The BMW R2 was a 198 cc overhead valve single-cylinder motorcycle produced by BMW between 1931 and 1936, the smallest motorcycle ever to enter series production with the firm (In 1948, a 125cc 2 stroke flat twin, designated R10, was developed but did not enter production).

Despite its much smaller design and engine capacity, the R2 retained many features of the larger boxer twin motorcycles in the range, such as cardan shaft drive and a pressed-steel duplex frame.

[2] Following the collapse of the Weimar Republic economy during the Wall Street crash of 1929, BMW's premier large capacity, expensive motorcycle range was hard hit, with fewer customers able to afford their premium purchase costs.

In all models, the 198 cc overhead valve four-stroke engine was mounted in a pressed-steel frame.

[4] The engine was offset toward the right of the frame, to allow it to drive the rear wheel directly when in top gear.