Bicycle with DKW auxiliary engine, 1921
Based on what was originally a toy engine, DKW developed an auxiliary bicycle engine that became a great success in the early 1920s. It was a 118 cc two-stroke engine, originally developing 1 horsepower, later with a displacement of 143 cc up to 2.25 horsepower, and was mounted behind the bicycle‘s saddle. This miniature power unit soon proved to be so straightforward and reliable that the public nicknamed it “Das Kleine Wunder” – the little marvel – a play on the company‘s initials. By the end of 1922 about 30,000 of these engines had been sold.