Although you’ll use your front derailleur less than the rear derailleur, ensuring it is set up correctly will save you the frustration of a dropped chain or chain rub.
Front derailleurs are straightforward components. A thin metal cage surrounds the chain and shifts your bike chain from one chainring to another.
However, performance can be impacted by small variations in cable tension, orientation of the cage and the position of the limit screws, so learning how to tune your front derailleur is useful.
In this guide, we explain how to adjust your front derailleur in five simple steps. We also cover how to set up electronic front derailleurs.
How to adjust your front derailleur
Tools required
- Allen or hex key set
- Phillips or crosshead screwdriver (older derailleurs)
1. Set the position
To set the orientation of your front derailleur, loosen the fixing bolt and adjust the cage until it is parallel to the chainrings when looking from above.
To set the height of your front derailleur, shift into the largest chainring. The outside edge of the derailleur should sit 2-3mm above the teeth of the chainring.
2. Set your lower limit screw
There will be two limit screws on your front derailleur – the one closest to the frame is usually the one that controls the lower limit. The lower limit screw adjusts how close the front derailleur’s cage can get to the frame.
Make sure your chain is on the smallest chainring and the largest cassette cog, then ensure there's no tension on your gear cable.
Turn the lower limit screw inwards and watch as the inside plate of the front derailleur’s cage moves towards the chain. You need it to be close, but not touching.
3. Indexing – set your cable tension
Loosen the gear cable anchor bolt. This is usually an Allen bolt, which pinches the cable to hold it against the front derailleur.
Pull the cable taut with your fingers and retighten the anchor bolt.
To test the tension, use the shifter to move up to the largest chainring. If the chain won’t shift or feels sluggish, twist the barrel adjuster to add tension to the cable by turning it anti-clockwise. Repeat the process until shifting is smooth and consistent.
If the chain refuses to shift into the largest ring, or if it overshifts and falls off, you need to reset your upper limit screw.
4. Set your upper limit screw
Change gear into the largest chainring and the smallest cog on the cassette.
Press on your front derailleur shifter to ensure there is tension on the gear cable and the derailleur is resting on the stop. Gently turn the outer limit screw until the inside plate of the front derailleur’s cage is close to, but not touching the chain.
If the chain refuses to shift up onto the big ring after you’ve adjusted the limit screw, it’s too far in and needs turning anti-clockwise. If the chain falls off over the big ring, your limit screw is too far out and you should turn it clockwise.
5. Trim
The design of bicycle drivetrains means some gear combinations on multiple-chainring setups can cause the chain to rub against the cage on the front derailleur, even if it's adjusted correctly according to the previous steps.
The solution is a small adjustment called trimming in order to move the front derailleur away from the chain, reducing noise, drag and wear.
Many shifters have a half-click (sometimes called a trim click), which allows the front derailleur to be trimmed automatically, should any rubbing occur on the cage.
As you shift down the cassette, it may be necessary to trim the front derailleur outwards, using the trim click, and as you shift back up the cassette, it may be necessary to trim the front derailleur inwards.
Once you’ve completed this step, your front derailleur should be set up correctly and shifting smoothly.
How to adjust an electronic front derailleur
Shimano Di2 front derailleur
Modern front derailleurs can be electronic, offering amazing benefits such as automatic trimming and zero cable wear.
Setting up a Shimano Di2 front derailleur is similar to a traditional cable-operated one, but with a few key differences.
Di2 derailleurs still have manual limit screws to be set up following the steps above. The clever programming in the derailleur’s electronic 'brain' should take care of the indexing (or ‘cable tension’ adjustment as it would traditionally have been) automatically.
However, if you find your Di2 front derailleur is out of adjustment, you can make small adjustments in the following way:
- To trim the Di2 front derailleur, shift into the small chainring at the front and largest sprocket on the cassette.
- Next, enter ‘adjustment mode’. That’s done on road bikes by pressing the button on the junction box until the red LED lights up. If you’ve got a display unit on your mountain bike, you can select adjustment mode here by pressing the display button once.
- Now you can use the shifter to fine-tune the front derailleur position until there is a very small gap between the chain and derailleur.
- Once you’ve made the adjustment, exit ‘adjustment mode’ by pressing the junction box/controller button again. Check that you can shift through all gear combinations without the front derailleur rubbing.
You can also connect your bike to a computer, phone or tablet and perform trim operations using Shimano’s E-Tube Project software.
For further information, check out our guide on how to set up a Shimano Di2 groupset.
SRAM AXS front derailleur
Adjusting a SRAM AXS front derailleur is similar to a conventional cable-operated front derailleur or a Di2 derailleur.
Like Di2 front derailleurs, AXS front derailleurs still have manual limit screws that need to be set up manually. Once that’s done, the indexing is taken care of via the factory programming of the AXS system.
SRAM AXS front derailleurs have an auto-trimming function, which should prevent the derailleur from rubbing on the chain.
However, if you need to adjust your SRAM AXS front derailleur, you can use either the AXS app or the shifter's AXS button:
- If using the AXS app: open ‘Drivetrain Settings’ and use the app to micro-adjust the front derailleur.
- If using your AXS shifter: press and hold the AXS button on the shifter while pressing the shift paddle at the same time to move the front derailleur inwards in 0.25mm increments.
You can learn more about electonic groupsets here.
Need more help with tuning your gears? Check out our guides on how to adjust your rear derailleur and how to fix common shifting problems.
