1st H-screw
The H-screw limits the swivelling range of the front derailleur to the right so that the chain cannot fall over the large chainring to the outside.
2nd L-screw
The L-bolt limits the operating radius of the front derailleur inwards. This prevents the chain from falling beyond the small chainring towards the bottom bracket when shifting.
3. tension clamp
Depending on the shape of the frame, the front derailleur can be articulated from above or below (dual-pull), or from the front (front-pull). In any case, the cable should be clamped with around six to seven Newton metres.
4. tensile stress
Turning the tension screw on the shift lever anti-clockwise increases the tension on the derailleur. This makes it easier for the chain to climb onto the larger chainring.
5 Change train
If you remove the small grub screw on the shift lever (Shimano), a new shift cable can be threaded in. The shift lever must be in its relaxed position - i.e. small chainring - for this.
Front derailleur mounting types
How the front derailleur is mounted on the mountain bike depends on the frame shape. Modern fully frames in particular often require special adapters. Another new feature is the option of side-swinging the front derailleur, which is primarily intended to reduce operating forces and offer manufacturers more space on the rear triangle.
Direct Mount High
The front derailleur is mounted on the frame without a clamp and the cage swivels downwards (down swing). The clamp has a small adjustment range. The front derailleur is also available as a side-swing version.
Direct Mount Low
Is also mounted on the frame, but the cage swings upwards (top swing). The modern side-swing version is also available here. Ensure that all direct mount models have the right tooth capacity.
High Clamp
Front derailleurs with clamp mounts are rarely found on modern bikes. They fit seat tubes with a diameter of 28.6 to 34.9 millimetres. High-clamp models are available as down-swing or side-swing versions.
Low Clamp
Front derailleurs with a low clamp position also only fit seat tubes with a diameter of 28.6 to 34.9 millimetres and swing upwards (top swing). The low clamp version is also available as a side-swing version.
ADJUSTING THE FRONT DERAILLEUR IN SIX STEPS
WORKSHOP TIPS
Alignment
The outer guide plate of the front derailleur should be exactly parallel to the chainring. Place an Allen key on the flat side of the large chainring and guide the Allen key along the guide plate by turning the crank. This makes it easy to check the position. Advantage of direct mount front derailleurs: They are always straight thanks to the fixed mount on the frame, even without fiddling.
Fully assembled
On bikes with rear suspension, the front derailleur position changes as soon as the rider sits in the saddle. The assembly and adjustment should therefore be carried out in the sag position. A tension strap helps to hold the rear shock in the sag position during setup.
2- or 3-gang conversion
Older gear levers have a so-called mode converter on the underside. The position of the small lever is selected depending on whether you are using two or three chainrings. Current shifters do not have this function. If you are riding in a double setup, the third shift position is simply not used.
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Stefan Frey
Editor
