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
The first step in properly adjusting a front derailleur is to check the height. If the cage is too high above the chainring it is likely to shift poorly and if it is too low it is likely to bind on the chainring.
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.