Derailleur Gears - Use of Derailleurs

Use of Derailleurs

Derailleurs require the chain to be in movement in order to change ratio. Thus 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.

Chain-drive systems such as the derailleur systems work best if the chain is in line with the sprockets, especially avoiding the biggest drive sprocket running with the biggest driven sprocket (or the smallest with the smallest). The diagonal chain run produced by these practices is less efficient and shortens the life of all components, with no advantage from the middle of the range ratio obtained.