In 1938, a completely new range was launched with the types BMW R 51, R 61, R 66 and R 71. The most striking innovation was the plunger rear-wheel suspension which had proved so successful in the Six Day Race held in the previous year. The BMW R 61 replaced the BMW R 6, which had been the source of the side-valve 18 hp 600 cc engine, as the new two-cylinder entry-level model. Like all the models in the series, the BMW R 61 could be ordered with combined hand and foot-operated gear shift for a premium price, although the majority of customers decided to forego this very sluggish additional convenience.