For Little Englanders convinced that all good things in bicycling were invented in the satanic mills that once despoiled their green and pleasant land, the claim that the parallelogram derailleur was invented by Tulio Campagnolo has always rankled. How could a (presumably) feckless Italian, (presumably) spoiled from birth by an over-indulgent, pasta-cooking, mother, have been credited with such an achievement? Surely there is this UK Patent - clear and manifestly conclusive proof that English ingenuity had got there first - in 1945 no less. The fact that Nivex of France were selling parallelogram derailleurs in the 1930s can be quickly glossed over - every rule may be proved by an exception.
The Constrictor design described in this patent, and put into production in aluminium shortly afterwards, was highly original, rather elegant and virtually useless. By 1945 single pulley derailleurs were already becoming obsolete. Tulio Campagnolo, a few years later, developed a twin pulley derailleur which remains a clear and direct ancestor of today’s designs. Unfortunately for our warm-beer-drinking, cricket-loving friends, the Constrictor described in this patent is but an interesting cul de sac in the history of the derailleur.