"German engineer Herr Richter experimented with a rocket-driven bike. 12 rockets were mounted on the rear wheel. The white box mounted on the crossbar held a battery that ignited the solid-fuel rockets. He made his attempt in 1931 at the Avus track in Berlin, reaching a speed of 90 kilometres per hour before being thrown off and the bike exploding."

          Via: Paris-Roubaix's photostream