The front derailleur simply pushes the chain off one chainring and onto the next. It should shift smoothly, and the chain should not rub while pedaling.
A spring pulls the derailleur towards the inner chainring.
A cable pulls the derailleur towards the outer chainring.
There are four main steps :
1. Gap
2. Alignment
3. Limit Screws
4. Cable Adjustment.
Steps 1, 2, 3, are set-and-forget.
Step 4 is normal maintenance.
Tools : Allen Key and a Phillips-Head screwdriver.
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Step 1: Chainring Gap.
Check the gap between the derailleur and the outer chainring.
1. Move the derailleur to the middle chainring.
This positions the outer plate of the derailleur above the outer chainring.
2. The gap between the outer plate of the derailleur and the teeth of the outer chainring should be about 2 or 3mm.
3. To raise or lower the derailleur:
If a shifting cable is in place, loosen the tension on the cable by moving the derailleaur to the inner chainring.
Loosen the derailleur clamp bolt and move the derailleur either up or down the frame tube and re-tighten the bolt.
Move the derailleur again to the middle chainring and check the gap.
4. Repeat until the gap is 2 or 3mm.
Step 2: Chainring alignment.
Check the front derailleur cage is parallel to the chain.
1. Shift the chain to the outer rear sprocket and outer front chainring.
2. Look down on the front derailleaur. The derailleur cage should be parallel to the chain.
3. If the derailleur needs to be aligned:
If a shifting cable is in place, loosen the tension on the cable by moving the derailleaur to the inner chainring.
Loosen the derailleur clamp bolt, rotate the derailleur into position, and re-tighten the bolt.
Move the derailleur again to the outer chainring and check the alignment.
Note – Do not move the derailleur up or down as this would change the gap in Step 1.
4. Repeat until the derailleur cage plate is parallel to the chain.
Step 3: Adjusting the Limit Screws
There are two Limit Screws, marked “L” and “H”.
The screw marked “L” will stop the derailleur cage from moving past the inner chainring.
The screw marked “H” will stop the derailleur cage from moving past the outer chainring.
Note – If the screws are not marked :
Shift to the inner chainring and turn one of the screws back and forth a little.
If the derailleur moves this is the “L” screw.
If the derailleur does not move it’s the “H” screw.
1. Shift the chain to inner rear sprocket and inner front chainring.
Check the shifter cable is not tight.
If the cable is tight, turn the barrel adjuster into the housing until there is no tension on the cable.
If the cable is still tight, loosen the cable pinch bolt on the derailleur, and retighten pinch bolt.
2. Turn the pedals slowly while viewing the gap, stop at the tightest point in chainring rotation.
Adjust the “L” screw in or out until the gap between the inner cage plate and the chain is about 1mm.
3. Now shift the chain to the outer rear sprocket and outer front chainring.
4. Turn the pedals slowly while viewing the gap, stop at the tightest point in chainring rotation.
Adjust the “H” screw in or out until the gap between the outer cage plate and the chain is about 1mm.
Step 4: Adjusting the shifter-cable
1. Shift the chain to the inner rear sprocket and middle front chainring.
2. The inner cage plate and the chain should be as close as possible without rubbing.
Turn the pedals slowly to make sure chain does not rub at any point in the chainring rotation.
3. If the chain rubs on the inner cage plate, loosen the shifter-cable tension by rotating the barrel adjuster into the housing. Barrel adjuster is located at the shifter on the handlebars.
(see photo)
4. If the chain needs to be closer to the inner cage plate, tighten the shifter-cable tension by rotating the barrel adjuster out of the housing.
Note – If the barrel adjuster is all the way in or out and therefore no adjustment is available, the shifter-cable tension needs to be reset:
Shift to the inner front chainring.
Loosen the shifter-cable pinch bolt on the derailleur.
Turn the barrel adjuster all the way in.
Gently pull on the cable at the derailleur end, and retighten the pinch bolt.
Adjust the cable as shown above.
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That’s it, job done !
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