture, motorcycles among them. Its first two models, marketed as the Frink and Helios respectively, were failures but a successful proprietary engine was supplied to other manufacturers, such as Victoria. Designed by Chief Engineer Max Friz and launched in 1923, the first motorcycle to be sold as a BMW - the BMW R32 - featured a 493cc, twin-cylinder, side valve engine having horizontally opposed cylinders, and this 'flat twin' layout would forever be associated with the marque.
BMW's M2B15 proprietary engine was a 'flat twin' but one designed for installation fore-and-aft, a layout that made for a lengthy wheelbase. Turning the engine across the frame, as seen in the Granville Bradshaw-designed ABC, seemed like a better arrangement, and with the crankshaft now inline, the adoption of shaft drive was the logical choice. Setting a pattern that endures to this day, BMW's first motorcycle was relatively expensive but superbly engineered and constructed, while the quality of finish was of the highest order. It was an immediate success - some 1,500 leaving the Munich factory in 1924 - and the R32 would continue in production, updated with an internally expanding front brake, until 1926.