About DERAILLEURS REAR
Derailleur systems were designed and built as far back as the late 1800s. A French bicycle tourist, writer and cycling promoter Paul De Vivie, invented a two speed rear derailleur in 1905 which he used on forays into the Alps. In recent years Campagnolo and Shimano are the two main manufacturers of derailleurs, with Campagnolo only making road cycling derailleurs and Shimano making both road and offroad. American manufacturer SRAM has been an important third, specializing in derailleurs for mountain bikes, and in 2006 they introduced a drivetrain system for road bicycles.