How to Fix a Front Derailleur That Is Rubbing

When rubbing occurs on a bicycle's front derailleur, the chain is hitting the inside of the metal cage on the device causing the rub. Rubbing affects the shifting negatively, as well as erodes the metal cage, reducing the life of the derailleur. Adjusting a front derailleur to stop the rubbing is done via the two adjustment screws on the backside of the derailleur. This chore is fixable using a small bicycle multi-tool that has a Phillips screwdriver.

Things You'll Need

  • 4mm Hex wrench (optional)
  • Phillips screwdriver
  • Penny
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Instructions

    • 1

      Check the height of the derailleur cage by sliding a penny in between the cage bottom and the teeth on the tallest chainring. The penny should slide between the two, confirming the derailleur is at the correct height. If there is more than 2 mm of space, the cage is too high. If you cannot get the penny slid between them, the cage is too low.

    • 2

      Change the height of the cage by using the 4 mm hex wrench on the screw holding the derailleur cable onto the derailleur itself. Loosen the screw, then pull up on the cable to raise the height, or pull the cable out by 2 to 3 mm to lower the cage. Tighten the screw.

    • 3

      Shift the bicycle into the largest chainring and gear. Look at the derailleur from the back and see what side the chain is rubbing (left or right).

    • 4

      Turn the screw marked "L" to move the cage away from the chain to the inside. Turn the "H" screw to move the cage to the right. Make the adjustments until the chain is squarely centered between the metal cage walls.

    • 5

      Check that there is a minimum of 1 mm space between either side of the cage to the chain when you shift through the entire range of gears. This eliminates all rubbing.