How to adjust a front derailleur:
Before you adjust your front derailleur, make sure that the rear one is working properly. For this job, all you will need is a 5mm allen wrench, a phillips head screwdriver, chain lube, and a shop rag.
Equipment check: look over cable and housing. If it is frayed or broken then you need to replace it. Make sure your shifter is working by detaching the cable and shifting through all the gears. Check your derailleur to see if the cage is bent. The outside of the cage should run in a straight line. Check for overall wear on the derailleur by giving it a little wiggle. If it has a lot of play, then the springs and pivots are most likely worn and the whole derailleur should be replaced.
The outside of the front derailleur cage should run in a straight line with the chain
Placement & alignment: make sure the derailleur is in the right location by looking at it from the side view. It should be 1-2mm above the biggest chainring when it is shifted out there. Next, make sure that the cage is aligned with the chainring. Look down from the top to see that it runs parallel with the chainrings. Changing the placement or alignment is done by loosening the front derailleur clamp bolt and moving it by hand to the desired location.
The front derailleur should sit 1-2mm above the largest chainring
Low limit adjustment: this keeps your chain from falling off to the inside. Start by shifting the rear derailleur into the lowest gear. Now use the low limit screw to move the derailleur just until it touches the chain, then back it off 1 mm. Once this is done you are ready to reset the cable and cable tension.
Cable tension: start by closing any barrel adjusters and clicking the shifter into the lowest gear. The derailleur should have an obvious notch in it to show where the derailleur should be clamped. Pull the cable tight with your fingers and clamp it to the derailleur. Remove any slack by opening the barrel adjuster.
Adjust front derailleur cable tension with allen wrench
High limit adjustment: used to make sure your chain doesn’t shift off of the biggest ring. Turn the high limit screw just until the derailleur touches the chain, then backlit off a mm. Now put a little chain lube on the pivot points and try out your shifting.
