Removing the Old Cable
Snip the crimped end off of the inner cable. Find the end of the brake cable that sticks out of the retention clamp on the braking mechanism. This is the wheel-end of the cable, as opposed to the end that attaches to the lever. Use a pair of wire cutters to snip off the crimp on the end. It’ll be easier to slide the old cable out of its housing if you snip off the crimped end. Otherwise, it’ll might get caught inside of the housing. Your new cable should come with a new end crimp. If it doesn’t, cable end crimps are inexpensive and available at bike shops.
Loosen the pinch bolt with a 5 mm Allen key. Locate the pinch bolt that secures the cable to the retention clamp. It has a small 6-sided indentation that fits a 5 mm Allen key. Insert the Allen key into the indentation, twist it counterclockwise to loosen the bolt, then slide out the brake cable. The brake cable’s housing might have ferrules or end caps that secure it to the frame, lever, or retention clamp. Be sure to safely store these and any small parts to avoid losing them.
Turn the barrel adjuster at the handlebar. Find the adjuster, which is a small barrel next to the brake lever on the handlebar that secures the cable to the lever. The adjuster and lever each have slots, or thin openings that look like straight lines. Using your fingers, rotate the adjuster counterclockwise until its slot lines up with the one in the lever. For a straight-handled bike, the brake cable runs through the adjuster, and a nipple at the end of the cable slides into the brake lever. In a road bike with curved handlebars, the cable threads directly into a clamp within the lever, so skip this step if you don’t have an adjuster.
Slide the cable out from the brake lever. For straight handlebars, pull the brake lever, then slide the cable through the slots in the adjuster and lever. The rounded end of the cable, or nipple, fits into a slot within the lever. Keep pulling the lever as you slide the nipple out of the slot to finish detaching the cable. For curved handlebars, pull the brake lever, then find where the cable threads into a clamp within the lever mechanism. For some models, you can just pull the cable out of the clamp when the lever is engaged. For other models, you might need to engage the lever several times to detach or attach the cable, or you might have to remove a cable cover to access the clamp. Consult a bike repair manual or search online for your bike model’s specific method.
Remove the outer cable housing, if you’re replacing it. Slide the housing out from the slots that hook it to the bike’s frame. If the cable housing is attached to your frame with zip ties, cut and discard them. Check the ends of the housing for plastic or metal ferrules, or end caps, that secure it to the bike’s lever and anchor. You might not need to replace the housing if it's in good shape. However, you’ll definitely need to replace it if it’s worn, stiff, rusty, packed with dirt, or has any kinks. For rear wheel brakes, a section of housing runs from the handlebars, and another runs from the wheel. The section that runs from the wheel gets dirty more easily, and you might only need to replace this section. It’s wise to take pictures of how the cable housing is threaded around your bike’s frame before removing it. That way, you’ll have a reference just in case you forget. For a road bike with curved handlebars, you might need to take off the grip tape to remove the cable housing. Peel off the tape, if necessary, then re-tape the handlebars when you attach the new housing.
Slide the inner cable out of the housing, if you’re not replacing it. If you’re leaving any sections of cable housing in place, grab an end of inner cable and gently slide it out of the housing. If the cable has a nipple, pull it out from this end, as the nipple won’t fit through the casing. If there are 2 sections of cable housing, try snipping the exposed inner cable that runs between the sections. It’s easier to pull shorter lengths of cable through each section of housing than it is to slide out the enter cable.
Installing the New Cable
Make sure your new cable matches the old one. Different brake cables are specifically designed for straight handlebars and drop handlebars. Double check that your new cable is made for your bike. Be sure any nipples or end caps on the new cable match the old one. To ensure that you get the correct replacement, take the old cable to a bike shop and ask an employee there to help you find a match. If you’re replacing the cable housing, be sure that the housing is labelled for brakes. Shift cable housing isn’t as strong and could buckle.
Cut your new cable housing to match the old one. If you’re replacing the cable housing, hold the new casing against the old one. Measure accurately; if the new housing is too long, the inner cable will be exposed to too much friction. Use a bicycle-specific cable-cutting tool or high-quality wire cutters to cut the new casing as cleanly as possible. Use caution when using wire cutters or any other sharp tools. If your bike has rear wheel brakes and 2 sections of housing, cut your new housing to match both sections. After cutting the new cable housing, inspect the cut ends. If the cuts aren’t clean and square, remove any rough edges with a metal nail file.
Install the new cable housing, if you’re replacing it. If there were any ferrules or end caps attached to the old housing, slide them onto the ends of the new one. Hook the new housing into the slots that secure it to the frame. If applicable, make sure the ferrule that fits into the handlebars and the one that fits into the retention bolt are in the right places. If there are any ferrules, don’t slide them into the lever, adjuster, or retention clamp yet. You still need to slide the inner cable through the housing. The brake cable will not work properly if the housing bends sharply. Ensure any spots where the housing curves around the handlebars and down the frame are smooth and gentle. If necessary, secure the housing to the frame with small zip ties. After pulling them tightly, cut the excess lengths off of the zip ties for a cleaner look.
Thread the cable through the outer housing. Carefully slide the cable through the entire length of the outer casing. If you have a rear wheel brake and 2 sections of casing, start by threading the section that runs from the handlebars. Make sure the end of the cable that attaches to the brake lever is at the right end of the bike. The end of the cable that slides into the retention clamp at the brake mechanism should be just plain, bare wire. If an end of the cable has a nipple, make sure it’s positioned near the handlebars. For a bike with a rear wheel brake, slide the remaining length of the cable through the second section after threading the first. Before threading the second section, you can slide rubber donuts over the inner cable. They’re available online and at bike shops, and will prevent the exposed metal cable from rubbing against the frame and messing up your paint job.
Slide the inner cable into the brake lever. For straight handlebars, pull the brake lever, then hook the nipple into the rounded gap within the lever. Ensure the adjuster slot is still aligned with the lever slot, then slide the cable into the slots. With the cable in place, disengage the brake lever and twist the adjuster clockwise to secure the cable. For drop handlebars, engage the brake lever, find the clamp or eyelet inside, then thread the end of the cable through the mechanism. Check the manufacturer’s instructions for your model’s specific threading method and, if necessary, replace the cable cover.
Secure the cable to the retention clamp. The retention clamp, or anchor, is where the other cable end attaches to the brake mechanism. Turn the pinch bolt counterclockwise with the Allen key, loosen it, pinch the brake pads so they touch the wheel, then slide the cable through the retention clamp. Pull the cable tightly, replace the pinch bolt, and turn the bolt clockwise with the Allen key to tighten it. While optional, a fourth hand tool makes it easier to tighten the bolt. Grasp the end of the cable with the tool’s opening, then squeeze the handles to tighten the cable as you turn the pinch bolt clockwise with the Allen wrench.
Slide the ferrules at the ends of the cable housing into place. After securing the ends of the inner cable, slide the outer housing’s ferrules or end pieces over the barrel adjuster and retention anchor. The exact method of fitting the housing into the frame vary by model, so check a bicycle repair manual if you’re not sure. If you don’t have a repair manual handy, find your bike’s model number and search for the manual online. Most manufacturers publish instruction manuals on their websites. If you removed the grip tape from drop handlebars, re-tape them. Tape over the new cable and housing so they're in the same position as the old set. Purchase new grip tape online or at your local bike shop.
Completing the Installation
Pull the lever to check the cable resistance and brake mechanism. After securing the inner cable and outer housing, engage the brake lever to check your work. Pull the lever 5 to 10 times, and see if you encounter your preferred level of resistance. As you pull, check the brake pads and make sure they come into contact with the wheel. If the lever is too tight, loosen the barrel adjuster at the lever or unfasten the pinch bolt to give the cable more slack. If the lever feels loose, tighten the barrel adjuster. If it’s still too loose, unfasten the pinch bolt, pull the cable tighter with a pair of needle nose pliers or the fourth hand tool, then tighten the pinch bolt. For the most accurate method of adjusting the tension, use a fourth hand tool and torque wrench to tighten the cable to 6 Nm or to the manufacturer’s specifications.
Trim excess cable, then crimp the end. After adjusting the tension, use your wire cutters to snip the end of the cable. Slide a cable end cap over the trimmed end to prevent fraying, then squash it into place with pliers. Some bike mechanics recommend leaving about 3 inches (7.6 cm) of cable exposed from the brake clamp so there’s enough length for future adjustments. However, there’s a risk that this length could get caught in the wheel or brake mechanism. If you choose to keep the end long, hook the extra cable securely around the brake, and be sure it doesn’t obstruct the wheel or brake pads. Alternatively, just trim the excess wire to about ⁄4 inch (1.9 cm).
Do a final check by rocking your bike with the brake engaged. Double check that your brakes work properly before you go riding. Walk the bike forward, then pull the brake lever, and make sure the braking wheel has stopped. Rock the bike forward a bit to make sure the brake doesn’t budge. If you have trouble, ensure the cable's connections to the lever and retention anchor are stable. Double check that engaging the lever causes the brake pads to close around the wheel. If you can't find the problem, consult a bike mechanic.
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