When should you replace your bike chain?

Like it or not, bike chains “stretch” over time. Only by a small amount, but multiply that by the number of times each link passes over your chainrings, cassette and jockey wheels and you’ll quickly wear them out, if you don’t regularly replace your chain. A worn chain ultimately leads to the most common mechanical problem with bikes.

You’ll save money if you replace your chain before it becomes too worn. Normally, you can get through around 3 chains, before you need to replace the cassette. A new chain costs around £12-£15 and a new cassette costs around £20.

Rather than provide you with a “chains wear out after X miles” figure that will be a wild estimate, it’s easier to simply check for yourself.

Using Chain Wear Tool

Chain wear tool

The best way is to simply use a chain wear tool.

You slot the one side in to a chain link and then drop the other side on to the chain. If it slips in to the slot then it means the chain is worn.

You can also flip it to the 1.0 side to see if the chain is more than 1% worn. At which point you probably also need to replace the cassette.

Pull the chain

Pulling the chain

If you really don’t want to spend the money on a chain wear tool, then you can less accurately check by simply pulling the chain.

Start by shifting in to the biggest chainring at the front and smallest cog on the cassette.

Pull the chain at the front of the chainring. If it lifts off the chainring, then your chain is starting to wear. The chain shown in the image above is not worn.

Using a ruler

Measuring chain link

This should ideally be performed while the chain is still on the bike (I know I failed to do that in the picture above!). The zero mark of your chain should be placed directly above the centre of one of the chain pins. Then you need to count 12 complete links. A complete link would be everything you see in the picture above between the numbers 11 and 12.

The 12th link should line up with the 12 inches mark.

If the centre of the pin is 1/16” or 1/8” past the 12 inches mark, then you probably need a new chain. If it is more than 1/8” past the mark, you’ll have to replace the chain and cassette.

I’ll do a follow on post on replacing a chain. If you’d like to hear about it, then make sure you subscribe to our newsletter by using the form below.

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14 Responses to When should you replace your bike chain?

  1. Andrew 24/08/2012 at 10:30 am #

    My chain wear tool is 0.5% wear on one side and 0.75% wear on the other. When a chain gets to 0.5% I order a replacement, then replace when it gets to 0.75%.

  2. idavid 24/08/2012 at 8:47 pm #

    Being lazy rather than time poor, I get my LBS to replace block and chain every 1,500 miles or so. Seems to prevent most slippage, doesn’t cost a fortune and is cleaner, too.

  3. Andy 25/08/2012 at 12:44 pm #

    Since I was a kid I’ve NEVER replaced a chain, I’ve never had a problem.

    Clearly my bikes aren’t highly tuned speed machines, they are utilitarian and serve their purpose.

    I’ve had some of my bikes for over 10years each doing many 1000′s of miles, they are oiled regularly and continue to function well.

    If it ain’t broke don’t fix it.

    • Callum 26/02/2013 at 10:41 pm #

      Well said!

  4. Andrew 26/08/2012 at 2:18 pm #

    @Andy the chain will gradually wear and stretch over time, even with proper maintenance. If you don’t replace it, you will eventually either wear the whole drive chain out and start slipping or the chain will eventually fail i.e. snap. Now perhaps you haven’t been doing enough miles to have that happen yet, but that doesn’t mean it’s a recommended strategy for those who do.

    • Alan Moore 30/08/2012 at 12:06 pm #

      I think Andy’s point is still valid. When it slips or falls off, THEN you go to the shop and ask them to fit a new chain and sprockets.

      Mine are about shagged – after two years and c.5,000 miles.

  5. Oliver 26/08/2012 at 11:20 pm #

    Easy solution: ride a single speed with horizontal-ish dropouts!

  6. Chris Bolton 27/08/2012 at 10:59 pm #

    I used to use the Park Tools gauge and replace my chains when the gauge indicated that they had become worn. I have to say that I became sceptical as I ended up replacing chains that seemed to be working perfectly well? Yes I know if that if worn chains are left on the bike they will also impart corresponding wear on the cassette but they will still continue to work together well up to a point and at that point they should be both be replaced. The majority of cassette sprockets these days are made from thing gauge pressed steel and are arguably more prone to wear than the chain.

  7. GrahamL 29/08/2012 at 10:36 pm #

    Just bought a chain wear checker from Wiggle and a sturdier link remover a couple of weeks ago. Reading the above prompted me to use the checker for the first time. I’ve had my road bike a couple of years hence why I bough the tools. I was gob smacked when the .75 setting slipped into the links and shocked when the 1.0 setting did the same !!!!!!

    Already ordered a replacement chain. Luckily I had a new cassette fitted a few months ago so hopefully all ok. Removed the old chain in less than a minute with the other tool.

    I will be checking for chain wear more regularly now.

    • Andreas 30/08/2012 at 8:49 am #

      Pleased to hear you’ve spotted the issue and resolved it yourself – money saved ;)

      • GrahamL 31/08/2012 at 3:04 pm #

        Pleased to report chain sourced and fitted. Bit ‘nervy’ fitting it at first making such its the right length/type etc and double checking but all went ok. Next time no problem. Just for info I got it at a bargain from Chain Reaction Cycles. £15 pound from most other places but they have a ‘limited offer’ on at the moment on a lot of products and got it for £8.99 including postage. So quids in and a sense of satisfaction thrown in for good measure.

  8. oneten 15/09/2012 at 5:10 pm #

    Just facing the consequences of a worn chain myself – it meshes well on the cassette ans inner and middle chain wheels because these are probably worn by an equivalent amount, but the outer (large) ring slips really badly now. I can only assume because it has more teeth and has outlasted the chain.

    I’ve come to this conclusion because my son repaired a friend’s bike recently and discovered something odd.Her gear-shifter was stuck and she had ridden the bike for about a year with it stuck on one rear cog, using the front three chain-wheels as a means of changing gear. When he fixed the shifter, the chain would only continue to mesh on the one worn rear cog whereas the others either side slipped badly. Only way forward was a new freewheel block and chain. So uneven wear aslso seems to be a significant factor.

  9. Rob 21/01/2013 at 8:01 am #

    I just replaced a chain with not even 0.7% wear but about one year of usage (no idea about mileage). On the biggest rear cog I got slippage when on the granny ring, when torque is maximum on this cog. This often happens to me, generally from the second or third chain replacement, and always with just one or two of the cogs.

    I have therefore removed the new chain and replaced the old one to run for a bit more.

    Conclusion:
    1 – The 0.7% guide is no guarrantee that the cassette will not also need replacing
    2 – This probably happens as cumulative wear from previous chains
    3 – If I had just stuck with the original chain, I am not sure if the cassette really would have worn more quickly or not.
    4 – I wish I could buy cassettes by the cog? I am always throwing out complete cassettes with just one or two worn cogs (logically the ones that get the most use).

  10. oneten 22/01/2013 at 4:52 pm #

    Just a thought – and I haven’t tried this myself – but I am considering buying an extra chain now that I’ve had to replace the cassette and chain rings. I am thinking of rotating the use of both chains periodically so that they take longer to stretch and hopefully allow the cassette and chain-ring teeth to last longer. I suppose I would swap them when cleaning the drive-chain say every month.
    Anyone have any ideas about this ?

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