Derailleur

As derailleur is called the bicycle, the front shifting device at derailleurs. The front derailleur controls the running of the chain on the front two or three chainrings.

Until the 1960s, the chain exchange was customary means of a so-called About thrower. This turned axially (parallel to the crank axis). In addition, no Bowden cables were used, but the circuit is actuated directly by hand or foot.

Meanwhile, the derailleurs are built just like the derailleurs with parallelogram and operated with a shifter and a spring: when tensioning the chain of the train is pushed to the next larger chainring, and this process is facilitated by climbing aids on the chainrings; while solving the train a spring pulls the chain to the next smaller chainring.

Are classified according to the derailleur capacity, good models can turn differences of more than 15 teeth. For mountain bikes ( 3x9 ) a capacity of 22 teeth ( gradation 22-32-44 ) is common.

Classification

Derailleurs are usually divided by the type of installation and cable routing.

Cable routing

Top Pull - Pull Down

There are models with shift cable from the top ( Top Pull - mostly on the mountain ) and from below ( Down Pull - Road ). Many models are also available as dual pull version. This is a cable routing of the bottom or top (depending on the frame).

Assembly

Top Swing - Downswing

Furthermore, a distinction is made depending on the position of the mounting bracket between the (classical) Down Swing models in which the parallelogram cage hangs below the clamp, and the so-called Topswing models whose axis of motion for the cage is above the clamp. The main reason for the introduction of Topswing front derailleur are newer forms of bicycle frames, in which the classical Down Swing front derailleur for example, by a non-continuous seat tube can no longer be fixed.

E-Type

This type of derailleur is mounted between the bottom bracket and frame. It eliminates a clip which has to be fixed to the frame. This allows a further increase in the variety of frame designs. Some full-suspension frames have a " Umwerferstummel " where the derailleur can be mounted. This is not necessary when using E-type front derailleurs. The selection of E-type front derailleur is usually limited.

Direct Mount

The front derailleur is fixed by screws directly to a predetermined position on the frame.