However casual you are about bike maintenance, you need to make sure that your brakes are working properly every time you set off on a ride. This doesn’t need to be a lengthy procedure – just give your bike a careful visual check before you head off.
The steps below make up a quick and regular check to keep your brakes in good running order and they give you warning when it’s time for a more serious overhaul. Each of the steps below includes relevant page numbers, so that if any of the checks show a problem with your braking system, you can sort it out straight away. Whatever you do, don’t set off on a ride with brakes that don’t work properly.
Lift each wheel and spin it, to check the brakes don’t rub on the rims or the tyre as the wheel turns. Look at the gap between the brake block and the rim on each side of each brake.
You’ll need to disconnect the brake cable so that you can pull the brake blocks out from the rim. V-brakes are designed to make this easy. They also help when you want to remove and replace the wheels because you can get the tyre out past the brake blocks without letting the air out.
The brake cable
The brake cable arrives at the brake unit via a short curved metal tube called a ’noodle’ or ’lead pipe’ (pronounced as in ’leading in the right direction’, not ’lead, the heavy metal’). The end of the lead pipe has a pointed head with a raised collar. The brake cable passes through the noodle and then clamps onto one of the brake units. The other brake unit has a hinged hanger with a key-shaped hole for the noodle. The collar stops the noodle pulling through the hanger, so when you pull on the cable, the two brake units are drawn together, pulling the brake blocks onto the rim. The section of cable between the hanger and the cable clamp bolt is often concealed inside a black rubber boot that helps keep the cable clean.
To release the brake units, draw back the rubber boot to reveal the head of the noodle where it emerges from the hanger. Squeeze the two brake units together to create slack in the cable. Pull the noodle back and out of the key-shaped hole, then pull up to release the cable from the slot in the key-shaped hole. Let go of the brake units – they will spring right back from the rim.
To reconnect the brakes, squeeze the brake units firmly onto the rim. Pull back the rubber boot so that it’s out of the way of the noodle, and guide the head of the noodle into the hole in the hanger. Make sure it’s seated securely: the raised collar must be butted firmly up against the hanger. Refit the rubber boot back over the head of the noodle. Pull the brake lever to confirm that everything is seated correctly.
Step 1 : Inspect the condition of the pads. Release the brakes (see above), pull each side away from the rim, and check that each braking surface is flat, has nothing stuck in it and isn’t worn through. If they’re worn. Otherwise, reconnect the brakes, checking that the brake noodle is
firmly and securely located in its hanger.
Step 2 : Check that each block hits the rim flat, square and level. Brake blocks that are too high will cut through the tyre, causing explosive punctures. Blocks that are too low hang under the rim, wasting brake potential and creating a lip that eventually starts to snag on the rim.
Step 3 : Run your hand along each cable, from lever to brake unit, checking for corrosion, kinks, fraying or damage to the casing (A). Pull the lever firmly towards the bars and check that each brake locks the wheel when the lever is halfway to the bars.
Source : BIKE MAINTENANCE TIPS, TRICKS & TECHNIQUES