This 1933 patent, with its childish drawings of a single pulley rear derailleur, may, just possibly, be the earliest manifestation of a parallelogram design.

The drawings do not look like the work of an engineer, and it is not clear if the design was ever produced. The inventor is Gaston Rivierre, a distinguished cyclist both as a professional and a 'vet', who was known to have a keen interest in derailleurs, and, indeed, in many aspects of bicycle technology.

• Publisher: L’Institut national de la propriété industrielle
• Inventor: Gaston-Louis-Clément Rivierre
• Country: France
• Date: French application October 1933
• Derailleur brands: Rivierre
• Derailleurs: unknown