How To Check a Chain for Wear and Why it’s Important

checking your chain for wear

Checking your chain for wear is one of the easiest maintenance tasks to do on your bike but also one of the most important!

As you will find out from reading this article, ignoring this simple check can be very costly!

In this article we’ll explain what chain wear is, how it occurs, how to measure it and the consequences of not monitoring it.

What Is Chain Wear?

Chain wear is also known as chain stretch because when a chain wears the length of the chain increases, or stretches. 

It is the wearing down of the individual parts of the chain which causes this stretch. 

A chain is considered to be stretched and requires replacing when it gets to a certain point which is measured in percentage, this percentage is different for different sized chains. 

On chains designed for 10 or fewer gears you should change the chain at 0.75%.

On chains designed for 11 or 12 speed, you should change the chain at 0.5% wear.

On chains designed for single speed, replace the chain at 1% wear.


Why You Should Check Your Chain For Wear?

A chain that isn’t monitored and left to stretch can have a huge effect on your bike, from slipping gearing, excessive wear of other parts, to the chain snapping mid-ride!

As well as a chain wearing and stretching in length, a chain can also wear and create play sidewards. This sidewards play is caused by the rollers wearing. This form of wear is what can cause poor shifting up and down the cassette as the chain is not aligned perfectly, this would require more sideward movement to derail the chain off the sprocket its on. 

A worn chain can also be very costly and reduce the life of other parts on your bike, the cassette and the chainrings. 

A worn chain wears the sprockets of a cassette and the chainrings because the pitch of the chain is now longer, which in turn stops the roller of the chain sitting in the bottom of the teeth. The chain will now start to climb and ride up the side of the teeth and over time this will wear the teeth down, creating a spiky tooth with an elongated profile, like the middle chainring below.

The cost of replacing a cassette and set chainrings every time your chain stretches should be enough of a reason to check your chain for wear!

worn teeth on chainring

How To Measure Chain Wear?

The best and most accurate way to check a chain for wear is to use specific chain checker tools. 

The chain checker tool that we recommend and use in our videos in the app (iOS and Android) is the Park Tool CC-2. This is because it has a slide scale which visually indicates the wear in the chain. This tool can also be used on all chains. Just watch out because this particular tool can be hard to get hold of since the pandemic caused a shortage in cycling tools.

The second way of checking chain wear is to use a Park Tool CC-3.2 tool or similar. This tool is two sided with one side showing 0.5% wear and the other showing 0.75% wear. With one end of the tool hooked against a roller, if the other end of the tool fits into the link the chain is that amount stretched (0.5% or 0.75%).

Click on the links below to learn more about the bicycle maintenance guide app