The purpose of these instructions is to help guide you through the process of properly adjusting the front derailleur on a bicycle. The process may vary slightly between different bike setups but you should still be able to use these instructions to get a good general idea of what to do.
These instructions will be very helpful to you if your bike is shifting poorly and you want to get it back into proper working order. You might be amazed at how well your bike shifts when you are done. You can also use these instructions if you are installing a new front derailleur and need guidance setting it up.
Some mechanical knowledge is helpful if you are doing this for the first time. But there is no better way to learn then digging in and trying for yourself! I used lots of pictures with callouts to complement the procedure to try and make the process as painless as possible.
The front derailleur simply shoves the chain from one front chainring to another. The cage on the derailleur is pulled outwards by the inner wire. A spring in the derailleur moves the cage inwards when the tension on the inner wire is relieved. A properly adjusted front derailleur will shift the chain between the front chain rings smoothly and without any binding. The cage should not rub on the chain when pedaling the bike.
Tools Required for the job (see second photo):
1. Hex Wrench (size may vary between derailleurs)
2. Screwdriver (usually #2 Phillips or straight blade)
Lets get started! Good luck and most importantly have fun!
*note: These instructions were adapted from Park Tool's Repair Help guide. The general process is very similar but I switched a few things up to try and make the process easier. I also added a lot of detailed pictures to help beginners through the process. A lot of people find Park Tool's instructions hard to follow at times.
Step 1: Front Derailleur Height
1. Shift the derailleur to the middle front chainring. This should place the outer cage plate of the front derailleur directly above the outer chainring.
2. The gap between the teeth on the outer front chainring and the lower edge of the outer cage plate should be about 1-2mm. A penny makes a great feeler gauge as it is about 1.5mm thick. The penny should just be able to fit in the gap. (see first photo)
3. To raise or lower the derailleur, first relieve the inner wire tension by shifting to the lowest chainring. Then loosen the derailleur clamp bolt and shift the derailleur either up or down and re-tighten the bolt. Shift back to the middle front chainring and check the cage height. (see second photo)
4. Repeat this process until the gap between the teeth on the outer chainring and the lower edge of the outer cage plate is about 1-2mm.
*note: Front derailleur clamps typically leave a mark on the frame, which is useful as a reference when changing the height.
Step 2: Front Derailleur Rotational Angle
1. Shift the chain to the outer rear sprocket and outer front chainring.
2. View the chain from directly above. The chain should be parallel to the outer derailleur cage plate. (see first photo)
3. If the derailleur needs to be rotated; shift down to the inner chainring to relieve tension on the inner wire.
4. Loosen the clamp bolt and rotate the derailleur to the correct position. Make sure not to change the height. Retighten clamp bolt. (see third photo)
5. Shift back to the outer chainring and observe the alignment. (see first photo)
6. Repeat the process until the derailleur cage plate is parallel to the chain
*note: Front derailleur clamps typically leave a mark on the frame, which is useful as a reference when changing the rotational angle.
Step 3: Front Derailleur Limit Screw Settings
If the screws are not marked, you will have to test them to figure out which is which. Shift to the inner front chainring. Select one of the screws and turn it clockwise then counter-clockwise. If the derailleur moves then this is the “L” screw. If it does not; test the other screw. The screw that does not move the derailleur is the “H” screw. Make note of which is which.
Step 4: Front Derailleur â Adjusting L-screw
2. Check inner wire tension, it should be loose. If the inner wire is taut then turn the barrel adjuster into the housing. If the inner wire is still taught then loosen the inner wire pinch bolt and relieve the tension. Retighten the pinch bolt. (see third and fourth photo)
3. Sight the gap between the inner cage plate and the chain. It should be about 1mm. (see fifth photo)
4. Pedal the bike slowly while sighting the gap. Set the clearance at the tightest point in chainring rotation. Set the clearance by adjusting the L-screw.
Step 5: Front Derailleur â Adjusting H-screw
2. Pull the inner wire with hand to insure the derailleur is resting against the H-screw. (see third photo)
3. Maintain pressure on the wire and inspect the gap between the chain and the outer cage plate. It should be about 1mm. (see third photo)
4. Pedal the bike slowly while sighting the gap. Set the clearance at the tightest point in chainring rotation. Set the clearance by adjusting the H-screw.
Step 6: Front Derailleur â Adjusting Indexing
2. The gap between the inner cage plate and the chain should be as small as possible without rubbing. Pedal the bike to make sure it does not rub at any point in the chainring rotation. (see first photo)
3. To reduce the gap, increase the inner wire tension by rotating the barrel adjuster out of the housing. (see second photo)
4. If chain is rubbing on the inner cage plate, decrease the inner wire tension by rotating the barrel adjuster into the housing. (see second photo)
5. If the barrel adjuster is all the way out or in with no adjustment available then reset the inner wire tension. Turn the barrel adjuster all the way in. Shift to the inner front chainring. Loosen the inner wire pinch bolt and pull the wire gently, retighten the pinch bolt. Begin adjusting the inner wire tension as shown above. (see second and third photo)
Step 7: Congratulations!
Your bike should now shift quickly and smoothly between the front chainrings.
I hope you found my instructions useful. If you have any questions I will be happy to answer them to the best of my abilities.
Have fun on your test ride!