Derny is the brand name of a French manufacturer, Roger Derny. The Company was founded in 1930 and closed in 1958. He was the inventor of the moped used in Bordeaux-Paris. The Derny is considered a hybrid; half-light motorcycle, half-bike. The speed of a Derny is controlled by pedaling. The faster you pedal, the faster the engine runs. This way the changes in speed are similar to the way a bicycle changes speed. Making it easier for the cyclist to draft behind it. The size is approximately that of a bicycle. The machine is equipped with a fuel tank located between the handlebars and the front wheel. It was first used in Bordeaux-Paris in 1938.
A 1952 Derny
The Derny, pictured above, features a hand-made steel frame and is equipped with a 2-stroke ZURCHER motor. The motor has a displacement of 90cc and produces 2 horsepower @ 2400 rpm. The front gearing is a single 60 tooth chainring. In the rear gearing has cogs of 14-17-21 teeth. A Cyclo 3 speed bicycle rear derailer changes the chain from cog to cog in the back. This Derny is equipped with a rear rack, a rear wheel stand and a pump.
Louison Bobet in Bordeaux-Paris 1959