Knowing how to fit a bicycle chain is an essential skill for any home mechanic.
Chains are one of the consumable parts of your drivetrain and wear with use over time.
You can slow down drivetrain wear by staying on top of maintenance, such as cleaning your chain regularly and checking it for wear using a chain-checker. If you allow the chain to wear out past its limit, you’ll then likely need to replace your cassette and possibly chainrings.
In this guide, we’ll take you through the process of replacing a chain. The steps below are relevant to road bike and mountain bike groupsets and any differences in procedure between the different platforms are highlighted below.
What you will need:
- Protective gloves
- Chain breaker tool
- Quick link pliers (if your chain uses a quick link)
- Piece of broken spoke or zip tie (optional)
- A new chain
- Chain lubricant (not essential)
How to check chain compatibility
Chains come in different speeds and are often drivetrain-specific.
Make sure to check the new chain is compatible with your drivetrain. Generally, 9-speed chains and under are cross-compatible, with the exception of Campagnolo.
This is also generally the case with 10-speed chains, again with the exception of Campagnolo. It’s important to note 10-speed Shimano chains are road and mountain-bike specific.
There is some wiggle room with 11-speed between Shimano and SRAM road chains, but it’s generally advisable to stick with the manufacturer and the respective road, gravel or mountain bike line.
When it comes to 12- and 13-speed drivetrains, there is almost no cross-compatibility between brands, so it’s best to stick with the manufacturer and groupset genre.
A note on chain breaker tools
The majority of chain tools are compatible with chains up to and including 11-speed. If you’re running a 12- or 13-speed drivetrain, make sure the chain breaker is compatible.
If you’re running a Campagnolo groupset, with the exception of Ekar and its C-Link quick-link variant, you’ll need to use a chain breaker with a peening function.
If you’re running a SRAM eTap AXS road groupset with a Flattop chain design, you’ll also need to check compatibility because the chain width and roller size varies and won’t work with a conventional chain breaker tool. SRAM has a compatibility document on which tools will work.
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How to replace a bicycle chain
Before working on your bike, make sure you’re wearing suitable workshop clothing and nitrile gloves.
Shift the rear derailleur into the smallest cog on the cassette, then release the clutch mechanism on the rear derailleur if it has one.
If your bike uses a front derailleur, make sure you also shift into the big chainring. This will make removing the old chain easier.
Some like to remove the rear wheel before removing the chain. This takes tension off the chain, which will make it easier to remove and install. Note that you’ll need to re-install it so you have the cassette as a reference point for sizing.
How to remove a bike chain
Locate the quick link or joining pin that holds your chain together.
A quick link will have a set of unique interlocking side plates and can also sometimes be a different colour for easier identification.
A joining pin will generally be a different colour to the rest of the rivets. Shimano and some other brands’ joining pins can also be identified by a raised ring around the outside circumference of the pin.
In this example, we’ll be fitting a Shimano HG-7100 12-speed chain onto a full-suspension mountain bike and a road bike.
If your chain uses a quick link, insert a quick link removal plier on either side of the quick link’s pins.
Squeeze the pliers and the link should come undone. This can sometimes require force, particularly on non-reusable quick-links.
If the chain is destined for the bin and you don’t have a suitable removal plier, you can use a chain breaker to drive out one of the rivets, rather than unlocking the quick link.
If your chain uses a joining pin, you’ll need to use a chain breaker tool to remove it.
Using the tool, drive out one of the rivets.
Make sure you hold the chain and tool straight to avoid driving the pin out at an angle and causing damage to the tool.
With the quick link or joining pin now removed, you can carefully remove the chain, either pedalling it so it comes off the chainring or feeding it through the rear derailleur.
You may want to use a cloth or rag to protect the driveside chainstay and stop the chain from slapping on it as it’s removed.
How to size a new bike chain
Now the old chain has been removed, it can be discarded.
Most quality bicycle workshops will have a metal bin so your chain can be recycled. You could take it to your local workshop to be kinder to the environment.
New chains typically ship longer than required and need to be cut to size to suit your bike and drivetrain combination. There can be some exceptions, such as tandems or high-pivot mountain bikes, which require multiple chains.
Some users like to use the old chain as a reference point to cut the new chain to length.
This method is perfectly valid, but it assumes the worn chain was originally cut to the correct length.
If you know this to be the case and you are not changing your cassette or crankset to a different size, you could use this method.
Alternatively, before removing the chain, you could check it’s the correct length using the methods below.
Rather than put the old and new chain together side by side, it’s best to match the number of outer and inner links together, bearing in mind the old chain will have elongated through wear. This can easily add up to a full chain link’s length, or more.
It is important the chain is the correct length so that it can operate in any gear.
If it is too long, the chain will sag in the smallest gears and could cause damage. If it’s too short, it will put strain on the rear derailleur and hanger, potentially ripping both of the components off the frame.
When installing a chain, check to see if it’s directional. There may be writing on one side of the chain, or there might be an arrow indicating the chain’s direction of travel.
There are different ways of sizing a chain, and we’ll go through some of the most common methods here.
Remember, if you’re using a quick link, you will need to have inner links at either end of the chain.
If your chain connects via a joining pin, the chain will need to have an inner link at one end and an outer link at the other. A joining pin chain should also be routed with the outer link leading towards the crankset from the cassette.
The sizing of Campagnolo 12-speed groupsets also differs. This is explained below.
A note on full-suspension mountain bikes
For full-suspension mountain bikes, you will need to check the length of chain needed doesn’t change as your suspension is compressed. For this, measure the distance from the centre of the crank to the centre of the rear axle.
Now release the air (or remove the spring) from the rear shock and take this measurement again. Size the chain in relation to the longest of these two measurements.
Sizing a chain using the ‘small-small’ method
For 2x and 3x drivetrains, the most accurate method of sizing a chain is to fit the new chain on the smallest cog of the cassette and smallest chainring.
Though you would never ride in this gear, it is the most accurate because it calculates the longest possible length the chain can be.
If you are running an electronic groupset, you may find you’re restricted from putting the chain into this gear – if so, use the ‘big-big’ method, which is explained below.
The chain will need to be routed correctly through the rear derailleur, making sure it passes through both pulley wheels. Take note of any tabs in the derailleur cage and make sure the chain is on the correct side of them.
With the chain in place, pull the two ends towards each other until the derailleur cage starts to move. At this point, you know the cage is tensioning the chain, so it won’t sag or rub on either the pulley wheels or itself where it’s routed over the upper pulley.
With the length determined, you can then cut the chain at the point where the links overlap.
If you are using a quick link and the point at which the chain overlaps doesn’t match (ie, if it overlaps an outer link), move onto the next available inner link and cut there.
This is also the case for a joining pin, where you need to match the outer link with an inner.
You can partially install the quick link (without clicking it into place) or feed the joining pin through the rivet, but don’t push it in to check it is the correct length. You could also test the length by manually shifting into the big chainring and largest cassette cog to confirm it will work in this gear.
Sizing a chain using the ‘big-big’ method
This method entails wrapping the uncut chain around the largest cassette tooth and largest chainring, making sure to bypass the derailleurs.
Pull the two ends of the chain together tightly and add four additional links. If the link you need to cut is an outer link and you will be using a quick link, cut the chain at the next available rivet – this is also the case if you are using a joining pin.
You can mark the point where you need to cut the chain using a whiteboard marker.
Using a chain breaker, cut the chain to the correct length.
Then, install the chain properly, making sure it takes the correct route through the derailleurs.
Campagnolo chain sizing
Campagnolo’s suggested method for chain sizing differs across each of its groupsets.
For chains 11-speed and under, Campagnolo recommends the ‘small-small’ method, but says the distance between the chain when it is under the top pulley wheel should be between 8 and 15mm.
You can use an 8mm hex key as a reference point to check if it at least fits in the gap.
For its 12-speed chains, the Italian brand dictates chain sizing by your bike’s chainstay length, regardless of your cassette or chainring ratios.
Take a tape measure from the centre of your crankset and measure to the centre of the rear dropout.
If your chainstay length is between 405 and 415mm, the chain length should be 110 links. If it’s over 415mm, the chain length should be 112 links.
For Campagnolo Ekar, the brand recommends the ‘big-big’ method.
How to join a new chain using a quick link or joining pin
For chains that use a joining pin, you may want to apply some chain lubricant to the joining pin, prior to installation.
The joining pin installs into the chain from the inside face of the chain towards you.
When the pilot of the pin is broken off at the end, it can leave a small burr and installing the pin in this direction avoids the burr contacting the inside of the cassette teeth, where it could create additional noise.
Take the two ends of the chain and insert the pin between them.
If you’re finding it difficult to join both ends of the chain together due to the tension of the rear derailleur, you can either hold the derailleur cage down with one hand, or use a bent spoke or zip tie.
Use the chain tool to drive the pin in, being careful to stop once it is seated. There will be two points of resistance and you want to make sure the depth is matched with the neighbouring rivets.
When the pin is in place, you can snap off the end with pliers. Many chain breakers have this function built into the tool.
If you’re installing a Campagnolo joining pin, it requires peening once installed. You’ll need to make sure your chain tool is compatible.
For chains featuring a quick link, take the two ends of the chain and insert the connector links by hand. You can now snap the plates together and the chain will be joined.
Quick link pliers can be used for this, but another way is to pedal the master link through until it is sitting above the chainstay.
Pull the rear brake on and pedal downward. You should hear a loud click, signalling it’s seated in place. It’s worth a final visual check too.
Once the chain is connected, you should run your bike through a full range of gears to make sure it’s working correctly.
