Knowledge Level: Intermediate
Although our main focus as cyclists is usually how we can ride faster, being able to slow down and stop is equally important. Whether you’re tackling a long descent in a sportive, braking hard into a corner in a criterium race or approaching a junction on your commute, having reliable brakes is essential for safe, successful and enjoyable cycling. Follow this advice from the Great Britain Cycling Team mechanics on how to ensure your brakes are functioning properly and won’t let you down when it matters.
The different types of brakes and how they work
Fitted to the majority of road bikes, calipers have two opposing brake blocks/pads acting directly onto the wheel rim as the brake lever is pressed.
Found mainly on cyclo-cross and older mountain bikes. These work in a similar way to the calliper brake, in that they operate on the wheel rim braking surface. The two cantilever arms are linked by a short length of brake cable which is connected in its centre to the cable running to the brake lever.
Disc brakes are mainly used for mountain biking but are also becoming increasingly common on cyclo-cross bikes, tourers and even high end road bikes. There are two different types, mechanical and hydraulic. Mechanical brakes are operated by a cable like caliper and cantilever brakes, whereas hydraulic brakes work with master and slave pistons connected by a hydraulic hose filled with fluid. Both types of brakes squeeze brake pads onto a disc braking surface, the disc being connected to the hub. Braking forces are then transferred through the spokes into the rim/tyre and through to the ground as the brake is operated.
We’ll look at hydraulic brakes in more detail another time, they’re complicated enough to deserve their own feature.
Other types of brakes
Drum type brakes also exist for tandems and for some back-pedal type children’s bike. We won’t go into detail on these here but they follow the same basic principles.
Looking after your brakes
All brakes operate by converting the energy of movement (kinetic energy) through friction between the brake pads and braking surface (rim or disc) into heat which is then dissipated to the air and through the bike itself.
With this in mind it is critically important to keep anything that might interfere with this friction away from brakes and braking surfaces. For example, when spraying lubricants and water dispersants onto the drive chain, it’s all too easy to get some on the rims or discs and severely compromise your brakes and contaminate your brake pads at the same time. It’s worth noting that once contaminated, braking surfaces will need cleaning with a degreaser and/or brake cleaner and brake pads will very likely have to be discarded.
Getting it right
For all braking systems you need to ensure that the wheel is free to rotate without contacting the brake pads. You also need to ensure that the brake levers are appropriately positioned on the handlebars and the reach adjustment (if available) is set so that the levers fall to hand and do not contact the ‘bar under a maximum load squeeze.
Caliper, cantilever and mechanical disc brakes are (nearly) all connected by a cable with an inner steel core (cable) and a 5 mm diameter ‘outer ‘comprising a wound steel flexible helix (which resists compression) with a PVC coating. They should also have some means of adjustment at one or both ends. This is usually a screw and locknut arrangement which lengthens or shortens the outer and hence adjusts the pad-to-brake surface distance.
With all the friction and consequent heat your brakes develop, they will require some looking after and the blocks or pads will require periodic replacement. For braking systems that work on the wheels’ rims, these will also eventually need replacing and wear should be carefully monitored. There are indentations on most rims that, when no longer visible, indicate that the rim is worn. This can be a fairly pricey replacement but, by maintaining your brakes properly and regularly replacing the pads and blocks when worn, it won’t be required often.
What you’ll need
Either a 5 mm allen key or 8 or 10 mm spanner depending on how your brake cables are secured.
The brake blocks or pads will probably have a retaining clip or Allen screw, a 2mm Allen key should fit.
Cable crimper and crimps
Pliers (to hold the cable taut – only use them to cut cables if you have nothing else as they use a crushing action)
Once you have all the required tools and components, remove the wheels as this makes the job far easier.
1. Make sure the pads or blocks are not worn beyond their limits. There’s usually a line to denote minimum thickness but use your judgment and replace if in doubt. Get blocks or pads appropriate to your caliper/cantilever and your braking surface. This is usually aluminium but can also be carbon or ceramic depending on the wheels.
2. Ensure the ‘shoes’ holding the pads are oriented in the correct direction so that the pads cannot slide out with forward motion of the bike (closed end facing ‘forward’ – if in doubt ask someone who knows). Also make sure any retaining clips or screws are in place.
3. The pad should make contact with the braking surface of the rim and be aligned with it circumferentially, not overlapping or touching the tyre. As the brakes wear out, the pad contact point may move. With caliper brakes it generally moves outward towards the tyre so make allowance for this when positioning a new pad. This can take a little time to get right until your technique improves. Practice is the key here, so perseverance is important. Secure tight enough that under reasonably firm pressure from your fingers or thumb, the pads cannot rotate.
4. It’s good practice for the caliper to be centred so that the brake pads or blocks touch the brake rim at the same time rather than the brake pushing the rim over. For some caliper brakes you may need to loosen the brake off in the fork or frame to rotate it (usually a 5 mm allen key is required for this).
5. Make sure you tighten it up securely once you have it centred and try the brakes to see that both pads touch the rim at the same time. Some callipers also have an adjuster screw on one arm (3 mm Allen key needed here) which allows one pad to be moved in or out independently of the other.
6. Cantilever brakes have a phillips screw adjuster which alters the spring tension to allow the brakes to return together. Increase tension on the side where you need to move the pad further away from the rim, and this will bring the other pad closer.
7. Ensure the cable runs smoothly and the caliper or cantilevers move freely. If necessary, lubricate the cables, we usually use chain lubricant. You may have to disconnect the cable to get the lubricant to flow along it.
8. If lubrication doesn’t work effectively the cables will need replacing, possibly just the inner cable but I find that it’s better to replace the outer one as well. Make sure you use brake cable inners and outers (rather than ‘gear cables’ which are generally a smaller diameter) and with a nipple to suit your brake levers. Cut the outer length to allow the handlebars to freely rotate in both directions, file off any burrs and use the appropriate 5 mm ferrules on the ends.
9. Thread the inner through as per the original cable and check the nipple is engaged at the lever end and the cable is pulled with movement of the lever. Make sure the tab which opens up the caliper for wheel removal is closed and secure the inner cable at the caliper end with the clamp screw. Tighten the clamp up enough so that even with a strong pull on the lever, the cable does not pull through.
10. Use the cable adjuster for fine tuning of lever pull and leave some adjustment for taking up brake pad wear. If your wheels are out of true you may find it difficult to get reasonable lever travel without the pads catching the rim. If this is the case your wheels will need sorting out by a friendly wheel builder at your local bike shop.
To finish, trim the excess inner cable leaving enough to get hold of should you wish to adjust the length at some future point. Use a cable end crimp to stop it fraying. For cantilever brakes inspect the loops linking the cantilevers and replace if necessary, again ensure everything is properly tightened and secure.
A top tip is when replacing cables is also to replace your bar tape and, while the old bar tape is off, check your gear cables too
Check everything once again and try the operation of the brakes with a firm and a light touch. Everything should work smoothly and return to position when released. Test the operation of the brakes in a traffic free environment before heading out to ride.