Chain Wear & How We Measure It

Chain Wear & How We Measure It

A worn chain means poor shifting. It will also accelerate the wear of other more expensive components and a worn chain is more likely to fail (snap!).

We often receive customers’ bikes in for servicing and find that the chain is worn. We will recommend they replace a worn chain (and more often than not, the cassette) as part of the service. We are not doing this to squeeze more cash out of our customers. We are doing this because:

  • you can save money by replacing your chain before it is worn to the point that other components will be worn;
  • the chain checker tool we use shows that the chain is worn and we are following the manufacturer’s guidance.

How do we know if your chain is worn?

Most chain manufacturers recommend you replace their chain when the chain reaches 0.5% and 0.75%. Using the Park Tool CC-3.2, we are going to show you how we measure chain wear.

1. Note the two measurements at the end of the chain checker (0.5 and 0.75). These marking represent a % of chain length. First we start with the 0.5% measurement.

2. Install the hook end of the chain
checker inside a chain link (not a quick link) and attempt to
install the other end of the chain checker into the chain.

3. If it doesn’t fit, as is the
case in the picture on the left, your chain is not 0.5% worn. If it
does go in, like in the picture on the right, it tells us that the
chain is at least 0.5% worn. This means your chain is now 0.5%
longer that it was.
If you are running an 11 or 12 speed chain
you should replace your chain now

4. Switch to the other side of the
chain checker to check for 0.75% wear. If it does not go in (as in
the picture on the left), we know it is not 0.75% worn.
If you
are running an 11 or 12 speed chain, you should definitely replace
your chain
. You may also need to replace your cassette. If it
does go in (like in the picture on the right), we know that it is
beyond 0.75% worn and should be replaced. You will most probably
have to replace your cassette/sprockets too.
If you are running an 8, 9 or 10 speed chain, we would recommend your chain be replaced if the chain checker almost slots in at the 0.75% measurement.

5. We then repeat the above steps along a separate section of the chain to ensure we are getting an accurate reading.


In Summary:


Is there anything you can do to prolong chain life?

In addition to regularly checking your chain length to check how worn it is, you can prolong the life of your chain by taking the following actions:

  1. Regular clean your chain with a rag and some degreaser or a specialist chain cleaner;
  2. Use a good quality chain oil (‘dry lube’ in summer and ‘wet lube’ in winter);
  3. Adopt the principle of ‘little and often’ when it comes to oiling/lubing your chain. If your chain has too much oil on it, it attracts debris that mixes with the lube and acts like a grinding paste. This will wear your chain and components;
  4. After riding in the wet/rain, use a water displacer such as GT85 which you spray on to the chain (try not to get it on your brakes/braking surfaces). Then apply fresh lube.
  5. Avoid riding crossed chained. Not only can this cause your chain to rub on your front derailleur, it is also a quick way to prematurely wear your chain, cassette and chain rings. With a Shimano 105 group set, this could see you looking at replacement parts totalling around £125!


We hope you found this useful. Please do feel free to share it amongst your friends and/or on social media.

Best wishes and happy cycling!

The havebike team

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