This patent covers the first Cyclo Benelux design, and is mainly concerned with the decision to off-set the pivot of the pulley cage from the line between the centres of the two pulleys. It explicitly mentions that this improves the shify by giving a more constant ‘chain gap’ - a simple fact that Tullio Campagnolo did not seem to fully grasp until 1963.

• Publisher: UK Intellectual Property Office
• Inventor: Louis Camillis
• Country: UK
• Date: UK application filed August 1949
• Derailleur brands: Cyclo Gear Company
• Derailleurs: Cyclo Benelux