How to Install a Shift Cable

Shift cables run from a bicycle's shifters to its derailleurs, relaying commands to change gears. They are thinner than brake cables, so they need to be changed regularly, otherwise they can rust, snap while riding or cause poor shifting. If a shift cable snaps, the derailleur will lose all of its tension, meaning the it will be stuck in the easiest gear on the front and in the hardest gear on the rear. Changing your shift cables will prevent this predicament.

Things You'll Need

  • 5 mm Allen wrench
  • Light lubricant
  • Cable cutters
  • Flat cutters
  • Crimp end
  • Sharpened bicycle spoke
  • Philips screwdriver
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Instructions

    • 1

      Shift into the gear with the least tension, depending on the cable you want to change. For a front derailleur, this is the easiest gear, while this is the hardest gear on the rear derailleur. Spin the barrel adjusters on the shifters and derailleurs all the way inward. Use your 5 mm Allen wrench to disconnect the cable from the derailleur by loosening the mounting bolt on the derailleur.

    • 2

      Open up the shift cable port on the shifter. This is usually a hole covered by a plastic screw on the side of the shifter that can be removed with a Phillips screwdriver. You should see the head of the cable. Hook your sharpened spoke under the cable's head. If the end of the cable is crimped, cut off the crimped end with your cable cutter. Pull the cable out from the shifter.

    • 3

      Pull off the pieces of stiff housing that hold the cable. Squirt a little bit of light lube down each end of the housing piece, then replace it. Insert the new shift cable into the cable port on the shifter and feed it through the housing and to the derailleur. Replace the cover of the cable port and tighten it with your screwdriver. While pulling it tight with your hands, tighten it under the mounting bolt using your 5 mm Allen wrench.

    • 4

      Shift through the gears with your shifter. If installed correctly, the shifter should feel smooth. You may also want to pull on the cable with your hand to stretch it out. This will help break the cable in. If there is a significant amount of slack in the cable (usually indicated by the derailleur being unable to shift into the next gear), loosen the mounting bolt and pull the cable tight, then tighten the mounting bolt again.

    • 5

      Cut the excess cable off the derailleur using your cable cutters. You should leave about an inch of excess cable, but you should exercise discretion depending on the position of the cable on your bike. Too much excess cable on some front derailleurs, for instance, can rub against the rear wheel. Insert a crimp end on the end of the cable and indent it onto the cable with your flat cutters.