Derailleur gears designed and built in the late 19th century. One example is the Protean two-speed derailleur available on the Whippet safety bicycle. The French bicycle tourist, writer and cycling promoter Paul de Vivie (1853–1930), who wrote under the name "Vélocio", invented a two speed rear derailleur in 1905 which he used on forays into the Alps. Some early designs used rods to move the chain onto various gears. 1928 saw the introduction of the "Super Champion Gear" (or "Osgear") from the company founded by champion cyclist Oscar Egg, as well as the Vittoria Margherita; both employed chainstay mounted 'paddles' and single
Derailleur gears clamp around the seat tube, below the front derailleur, and at least one attaches to the front derailleur mount. Derailleurs require the chain to be in movement in order to shift from one ring or sprocket to another. This usually requires the rider to be pedalling, but some systems have been developed with the freewheel in the crankset so that the chain moves even when the rider is not pedalling. The Shimano FFS (Front Freewheel System) circa 1980 was the most widespread such system. Chain-drive systems such as the derailleur systems work best if the chain is aligned with the