Mountain bike derailleur: everything about the mountain bike derailleur

To be able to switch the bicycle chain from your mountain bike to other sprockets, a derailleur is needed. There is a front and a rear derailleur if the mountain bike has multiple sprockets both front and rear. However, mountain bikes are nowadays in many cases only equipped with a rear derailleur. On this page I tell you everything you need to know about the MTB derailleur.

What is the MTB derailleur?

Every mountain bike has multiple gears. When you shift, the bicycle chain is moved to a different gear, in other words: the MTB chain is moved to another sprocket on the cassette. The derailleur is required to move the bicycle chain. This moves the chain to a larger or smaller sprocket by moving horizontally.

mountain bike derailleur
An MTB derailleur (Shimano Deore). © MTBdex.com

The mountain bike derailleur is part of the drivetrain. The complete powertrain consists of the following parts:

  • MTB shifters
  • crankset
  • MTB chain
  • MTB cassette
  • Derailleur(s)

Mountain bikes increasingly only have a rear derailleur

As I mentioned in the introduction, mountain bikes are always equipped with only a rear derailleur. It is true that this gives you ‘less gears’, since you only have one chainring for it. With fewer gears you have to perform fewer actions and the chance of a misstep is much less great.

In addition, it is of course also a big plus in terms of weight: you only have one shifter (switch) and one derailleur.

MTB Derailleur with clutch

A mountain bike takes a lot of hits on the various MTB routes. To ensure that a derailleur can better absorb these blows, there are also variants with a so-called clutch. If you close this, the derailleur is less flexible and it can bounce less quickly.

This is a big advantage during a rough ride, because the chain is less likely to come off. Adjust the MTB derailleur? Make sure that this clutch is open.

Buying a new mountain bike derailleur: buying tips

If you are going to buy a new mountain bike derailleur, there are a number of things you should pay attention to. For example, it is important to buy a derailleur that is suitable for the cassette (so look at the number of sprockets). Check out these and other helpful buying tips below:

  • If possible, buy the drivetrain in a set, so you can be sure that everything is compatible with each other
  • Just buy a derailleur? Go for the same brand as other powertrain components
  • Check whether the MTB derailleur is suitable for the current MTB cassette (look at the largest cassette ring)

It remains smart to opt for an established brand. Think Shimano or SRAM.

FAQ: Frequently asked questions about a bicycle derailleur

Why does a mountain bike now only have a rear derailleur?

With a front and rear derailleur, many gears overlap. By only having a rear derailleur you reduce the chance of a misstep and the range is almost the same. In addition, this is also an advantage in terms of weight.

What are good derailleur brands?

There are two popular brands that develop derailleurs: Shimano and SRAM. If you buy a new powertrain, I would recommend these brands.

What is a derailleur clutch?

A clutch ensures that the derailleur can better absorb hits. It will go up and down less, so that the chain can also fly off the mountain bike less quickly.

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