How to replace a bike chain

If your chain is worn out, here's how to swap it for a new one

Clock11:00, Sunday 18th June 2023

Tools Needed

Check your chain's worn out before you replace it

Step 1

Check your chain for wear

Chances are, you'll be replacing your chain because it's worn out. To check how worn your chain is, use a chain checker. These devices show the extent to which your chain has 'stretched', or become elongated because of wear in the pins.

On 11, 12 or 13-speed bikes, you should replace your chain when it's 0.75% stretched.

Watch: How To Check For & Measure Chain Wear

Change into the smallest cogs to reduce the chain tension

Step 2

Change into the small chainring and sprocket

Put your bike in a work stand, if you've got one, and change into the smallest chainring and the smallest cog on the cassette. This will reduce the chain tension, making it easier to manage and remove the chain.

Look to see if your chain has a quick link like this

Step 3A

Find the quick link

Spin your chain slowly, watching as you go for a quick link or 'master link'. Not all chains will have one.

Chain link pliers make this job very easy

Step 3B

Open the quick link

If you have a quick link on your chain, open it up by squeezing the links together. You can use needle-nose pliers for this, but it's far easier with bike-specific chain link pliers.

The joining pin is trickier to find

Step 4A

Find the joining pin

If your chain doesn't have a quick link, you'll need to take it off using a chain breaker tool. If your old chain is going in the bin, it doesn't matter which link you break, but if you want to reuse the chain, find the joining pin. It looks slightly different to the other links, as you can see.

Use a chain breaker tool to remove the chain pin

Step 4B

Remove the chain pin

Use a chain breaker tool to push the pin out of the chain. To do this, position the link in the chain breaker and screw down the pin, making sure it's dead straight – the pins on chain breaker tools can snap if they're pushed in at an angle.

Make note of the route the chain takes through the rear derailleur

Step 5

Remove the chain

Remove the old chain. As you do so, pay attention to the route the chain takes through the rear derailleur, so you can put the new one in correctly.

Lay the two chains next to each other

Step 6

Measure the old chain against the new one

To match the length of the new chain with the old one, lay them side by side and use the chain tool to align their lengths. The chain length should be short enough that there is no slack in the chain when in the smallest front chainring and smallest rear cog, yet long enough so that the rear derailleur isn't overly stretched in the largest gear combination.

Watch: Why chain length matters and how to get it right

Use a chain breaker to shorten the new chain

Step 7

Shorten the new chain

Once you've measured your new chain against your old one, you can shorten the new chain accordingly. Make a note of which link needs removing then press it out using the chain breaker.

If you're using a quick link, bear in mind that the quick link needs to attach to two inner chain links, and that the quick link adds half a link to the chain's overall length.

Make sure the chain goes the right way through the rear mech

Step 8

Thread the new chain through your drivetrain

Chains are directional, so make sure that the side of the chain with text printed on it is facing outwards from the bike.

Then, route the chain through the pulley wheels, cassette, and chainrings, ensuring it follows the correct path. Position the two ends of the chain together on the lower run.

Chain link pliers come in handy again for this step

Step 9

Join the quick link

If you're using a quick link, make sure the arrows on it are installed in the direction of travel when pedalling. Position pliers around the quick link and pull them open to click the link together.

Push the pin in from left to right

Step 10A

Alternatively, push in the chain pin

If using a joining pin, place the chain tool through a gap in the spokes and align it with the joining pin. Slowly turn the tool's handle to push the pin from inside to outside, until it's flush with the inner surface of the chain links.

Break off the end with a pair of pliers

Step 10B

Snap off the end and free up the link

Remove the tool and snap off the excess from the chain pin. The link with the chain pin will be a little stiff at first, so flex it in your hand to free it up.

Check your gears are working

Step 11

Check your gears

Run through all the gears to ensure smooth shifting. Test the chain on the little chainring, big chainring, and various cogs on the cassette. Make any necessary adjustments to ensure proper functionality.

If your gears are working well, you're done. Just make sure to keep the chain clean and lubricated over the coming weeks and months.

Jargon Buster

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