Road bike maintenance - brakes
Road brake maintenance
Brake cables need to be replaced every two or three years as the inner liners wear.
easy to moderate
Cable cutters, side cutters, 4th hand tool (cable puller)
Set of brake blocks, new cable set
Check your brakes regularly for signs of wear. As a rule, replace the blocks when the grooves have worn away or the wear line is reached. Brake blocks will wear much more rapidly if you ride in hilly or mountainous areas, carry heavy loads or ride in poor weather.
Even if your bike is used entirely on the road, brake blocks can easily collect grit (causing noisy scraping sounds as you brake), which will accelerate wear on the rims. Remove any bits of grit from the brake blocks with a pick or bradawl.
Fitting new brake blocks
With dual pivot calliper brakes (as fitted to most racing bikes) undo the 5mm allen bolt securing each brake block and replace with the new block. Check that the brake blocks are lined up correctly on the braking surface and that any arrows follow the direction of rotation of the wheel. Some brakes have blocks that allow you to adjust their 'toe-in' (angle to the rim) so that the front edge of the brake block touches the rim 1mm or so before the rear edge). This 'toe-in' prevents squealing and vibration.
This 'toe-in' prevents squealing and vibration
If there is a conical washer fit this on the inside of the brake arm and the plain washer on the outside. These conical washers allow you to angle the brake block inwards. Slide a double layer of card (about 1mm) behind the rear edge of the brake block, push the brake block firmly against the rim and then tighten its mounting bolt firmly. Make sure that the brake block sits squarely against the rim and will not touch the tyre, even when it wears. Recentre the brake and repeat for the other block.
Check that your brake levers are tightly attached to the bars by attempting to twist the lever body sideways. If the levers are not in a comfortable position for you, loosen the clamp bolt, reposition them and then re-tighten. The clamp bolt may be inside the brake lever - you may have to remove the cable completely to access it - or it could be hidden under the lever cover, in which case you'll need to fold back the rubber lever cover from the handlebar. Make sure the levers are level by running a straight edge such as a long ruler between the hood tops and checking that this is parallel with the top of the handlebars.
Assuming that your original cables are a perfect length, neither too long nor too short, you can use the old outer cables as a guide to cut the outer cable lengths you need. Ensure that the bends in the outer casing are not too tight but do not make the outer casing too long either. If you intend to have lights on your handlebars, it is worth fitting the new cables around the lamps to ensure that the cable run is long enough and not obstructed by them.
Outer cable sets will normally come with ferrules fitted (caps on the end of the cable to stop them splaying). Buy some extra ones as you may need to shorten the outer or the ones already fitted may not fit the stops on your bike. They are an essential part of any cable system. They should be a snug fit on the outer cable and a reasonably close fit in the stop on the frame, adjuster on the brake arm and in the brake lever itself.
Cable end caps are another essential part of a cable system and normally are included in cable sets. To fit a cable end cap trim off all but about 5cm of inner cable protruding from the cable clamp. Slide it over the end. Hold in place and with your side cutters and gently crimp the cap two or three times.
Use side cutters to cut between the spiral of the outer cable to make as clean a cut as possible. Use a small file to trim the end flat and then a small pointer to open the end of the liner. Finally fit the ferrule before fitting the cable to the bike. When cutting outer casing, remove the inner cable completely. Many a home mechanic has trimmed outer casing only to find that he has cut the inner wire as well, making it too short to use!
Centering the brakes
- With the brake's quick-release lever closed, thread the inner cable through the cable-clamp eye or slot.
- Use a cable puller (or pliers) to take up all excess cable and ensure the cable casing is seated firmly in its guides.
- Release the cable to let the blocks out to about 1mm from the rim.
- Now fully tighten the clamp.
- Pull hard on the brake lever several times to take up the slack and thoroughly seat the cables in place.
- Un-screw the cable adjuster to bring them in to about 2mm from the rim.
- For Shimano dual pivot brakes adjust the small cross-headed screw.
- For Campagnolo brakes there is a 2mm allen screw to one side of the arch that carries the cable adjuster so that both brake blocks sit an equal distance from the rim.
- If these screws do not permit sufficient adjustment, loosen the 5mm fixing allen bolt behind the brake.
- Re-position the brake a little and retighten the 5mm allen nut. Repeat as above for fine adjustment.