Linear bicycle derailleur

A derailleur for a bicycle for changing the speed of the bicycle, said bicycle being equipped with front and rear wheels, said rear wheel being fixedly attached to a series of parallel drive sprockets, said derailleur being controlled by a shifting mechanism, said shifting mechanism being located remote from said derailleur and being controllably attached to said derailleur by single or multiple looped control wire, said derailleur comprising an upper mount for attaching said derailleur proximate the drive sprockets of said bicycle, a pair of stationary parallel guide rods having first and second ends, said upper mount fixedly supporting said stationary guide rods at an angle between approximately 15.degree. to 75.degree. to horizontal, a cable housing mount fixedly attached to the second end of said guide rods, a pulley wheel assembly rotatably supporting upper and lower pulley wheels over which a drive chain is caused to pass for powering said bicycle, said pulley wheel assembly being rotatable at an axis established by the axis of said upper pulley wheel and being spring biased to take up slack in said drive chain and further being linearly slidable over said stationary guide rods in response to a change in sifter orientation and resulting movement of said looped control wire in either direction such that at any particular shift position a substantially single plane is created by a drive sprocket over which said drive chain passes and said upper and lower pulley wheels.