Chains will wear and ‘stretch’ over time, especially if not lubricated regularly. This can wear down the chainrings and cogsets leading to chain slippage, poor performance and possible accidents. In the next of our series on Cycling Expert Advice, Made Easy, we look at how to replace a worn chain.

Checking the Chain for Wear

Wear on the chain is caused by dirt getting into its joints, combined with the constant friction of contact with the sprockets. A chain wear indicator tool can be bought for less than £10, but you can simply use a ruler instead. Each chain link is made exactly half an inch long, so 12 inches from the centre of a link pin should be the centre of the 24th pin along. If the chain is longer by more than 1⁄16 inch, then it is time to replace it.

Replacing a Worn Chain

Check to see if the chain has a quick-release link (also called a snap link), which is a special type of link that can be fitted and removed without a chain tool. It looks different to the other links. If it does, you can pop it off by hand or with a screwdriver or other tool.

Failing that, you will need to use a chain tool as follows:

1. Place the bicycle on your work stand or lean it against a wall.

2. Hook a short piece of electrical wire around the links on either side and over the link you are going to break. This will prevent the chain clattering onto the floor and the derailleur kicking up.

3. Turn the screw handle of the chain tool anticlockwise until it stops. This will retract the chain tool’s pin so that you can fit the chain into the tool and align the chain tool pin with a chain link pin.

4. Fit the chain tool around a link of chain that you are going to break. There are two slots for this on the chain tool. Use the one furthest from the chain tool handle. Using the nearest slot is for loosening only.

5. Screw the handle clockwise until the chain tool’s pin touches the chain link pin. Make sure it is aligned and then continue to turn clockwise. There will be resistance but keep going until the pin is pushed out.

   • If you are removing the chain to clean it and intend to put it back on again, push the link pin a little over half way through and retract the chain tool pin and remove the chain tool. Then take the chain in your hand and twist it a few times; it will come apart with the link pin still fitted in the outer link plate. This will make it easier to reattach by using your chain tool again to push the pin back through the plates.

6. Your new chain will probably have more links than your old chain so these need to be removed using the chain tool. Before breaking the new chain, make sure you are clear about how the ends fit together. If you are using a pin you need an outer link on one end and an inner link on the other so that you can slot the inner link inside the outer and push the pin through with the chain tool. If you have a quick link (snap link), you need two inner links at either end of the chain as the quick link is an outer.

7. Place the new chain over the bottom bracket, inside the chainrings, and over the small sprocket at the rear. Align the derailleur and feed the chain over the upper pulley, down and behind and under the lower pulley. Use your electrical wire to link the two ends together.

8. Align the chain ends and, using the chain tool, screw the pin until it sits neatly through all four plates. Don’t forget to remove the electrical wire.

9. The new join will be a little stiff, so work the link up and down and side to side a little, then lift the chain off the bracket and feed it onto the lowest chainring from underneath whilst pedalling backwards with your hand.

10. Lubricate the chain and wipe off any excess.

This post is based on an extract from our bestselling book, Cycling by David North (ISBN: 9780857750969) – where you can find more on the above and further help and advice on Cycling.

Links

• Check out an interactive map of Britain's best bike rides here.

• Check out top ten tips to help you winter-proof your bike here.

• If you want to know more tips and advice on choosing, riding and maintaining a bike, why not buy our Cycling book? Take a look here.