Rocket propulsion was one of motorcycling's more predictable dead-ends. Promoted by Opel's head of testing (and grandson of the company's founder) Fritz von Opel, 1928's 'Monster' was based on the firm's Motoclub, and as such was powered by a conventional 500cc single from 0-75mph.
From there six powder-filled rockets (ignited in stages by a foot pedal) would propel the bike to a projected top speed somewhere north of 130mph. But the plan was halted by German officials on what we would now recognise as heath and safety grounds, and the Monster was restricted to demonstration runs – where it always managed to produce far more smoke than speed.
That same summer Fritz also created a rocket train (which exploded) a rocket plane (which also exploded) and drove this rocket car packed with 24 rockets and enough propellant to fell a block of flats, to 143mph. He left the family firm, and Germany, in 1929.