Worse for the Wear

I replaced the chain and cassette on my commuter today. It’s been around 2 years and I hadn’t checked the chain wear in ages. The chain was at the outer limits and the cassette was starting to show wear as well. I long ago quit keeping track of mileage so I can only guess, but I probably had around 3,000-3,500 miles on the drivetrain.

Checking the wear on your chain is simple. Hold a ruler along the chain and measure from center-to-center between a pair of pins that are one foot apart. If the measurement is exactly 12″ your chain is not worn. Anything over 12 1/16″ and it’s time to replace the chain. If the measurement is at or beyond 12 1/8″, both your chain and cassette are certainly shot.

Some mechanics recommend replacing the cassette each time you replace the chain. Others suggest every other chain replacement. I’ve found that a worn cassette can dramatically accelerate wear on a new chain, and a new chain may skip on an old cassette, so if the cassette is showing any wear at all, I’ll replace it when I replace the chain.

I like doing this stuff at home, but if wrenching isn’t your thing, you can always check your chain wear at home, and if you’re at the point of needing a replacement, your local bike shop can do the work for you. Whatever you do, it’s best to not wait until the chain starts skipping on the rear cogs; once it’s progressed to that point, your worn chain is also damaging your expensive chainrings up front.

7 Responses to “Worse for the Wear”

  • Mike says:

    My experience with replacing a drive train suggests that if your cassette is worn enough to require replacement, your sprockets should be replaced as well.

  • Doug R. says:

    Alan, I agree! change them as a set and have happy biking! The new Sram chains work with almost any cassette and I like the ease of “Power link” master links for chain swapping. Oh, on a social note, are you folks going to the tweed on the 27th? (The Rex ride was good fun). Dougman.

  • Alan says:


    “My experience with replacing a drive train suggests that if your cassette is worn enough to require replacement, your sprockets should be replaced as well.”

    The explanation I’ve heard is that the larger diameter of the chainrings spreads the load over a greater number of teeth which causes them to wear more slowly; this has certainly been my experience. I’ve been going through at least 2-3 cassettes for each chainring.


  • Brad says:

    Agreed on the large chainring wear. I still make sure to change my granny and typically my middle up front along with cassette and chain. I have a collection of usable big rings around so I haven’t totally learned my lesson though. Actually, I used to change chains at the first signs of wear and found myself changing cassettes soon after because my favorite cogs would skip. “Too late, argh!”. That became massively expensive in practice and I as loathe to change the granny up front, causing massive chainsuck issues. So now try to keep the chain relatively clean and then I just ride a set until the chain is destroyed and then change everything. Much cheaper.

  • Bob B says:

    The Park Chain Checker is a cool tool: http://bit.ly/d7xdWr
    8-speed cassettes and 5/6/7 speed freewheels on old bikes seem to last longer and cost less. I just replaced a chain & 5-speed freewheel for $35.

  • Molnar says:

    I was a bit perplexed until I read Bob B’s comment. I expect to get much more than 3,000 miles from a chain (I often exceed that with a tubular tire), although I admit that I, too, don’t measure, and to get two or three chains per freewheel/cassette. But I use 6- or 7-speed freewheels and 8-speed cassettes on my bikes that are multi-speed and not internally geared (i.e., racing road bikes), the newest of which is now 15 years old. Time flies when planned obsolescence is the rule, and replacement parts are hard to find – anyone know where I can get a 14-15-16-17-18-19 6-speed freewheel?

    Also, I second Bob B’s opinion of the Park Chain Checker: utterly unnecessary, but really neat.

  • Alan says:


    I too have gotten much longer chain life years back, though I don’t know if it was because of higher quality chains, fewer cogs, better maintenance, or something else. This particular chain and cassette were fairly well abused. I probably only cleaned the chain off of the bike once; the rest of the time I just squirted on lube and wiped with a rag. I’m going back to a regular routine of chain waxing and I expect to see much longer life on this next round.


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