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Chain wear ?

The good doctorThe good doctor Posts: 307
edited November 2007 in Workshop
Whilst cleaning my steed this morning I noticed that the chain does not sit tightly on the chainring. The rear wheel is correctly positioned so is this a case of wear and tear ?

Thanks

Posts

  • cougiecougie Posts: 22,512
    How far can you lift the link off the chainring ? And yes thats usually a sign of wear.
  • JWSurreyJWSurrey Posts: 1,173
    Park Tool do a chainwear indicator that costs about a fiver. Should be available on Wiggle - In fact, it (or same design) was shown in a C+ article!

    There is some sort of method involving lifting the chain up - no doubt someone will be along with the answer in a minute.

    In the meantime, there's a rough calc. on the page so you can measure if you have wear, plus some good photos:
    http://www.sheldonbrown.com/chains.html
  • A good quality steel ruler, marked in old money, is your friend.

    Chain links are exactly half an inch from pin centre to pin centre, so 24 links should be 12 inches long.

    As a chain wears, this distance increases because the pivoting surfaces inside the chain get sloppy.

    If 24 links are are 12 1/16in long, then it's time to think about replacing the chain and if they've got to 12 1/8in, you will probably have to replace the sprockets and chainrings too, as the lengthened chain will have worn them to the point where a new chain will slip.
    John Stevenson
  • Thanks v much.
  • pneumaticpneumatic Posts: 1,989
    A good quality steel ruler, marked in old money, is your friend.

    Chain links are exactly half an inch from pin centre to pin centre, so 24 links should be 12 inches long.

    As a chain wears, this distance increases because the pivoting surfaces inside the chain get sloppy.

    If 24 links are are 12 1/16in long, then it's time to think about replacing the chain and if they've got to 12 1/8in, you will probably have to replace the sprockets and chainrings too, as the lengthened chain will have worn them to the point where a new chain will slip.

    Thank you for this excellent advice, John. I performed this simple procedure on my winter bike today. Since I couldn't get it down to anything less than 12 1/5, I am presumably looking at new chain, new chainrings and new cassette. The gears still change (with a little nudge here and there), but I feel so irresponsible!!

    Mind you, after 5000 miles in six countries, the only maintenance bills I have had are two new tyres, four new brake blocks and a couple of rolls of bar tape, so I can't really complain.


    Fast and Bulbous
    Peregrinations
    Eddingtons: 80 (Metric); 60 (Imperial)

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