The first single-cylinder BMW motorcycle was the 1925 "BMW R 39", which was BMW's smallest model and used a engine. It was not successful and was discontinued in 1927. The next single-cylinder motorcycle was the BMW R 2, which was released in 1931. It used a engine and could therefore be ridden in Germany without a motorcycle licence at that time. The lineage of single-cylinder motorcycles continued with the "BMW R 4" in 1932 and the "BMW R 3" in 1936.