How much chain wear is too much?

Discussion in 'Australia and New Zealand' started by Andrew Swan, Jun 2, 2003.

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  1. Andrew Swan

    Andrew Swan Guest

    While cleaning my chain tonight, I noticed it was a bit worn, e.g.

    - when laid on a table, there was a noticeable difference in length between being fully stretched
    and with the ends compressed together (keeping it straight the whole time)
    - it can be shaped sideways into about 3/4 of a full circle (sounds bad, huh)

    I'm wondering when I should (or more likely, how long ago I should have) replace it - is there
    some standard yardstick for telling when a chain is too worn? I've heard of tools that measure
    wear by the amount of stretch - are these worth the money, or would it be enough just to measure
    the change in distance between a given number of links, in which case how much change (e.g. as a
    %) would be too much?

    In case it makes any difference, my (road) bike has a 7-speed cluster, triple chainring, and the
    chain is the Shimano "narrow" type.

    Thanks for any help,

    Andrew
     
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  2. Hippy

    Hippy Guest

    "Andrew Swan" <[email protected]> wrote in message
    news:[email protected]...
    > I'm wondering when I should (or more likely, how long ago I should have) replace it - is there
    > some standard yardstick for telling when a chain is too worn? I've heard of tools that measure
    > wear by the amount of stretch - are these worth the money, or would it be enough just to measure
    > the change in distance between a given number of links, in which case how much change (e.g. as a
    > %) would be too much?

    "The standard way to measure chain wear is with a ruler or steel tape measure. This can be done
    without removing the chain from the bicycle. The normal technique is to measure a one-foot length,
    placing an inch mark of the ruler exactly in the middle of one rivet, then looking at the
    corresponding rivet 12 complete links away. On a new, unworn chain, this rivet will also line up
    exactly with an inch mark. With a worn chain, the rivet will be past the inch mark. If the rivet is
    less than 1/16" past the mark, all is well. If the rivet is 1/16" past the mark, you should replace
    the chain, but the sprockets are probably undamaged. If the rivet is 1/8" past the mark, you have
    left it too long, and the sprockets (at least the favorite ones) will be too badly worn. If you
    replace a chain at the 1/8" point, without replacing the sprockets, it may run OK and not skip, but
    the worn sprockets will cause the new chain to wear much faster than it should, until it catches up
    with the wear state of the sprockets. If the rivet is past the 1/8" mark, a new chain will almost
    certainly skip on the worn sprockets, especially the smaller ones.

    From the bible: http://www.sheldonbrown.com/chains.html

    HTH hippy
     
  3. Mike

    Mike Guest

    Andrew Swan wrote:
    > While cleaning my chain tonight, I noticed it was a bit worn, e.g.
    >
    > - when laid on a table, there was a noticeable difference in length between being fully stretched
    > and with the ends compressed together

    I wouldn't trust that. Measure it stretched, as Sheldon says in hippy's post.

    > I'm wondering when I should (or more likely, how long ago I should have) replace it

    1) keep it until it starts to jump under load on some gears. By then, you will need a new cassette
    though. Less effort for you.

    2) if you replace it earlier, (more often) you might save money by a longer cassette life. It
    depends on the relative value of chains and gears, I guess. A good idea if you have alloy
    chainrings, which wear more easily on an old chain.
     
  4. Andrew Swan

    Andrew Swan Guest

    Thanks for both answers, they are a big help.

    Turns out my chain is stretched by almost 1/8", so I'll take the second poster's advice and just run
    with it until it starts misbehaving.

    I'll know better with my next chain and gear set!

    Thanks again,

    &roo
     
  5. Dclain

    Dclain Guest

    Just so you know, if you replace your chain, be prepared to replace the whole back cluster, possibly
    the derail too. I found this out the hard way.

    "Andrew Swan" <[email protected]ndrewswan.com> wrote in message
    news:[email protected]...
    > While cleaning my chain tonight, I noticed it was a bit worn, e.g.
    >
    > - when laid on a table, there was a noticeable difference in length between being fully stretched
    > and with the ends compressed together (keeping it straight the whole time)
    > - it can be shaped sideways into about 3/4 of a full circle (sounds bad, huh)
    >
    > I'm wondering when I should (or more likely, how long ago I should have) replace it - is there
    > some standard yardstick for telling when a chain is too worn? I've heard of tools that measure
    > wear by the amount of stretch - are these worth the money, or would it be enough just to measure
    > the change in distance between a given number of links, in which case how much change (e.g. as a
    > %) would be too much?
    >
    > In case it makes any difference, my (road) bike has a 7-speed cluster, triple chainring, and the
    > chain is the Shimano "narrow" type.
    >
    > Thanks for any help,
    >
    > Andrew
     
  6. Andrew Swan

    Andrew Swan Guest

    DClain wrote:
    > Just so you know, if you replace your chain, be prepared to replace the whole back cluster,
    > possibly the derail too. I found this out the hard way.

    Replacing the whole back cluster makes sense, but why the derailleur as well? Surely it doesn't wear
    the same way or to the same extent as the load-bearing components? Or do you just mean the jockey
    and tension wheels (the little plastic cogs on the derailleur)?
     
  7. Mike

    Mike Guest

    DClain wrote:
    > Just so you know, if you replace your chain, be prepared to replace the whole back cluster,
    > possibly the derail too. I found this out the hard way.

    If that happens, there is no point changing the chain. Put the old one back on, and keep until it
    starts jumping. Then replace together with the cluster. But why would you need a new derailer?
     
  8. chippa

    chippa New Member

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    Yep.....did the same thing, didn't change it until it played up. Play up it did and I ended up in hospital with 4 busted bones. Change it I say.
     
  9. Mike

    Mike Guest

    chippa wrote:
    > Yep.....did the same thing, didn't change it until it played up. Play up it did and I ended up in
    > hospital with 4 busted bones. Change it I say.

    What? It was just starting to skip, and you came off ?! How? Riding hard while standing on the
    pedals with no cleats or toe-straps??? Or did your chain fail completely?
     
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