Check And Service Brake Blocks

Introduction

Rim brakes slow and stop the bike by pressing soft blocks against the wheel rim to produce friction. A brake block wears away with use.

Pro Tip

Different materials, different compounds are available for different types of rim. Steel rims don’t offer very good braking – with a marked loss of stopping power in the wet. Special brake blocks for steel rims help a little. Softer brake blocks stop you better but wear down faster. A hard brake block will last longer but may accelerate rim wear.

Step 1

<h3>Step 1</h3><p>Open the brakes – remove the wheel if convenient – to examine the faces of the brake block that presses on the rim in braking. Any stones or glass trapped there will damage the rim, remove them. You may also find fragments of aluminium that have come from the rim. Remove them with tweezers.
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Check The Brake Block Faces

Open the brakes – remove the wheel if convenient – to examine the faces of the brake block that presses on the rim in braking. Any stones or glass trapped there will damage the rim, remove them. You may also find fragments of aluminium that have come from the rim. Remove them with tweezers.

Pro Tip

As brake blocks wear the action of the brake changes, some brake blocks – for example’V’ brakes, and one side of a dual-pivot calliper – move away from the tyre. If part of the block starts to miss the rim it won’t wear. The resulting ridge tends to hook the blocks in the ‘ON’ position so they can’t release.

Step 2

<h3>Step 2</h3><p>Take the brake block out of the brake if necessary and carve off any ridge with a knife. File the face smooth. If you take the block off note carefully the position of any washer.
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Trim If Necessary

Take the brake block out of the brake if necessary and carve off any ridge with a knife. File the face smooth. If you take the block off note carefully the position of any washer.

Step 3

<h3>Step 3</h3><p>The blocks may have a wear line. When the wear reaches the line or they start to look thin replace them.
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Replace If Necessary

The blocks may have a wear line. When the wear reaches the line or they start to look thin replace them.

Pro Tip

If the bike is used for high-performance change the brake blocks every couple of years regardless of wear as the rubber gets hard with age and the blocks don’t work so well.