Service A Cup and Cone Bottom Bracket

Introduction

Some bottom brackets can be serviced. Others are fit-and-forget, when they wear out the whole unit must be replaced. Some have cartridge bearings that can be replaced. Identify an serviceable bearing by the lock-ring on the left-side cup

Step 1

<h3>Step 1</h3><p>See how to remove the cranks from the cup and cone bottom bracket here
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Remove The Cranks

See how to remove the cranks from the cup and cone bottom bracket here

Step 2

<h3>Step 2</h3><p>If the bearing is serviceable the left-hand cup will have a lock-ring around the outside. Turn this anti-clockwise to unlock the cup. This is easiest with a lock-ring spanner that fits the notches on the ring exactly, you can also use a universal tool with one tooth or a tap it round with a hammer and an old screwdriver. Remove the lock-ring.
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Unlock the cup and cone bottom bracket

If the bearing is serviceable the left-hand cup will have a lock-ring around the outside. Turn this anti-clockwise to unlock the cup. This is easiest with a lock-ring spanner that fits the notches on the ring exactly, you can also use a universal tool with one tooth or a tap it round with a hammer and an old screwdriver. Remove the lock-ring.

Step 3

<h3>Step 3</h3><p>Once the lock-ring as moved back the cup can move. If the cup and cone bottom bracket has hexagonal flats turn it with a spanner. If it has holes use a peg spanner.
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Tools

Once the lock-ring as moved back the cup can move. If the cup and cone bottom bracket has hexagonal flats turn it with a spanner. If it has holes use a peg spanner.

Step 4

<h3>Step 4</h3><p>Turn the left cup – the adjustable cup – anti-clockwise.
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Loosen The Left Side

Turn the left cup – the adjustable cup – anti-clockwise.

Step 5

<h3>Step 5</h3><p>Remove the left cup, collect the balls from the left side, they may be loose or in a clip. Pull out the axle and note which way it fits it may not be symmetrical, one side may be longer than the other. Remove the balls from the other side.
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Dismantle The Bearing

Remove the left cup, collect the balls from the left side, they may be loose or in a clip. Pull out the axle and note which way it fits it may not be symmetrical, one side may be longer than the other. Remove the balls from the other side.

Pro Tip

Use a light to inspect the inside of the right cup. If the bearing surfaces are in good condition there’s no need to remove the right cup, the fixed cup.

Step 6

<h3>Step 6</h3><p>On most bikes the right cup – the fixed cup – is screwed in on a left-hand thread. The exceptions are some old Italian and French bikes. The fixed cup may have two shallow flats or be hexagonal. There’s a bike-shop tool that locks a socket onto the fixed cup to turn it, and various spanners that fit fixed cups. As a last resort you may need to partially strip the frame, clamp the cup in a vice and twist the whole frame.
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Remove The Right Cup If Necessary.

On most bikes the right cup – the fixed cup – is screwed in on a left-hand thread. The exceptions are some old Italian and French bikes. The fixed cup may have two shallow flats or be hexagonal. There’s a bike-shop tool that locks a socket onto the fixed cup to turn it, and various spanners that fit fixed cups. As a last resort you may need to partially strip the frame, clamp the cup in a vice and twist the whole frame.

Step 7

<h3>Step 7</h3><p>Remove the old balls and replace with a set of exactly the same size, they are usually 1/4 inch. It’s better to use loose balls as you can fit more in, than if they’re in a clip. Usually loose is 11 each side, there are usually 9 in a clip. More balls means each one carries a lighter load. Clean the axle and cups with degreaser.
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Replace The Balls and clean parts

Remove the old balls and replace with a set of exactly the same size, they are usually 1/4 inch. It’s better to use loose balls as you can fit more in, than if they’re in a clip. Usually loose is 11 each side, there are usually 9 in a clip. More balls means each one carries a lighter load. Clean the axle and cups with degreaser.

Step 8

<h3>Step 8</h3><p>Check the components on the cup and cone bottom bracket for wear and pitting. If you need to replace the bearing with a new one the most important issue is the length of the axle.
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New Parts?

Check the components on the cup and cone bottom bracket for wear and pitting. If you need to replace the bearing with a new one the most important issue is the length of the axle.

Step 9

<h3>Step 9</h3><p>Pack the left cup with grease and press the balls into the grease.
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Reassemble the cup and cone bottom bracket

Pack the left cup with grease and press the balls into the grease.

Step 10

<h3>Step 10</h3><p>Grease the threads on the frame with anti-seize assembly grease, unless the right cup is on a standard – right-hand – thread in which case clean its frame threads, and the outside of the right cup with acetone, let it dry and apply thread-lock adhesive. Right cups on a standard thread tend to unscrew in use.
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Grease The Cup Threads

Grease the threads on the frame with anti-seize assembly grease, unless the right cup is on a standard – right-hand – thread in which case clean its frame threads, and the outside of the right cup with acetone, let it dry and apply thread-lock adhesive. Right cups on a standard thread tend to unscrew in use.

Step 11

<h3>Step 11</h3><p>If the fixed cup is out pack it with grease and press the balls into the grease then screw it in on the right-side, it usually goes in on a left-hand thread.
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If the fixed cup is out pack it with grease and press the balls into the grease then screw it in on the right-side, it usually goes in on a left-hand thread.

Step 12

<h3>Step 12</h3><p>If the fixed cup is in the frame put a sausage of grease around the right race on the axle and press the balls into the grease. Feed the axle into the frame taking care not to disturb the balls. Make sure the axle goes in the correct way round. The longer arm – it there is one – usually goes on the right, any writing on the axle usually reads from left to right.
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If the fixed cup is in the frame put a sausage of grease around the right race on the axle and press the balls into the grease. Feed the axle into the frame taking care not to disturb the balls. Make sure the axle goes in the correct way round. The longer arm – it there is one – usually goes on the right, any writing on the axle usually reads from left to right.

Step 13

<h3>Step 13</h3><p>Screw the left cup into the frame.
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Left cup

Screw the left cup into the frame.

Step 14

<h3>Step 14</h3><p>Fit the lockring loosely.
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Lockring

Fit the lockring loosely.

Step 15

<h3>Step 15</h3><p>Fit the right-hand crank to help test the bearing on the cup and cone bottom bracket.
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Fit right hand crank

Fit the right-hand crank to help test the bearing on the cup and cone bottom bracket.

Step 16

<h3>Step 16</h3><p>Adjust accordingly and then tighten the lockring to fix into position. Replace the left hand crank.
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Finish

Adjust accordingly and then tighten the lockring to fix into position. Replace the left hand crank.