In 1951 Simplex had introduced the Simplex Juy 51, a derailleur that allowed the rider to vary the chain tension on the fly. In 1953 Huret had followed suit with its Luison Bobet model. Both designs used two cables and a double lever. This, 1955, patent covers the Cyclo Gear Company’s belated, and possibly somewhat reluctant, response - a design with a single lever and a cable that splits into to two - one operating the gear while the other increases the tension of the chain.

It’s a set up that seems almost inevitably destined to go out of adjustment, thereby failing to solve a problem that probably never existed. Fabulously futile.

• Publisher: UK Intellectual Property Office
• Inventor: Albert Edward Harris
• Country: UK
• Date: UK application filed August 1955
• Derailleur brands: Cyclo Gear Company
• Derailleurs: Cyclo Benelux Mark 12