45. How To Replace an Inner Brake Cable

Remove the old inner brake wire and install a new one.

IMPORTANT: Nuts and bolts on your bike should always be tightened to the manufacturer's specifications.
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Brake cable inner wires wear out over time. Other than obvious fraying, rust or visual wear, you can tell your cables are worn when your braking starts to feel sluggish. If lubricating the housings or brake levers doesn’t help, they’ll likely need replacing.

Tools

For this job, you’ll need a replacement brake cable inner wire. Most brake cables have a barrel end that looks like this, unless you have a road bike with drop handlebars, in which case it’ll have a cylindrical mushroom head like this. Often new brake cables will come with each type on both ends. I recommend stainless steel cables if you’re riding regularly in a wet climate, as they won’t rust. You’ll need a good set of wire cutters, some bicycle specific cable cutters if you’ll be replacing the outer cable housing, and some triflow or light lubricant. You’ll need either a 9 or 10mm metric open end wrench or a 5 or 6mm hex key for the brake’s cable pinch bolt. You’ll also need to know how to adjust your brakes and levers, as explained in previous tutorials depending on your type of brake system.

Brake Cable Removal

The first step is to carefully observe how your cable is presently routed from the lever to your brake. A misrouted cable can cause many problems. It may help to photograph each section of the cable from the lever to the brake so you can use it for reference. Your brake may not look like the one pictured here, but the concepts will be the same.

Now disconnect the cable by loosening the brake’s pinch bolt. Notice how the cable is flattened where it was pinched. I like to cut the cable just before this part so it is easier to remove by sliding through the outer cable housings. I recommend replacing the outer cable housings at the same time. See the tutorial titled “How To Replace Cable Housings”.

Brake Cable Installation

Once you have nothing but the brake lever and the cable left, line up the slots in the lever’s barrel adjuster and then pull the cable through and remove the head from the lever. Install the new cable into the lever the same way the old one came out.

Now turn your barrel adjuster clockwise almost all the way, so the barrel slots lock the new cable in place. Drop some light oil into your cable housings and make sure the outer housing’s cable ferrules are firmly in place before carefully sliding the new cable through the housing. Then route your cable the same way it was before and thread the inner cable under the pinch bolt’s washer. Pull the cable tight and tighten the pinch bolt. The cable will flatten when tightened. Always tighten bolts to the manufacturer’s torque specifications. Adjust the brake as needed. Search the other tutorials for your specific type of brakes.

Once installed and adjusted, cut the wire about 2 inches further along the cable. Your new cable should have come with a cable end that can be gently crimped on using wire cutters or pliers. This will prevent fraying. Then give the cable a slight bend and tuck it out of the way behind the brake arm.

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4 Responses to “How To Replace an Inner Brake Cable”

  1. Bill on February 14th, 2010 7:37 pm

    Great job Alex!!!

  2. Skyguy9999 on February 17th, 2010 9:43 pm

    Something I’m wondering from doing many of these, both shifter and brake (now).

    1) There’s been many an occasion where I got dirt or other crud on the cable when I extracted it, which would indicate that it got into the cable housings (like rain/mud). I just shot WD-40 into the cable housing sections until it came out the other side relatively clean. Good idea or not? (I had to take a couple of sections to an air compressor and use an air hose on them, so that says how dirty some got)

    2) Then I wonder why you use the light lubricant in the cable housing? I ask more a “why that choice” question, since I realize from experience that the lubrication is useful. I read all manner of options (from light lubricant to bike chain oil up to greasing the cable lightly) – personally I’ve been using chain oil. But I have to wonder since on many of the cables I’ve replaced I hear grinding when I pass the new cable through – wouldn’t a liquid lubricant dissipate too much to be useful? I guess it doesn’t matter too much, since I haven’t had any problems with any of my cables (yet), but just wondering…

    and

    3) Any ideas on handling brake cable ends (on the brake side) that are tough to get out would be welcome, too. I’ve run into one or two that I had to worry about tearing the brake handle up to get out…

  3. Alex on February 18th, 2010 12:39 pm

    I wouldn’t use WD-40 in the cable housings. It has some lubricating properties, but they won’t last long. Better to use a light lube like triflow on your cable housings. Not sure about the problem you’re having with the cable ends. If you post a photo in help forums we should be able to figure it out.

  4. Corey on February 20th, 2010 12:02 pm

    Awesome job on this, Alex. I love your vids… if I ever get stumped, I go to you site… wicked cool… Thanks!

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How To Replace an Inner Brake Cable
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