Slack chain

The good doctor
The good doctor Posts: 307
edited January 2008 in Workshop
Just a quickie I hope, but my new chain is very slack when on the smaller chainring and the rear mech is almost touching the rear cassette. Both were replaced recently if this helps other than that the chain runs smoothly.
Thanks

Comments

  • terongi
    terongi Posts: 318
    Try this test:

    Put the bike into the highest gear (ie biggest chainring and smallest sprocket). Now look carefully at the jockey wheels of the rear derailleur. They should be pretty much aligned vertically to each other.

    If not then:

    If the bottom jockey wheel is too far to the right then the chain is too tight: add a link until the jockey wheels are vertical.

    If the bottom jockey is too far to the left, then the chain is too slack: remove links until the jockeys are vertical.
  • The good doctor
    The good doctor Posts: 307
    Thanks will try it out. Out of curiosity as I have replaced a 9 speed chain old for new should any adjustment have been necessary?
    Thanks again
  • terongi
    terongi Posts: 318
    The good doctor wrote:
    Thanks will try it out. Out of curiosity as I have replaced a 9 speed chain old for new should any adjustment have been necessary?
    Thanks again

    When you buy a new chain, they usually give you more links than you need (obviously to cope with different length chainstays, different size chainrings and sprockets etc on different people's bikes).

    So if you simply put on the new chain straight out of the packet, then it will almost certainly be too long.

    When replacing a chain, you should count the number of links in the old chain and replicate that in the new chain by removing links. Don't do it by measuring the length of the old chain, because usually the reason why you replace a chain is because it has "stretched", so you don't want to replicate that.
  • The good doctor
    The good doctor Posts: 307
    Thanks Terongi, oh for some more common sense. :wink:
  • giant_man
    giant_man Posts: 6,878
    This is a good thread and one which I can relate to cos I just replaced my cassette and chain onto new wheels actually. I did it by counting the links on the old chain and replicating that on the new one.

    However, the new one now seems to be too long cos of the jockey wheels not being vertical. Excellent advice from terongi which I will use and adjust the new chain.

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