How to Adjust Bicycle Deraileurs

The derailleur is a moving arm that controls the bicycle chain's position on multi-geared bicycles. The front derailleur is a rather simple cage that pushes the chain up or down between the front chain rings. The rear derailleur is a slightly more complicated arm that performs a similar action for the cassette while also tensioning the chain using a spring. A derailleur that is out of adjustment makes shifting through different gears difficult or impossible. Keeping a derailleur in proper adjustment allows the drivetrain to function properly, and gives you a full range of gearing options to overcome any level of incline.

Things You'll Need

  • Phillips-head screwdriver
  • Chain tool
  • Allen wrench set
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Instructions

  1. Adjusting the Front Derailleur

    • 1

      Set your chain on the largest chain ring, threaded through the cage of the front derailleur. Tighten the derailleur around the bicycle frame, but allow space for movement up and down for adjustment.

    • 2

      Adjust the angle of the clamp position on the front derailleur. When clamping the front derailleur to the frame of the bicycle, set the angle of the derailleur by looking down on the cage from above and setting it parallel to the center line of the frame.

    • 3

      Adjust the height of the front derailleur. The derailleur should be as low as it can be without hitting the chain as it travels around the largest chain ring, or approximately 2 mm higher than the teeth of the largest chain ring.

    Adjusting the Rear Derailleur

    • 4

      Adjust the low gear limit stop screw using the Phillips screwdriver. The low gear limit screw needs to be far enough that the derailleur arm lifts the chain to the largest cog on the cassette, but not far enough to throw the chain over the cassette into the spokes. This screw is usually marked with an "L."

    • 5

      Adjust the high gear limit stop screw using the Phillips screwdriver. The derailleur arm should travel far enough to get the chain onto the smallest sprocket of the cassette, but not far enough to push it over the gear and wedge it between the cassette and the frame. This screw is usually marked with an "H."

    • 6

      Adjust the index of the derailleur. This adjustment is done with a small knob located where the cable meets the derailleur. Start the adjustment in your highest gear.

    • 7

      Click the shifter once, to the next gear. If the chain doesn't travel to the next largest cog, turn the barrel of the adjusting knob forward a half-turn to tighten the cable. Try not to over-turn the adjustment screw.