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Cable Replacement

A worn brake cable -- or damaged cable housing -- makes it harder to apply the brakes, and can keep the brakes from rebounding fully away from the rim. Damaged derailleur cables make shifting to a smaller cog or smaller chainring unreliable.

If the cable is only dirty, it can be cleaned out, and may work good as new. See our section on cable cleanout.

Check the cable housing (the sections of big black tube that surround the cable).  If you see a sharp bend, the housing needs to be replaced. Look at the exposed sections of cable. If you see fraying, breaks in the individual wires, or loosened wires, the cable itself must be replaced.

To replace a cable, buy a new cable, a section of cable housing, a cable end-cap, and housing end-caps. First thing you should know: brake cable housing has metal wrapping that goes in a circle around the cable, while derailleur cable housing has metal strips that run the length of the cable. Derailleur cable housing has a smaller hole (for the smaller cable) than brake cable housing. Don't substitute one type of cable housing for the other!

Undo the cable at the far end (at the brake mechanism or at the derailleur) by loosening the bolt on the retaining clip. Remove the cable end-cap by compressing it on the sides opposite the crimp with needle-nose pliers, or simply cut the cable.

Slide the cable housing caps away from the housing. Now slide caps and housing off the cable.

As you remove the old cable, place the parts in a line, so you can easily see where everything goes. Even if you're planning to replace the housing, keep the old sections so you can cut the new pieces to match!

Remove the old cable from the handlebar end.

Brake Cable: With the cable loose, pull the lever all the way back to the handlebar. This should expose a retaining clip, or a hole in the handle itself, that contains the barrel on the end of the cable.

Pull the barrel out of the retainer by lining it up with the slot in the clip.

If you have slots in your cable-tension adjuster and in the housing of the lever, you can simply slide the cable out the side of the housing by lining the slots up. Otherwise, pull the entire length of the cable out of the brake.

Brake cable being pulled out of the retaining clip.

Index Shifter with cable-access cap: An access port makes cable replacement easy (example, Shimano XTR shifters). Locate the cable cap. Unscrew it to expose the shifting mechanism.

Shift into the smallest cog or chainring (where the cable will be the most loose). You'll see the end of a cable-barrel rotate into view.

Shove back on the cable so the barrel comes out of the shifter mechanism. Grab the barrel and pull the cable through.

 

Index Shifter without access port: Click the shifter down into the smallest cog or chainring. Unscrew the bolts on the underside of the shifter. You may need a jewelers screwdriver.

(In most cases, removing the bolts on the gear indicator gauge won't expose the cable housing. But if you can't see any other way to disassemble the shifting unit, try it.)

Once the you're into the guts of the unit, push back gently on the cable until the barrel comes out of the retainer. Now grab the barrel and pull the cable out.

While you're at it, clean the exposed surfaces, and clean the cable pathway into the barrel adjuster.

Grip Shifter: Pull the hand grip away from the shifting grip. (Wet the inside of the grip to make it slide.) Or, loosen the brake and shifter attachments so you can slide the shifter away from the handgrip.

While pulling the shifting knob away from the body of the shifter, rotate until you find the position where the shifting knob will pull away from the housing.

Push backwards on the cable to pop the barrel out of the shifting grip. Take a long look at the path of the cable, so you can put the new cable back on the same course.

Grab the barrel and pull the cable out of the shifter.

While you're at it, clean up the inside of the shifting mechanism. Grip shifters tend to accumulate a lot of dirt and sand.

Cut the sections of new cable housing to match those you're replacing. A Dremmel tool is good for getting a clean cut through the metal of the housing. A cable-cutting tool will also make a nice slice through the housing. A fine-toothed hacksaw will do.

Insert the new cable through the mechanism at the handlebar, making certain it's seated properly in its retainer. Then begin assembling the sections of cable housing onto the cable.

Slide on the front end cap, cable housing, and back end caps for each section of housing. Fit the housing into the mountings at the handlebars, and at each relay mounting of the frame.

Dial the cable-tension adjuster down at the handlebar (clockwise when viewed from the cable), then turn it back one turn. This puts the cable in its starting position. If it's a rear derailleur cable, also screw in the cable-tension adjuster at the derailleur.
Check to be sure the cable-housing caps are secure, and that the housing is nestled in the relays at each section. Test the derailleur or brakes to make sure the cable is working. Now cut the cable, leaving about 3 inches.

Use a special cable cutter, or a Dremmel tool, to cut the cable! If you try to cut it with pliers, you may delaminate the cable.

Put on the cable cap. If you don't have a crimping tool, you can use needle-nose pliers to grasp the shaft of the cap and squish it down tightly onto the cable.
This is what happens when you don't use a cable cap. This derailleur cable has frayed badly, so it can't be adjusted at the retaining clip. And it can't be disassembled and cleaned -- it can only be replaced. We sell cables, housing, cable caps, cable guides, and housing receiver caps.

Perform final adjustments of the cable tightness with the barrel adjuster. For derailleur cables see the section on tuning the front or rear derailleur. For brakes, see the brake tuneup section.

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