How to choose your MTB front derailleur?

As the number of front derailleur standards has multiplied in recent years, choosing your MTB front derailleur has become relatively complicated. Here is how to make the right choice for your mountain bike.

The standards

The number of speeds: 9, 10, 11 or 12
The number of chainrings: 1, 2 or 3
The type of fixing: clamp or direct mount
The pull type: top, bottom, front

Types of front derailleurs

Reminder: Unlike the MTB rear derailleur, SHIMANO and SRAM operate under the same standard for the front derailleur, meaning you can mix components from these two brands.

As all drivetrain components are designed to work under a speed and chainring standard, it is essential to respect it. For example, a front derailleur labelled "2x10S" will only be compatible with a 2-chainring, 10-speed drivetrain.

Of course, if you have opted for a single-chainring setup, you will not need a front derailleur.

Regarding the type of fixing, the most common is a clamp mount, with a diameter of 28.6 mm, 31.8 mm or 34.9 mm. This clamp is positioned above the derailleur for a "top clamp" A or below for a "bottom clamp" B.

There is another type, known as direct mount or "Direct Mount" C, in English. This requires a frame specifically designed for fitting this type of front derailleur. These frames come equipped with a plate that will accept the derailleur.

It is important to note that there are also variations: top direct mount, bottom direct mount and mid direct mount.

In the case of "top direct mount" (or "type-D" with Shimano), it is fairly straightforward — there is only one standard, easily identifiable since the derailleur is fixed to the bike by a single screw positioned above the derailleur.

In the case of "bottom direct mount", identifiable by the derailleur being fixed by two screws positioned below the derailleur, there are three versions:


Type S1 The distance a between the two screws is 42.7 mm	Type S2 The distance b between the two screws is 22.7 mm with a flat contact against the bike	Type S3 or Type-E The distance c1 between the two screws is 22.7 mm with an offset c2 of 5 mm between the two mounting points.

The mid direct mount, also known as centred direct mount, recently appeared in the SRAM product range.

Finally, there is one last type of mounting, now rare, which is the "BB-mount". The derailleur then has a plate allowing it to be positioned between the bottom bracket and the frame. This system was used for frames with geometries too particular to allow a derailleur to be fitted to the seat tube.

The cable entry point on the derailleur, known as the cable pull, can be routed in different ways:

Front derailleur Down Swing (top clamp) From above for a top pull / Top Pull A	Front derailleur Top Swing (bottom clamp) From above for a top pull / Top Pull A

Front derailleur Down Swing (top clamp) From below for a bottom pull / Down Pull B	Front derailleur Top Swing (bottom clamp) From below for a bottom pull / Down Pull B

Or from the front for a front pull c, in English Side Swing.

Reminder: some derailleurs accept both top and bottom pull.

Which front derailleur should you choose?

The choice will depend primarily on the standard required by your bike frame. Simply ensure you choose a derailleur compatible with your frame and suited to your MTB drivetrain.

For a clamp mount, the choice between top and bottom depends on the shape of your frame. On a full-suspension bike, for example, it is rarely possible to fit a top-clamp derailleur as it would foul the suspension linkage. If your frame allows both standards, the bottom clamp is generally stiffer and therefore more effective for gear shifting.

Découvrez tous nos conseils & Tutoriels