Tools needed:
Keeping gear cables clean and lubricated, and replacing them if they fray, is very important for smooth shifting. Change them as a matter of course at least once a year, or more often if you are a heavy user.
Lubrication reduces the effects of friction between the inner cable and the cable housing, and helps to keep out water and grit. If the gears become difficult to shift to a different chainring or cog, the cable is probably dry and needs lubrication.
Friction increases with cable length. Cut cable housings as short as possible, but not so short that they constrict the cable or restrict the steering, If you are unsure how much cable housing to cut, look at the arc of the housings on other bikes.
Above: Parts of gear-shift units
Replacing a Shimano gear cable
(1) Place the gear-shifter in the smallest cog for the rear shifter
and the smallest chainring position for the front shifter.
- Pull back the brake lever and remove the old cable from a hole on the outer side of the lever.
- Insert a new lubricated cable into the hole.
- Ease the cable through the hole and insert it into the cable housing.
(2) Pull the gear cable through precut lengths
of cable housing with the needle-nose pliers.
- For the rear derailleur, this requires one length from the shifter to the cable guide on the down tube, and another length from the guide on the right-hand chainstay to the rear derailleur barrel adjuster.
- Place metal ferrules on the cut end of each housing so it fits snugly into the cable guide.
- Finally, pull the cable through the barrel adjuster and cable-clamp bolt. Then tighten the bolt with the Allen key.
Replacing a Campagnolo gear cable
(1) Remove
the handlebar tape because the cable housing runs underneath it. You
also need to do this if you are replacing a brake cable.
Carefully unwind the old tape from the center of the handlebar to just below the shifter and leave it hanging while you carry out the work.
Pull the rubber brake hood cover forward to free the tape beneath it. Pull the tape off slowly.
(2) Put
the rear shifter in the smallest cog and the front shifter in the smallest
chainring.
- Remove the old cable from under the hood cover.
- Grease the new cable and push it through the hole under the hood cover.
(3) Dribble oil into
a cable housing, which should be cut to fit between the cable guide and
the component. If it is cut too short, it constricts; if it is too long,
it increases friction.
- Ensure that metal ferrules are placed on the ends of all the cable housings on your bike.
- Insert the cable into the housing. Keep the cable to the derailleur under tension as you clamp it.