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New chain

dbodendboden Posts: 349
edited April 2009 in MTB workshop & tech
Hello I have bought and fitted a new SRAM PC991 chain.
The rear cassette is in good condition, but the front middle ring seems a little worn, obviously as this gets used 75% of the time.
Would it be best to replace this?
Will it damage the chain if I don't?

Posts

  • hucking_fellhucking_fell Posts: 1,056
    The alreadly worn chainring will wear more quickly, especially if aluminium. The chain will wear more quickly also but not as much 'cos it's steel.
    More freerange chicken than Freeride God
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  • It would be better to do it at the same time if you can, then your drivetrain's sorted for a good while.
    Be happy, communicate happiness.
  • dav1dav1 Posts: 1,298
    if you replace a chain before it gets to 1% usually thats all you have to change. After a few chains the whole lot needs to be done ideally.
    Giant TCR advanced 2 (Summer/race)
    Merlin single malt fixie (Commuter/winter/training)
    Trek superfly 7 (Summer XC)
    Giant Yukon singlespeed conversion (winter MTB/Ice/snow)

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  • supersonicsupersonic Posts: 82,708 Lives Here
    If you have fitted it, and there are no probs, I'd leave it!
  • .blitz.blitz Posts: 6,197
    dboden wrote:
    The rear cassette is in good condition, but the front middle ring seems a little worn, obviously as this gets used 75% of the time.Would it be best to replace this?Will it damage the chain if I don't?
    I used to get suckered in with this every time I bought anything to do with the drivetrain. New chain ? Yessir, you'll need a new cassette and probably new chainrings; maybe even new cranks & shifters :roll:

    So one day I bought just the chain and - surprise surprise - the drive train didn't fall to bits and - shock horror - the gears still shifted just great. If the teeth on the cassette/chain rings are hooked then maybe they need replacing but otherwise it's a waste of time and money.
  • dbodendboden Posts: 349
    Update: Chain replaced,

    I then found that the front middle seemed to stick? I was actually convinced it needed changing, so I did,

    It now runs really sweet at the front, I then had to re-index the gears slightly, (1st time I have done this, but all the gears seem to now work fine, up and down)

    1 problem remaining, the chain seems to slip slightly at the rear, under hard pedaling,

    Could this be the rear cassette that also now needs replacing?
    Or is this common, and the chain will bed in?

    I am assuming the indexing cannot affect this?
  • nicklousenicklouse Posts: 81,520 Lives Here
    if the chain is slipping over the cogs then yes. As long as the chain is the correct length and there are no stiff links.

    If it is actually the cassette slipping over the hub then that is something else
    "Do not follow where the path may lead, Go instead where there is no path, and Leave a Trail."
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  • dbodendboden Posts: 349
    After what I have been doing, I am just presuming that it is the chain slipping over the cassette, As it only happens with heavy pressure whilst cycling, it is very difficult to actually see what is happening?
  • MancunianfightingcatMancunianfightingcat Posts: 2,054
    edited April 2009
    I always replace my chain at 0.75% stretch. Since I got my new bike last May, I've had 5 chains on it, including the one it came with. The cassette has been fine until the last change, so that got replaced then, the front chain rings are still fine though.

    I'm tempted to see which is most economical, regular chain changing, or waiting until the whole lot is knackered and replacing it all! Has anybody ever worked it out?

    SRAM 991 chain - £22.50 *4 = £90 (plus the original)
    SRAM 990 Cassette - £47.50
    RaceFace 32t Team Chain ring - £30 (not required yet)


    Probably not much in it. I've spent £137.50 on chains and a cassette.
    If I'd replaced the lot just once it would have been £103, but how many times would I have needed to change the lot?
  • dav1dav1 Posts: 1,298
    I always replace my chain at 0.75% stretch. Since I got my new bike last May, I've had 5 chains on it, including the one it came with. The cassette has been fine until the last change, so that got replaced then, the front chain rings are still fine though.

    I'm tempted to see which is most economical, regular chain changing, or waiting until the whole lot is knackered and replacing it all! Has anybody ever worked it out?

    SRAM 991 chain - £22 *4 = £90 (plus the original)
    SRAM 990 Cassette - £47.50
    RaceFace 32t Team Chain ring - £30 (not required yet)


    Probably not much in it. I've spent £137.50 on chains and a cassette.
    If I'd replaced the lot just once it would have been £103, but how many times would I have needed to change the lot?

    probably once or twice by now. I think it tends to work out cheaper to change chains (esp if you have three chainrings to worry about). Chaning vhains also prevents the degredation in performance from wear as well I tend to find.
    Giant TCR advanced 2 (Summer/race)
    Merlin single malt fixie (Commuter/winter/training)
    Trek superfly 7 (Summer XC)
    Giant Yukon singlespeed conversion (winter MTB/Ice/snow)

    Carrera virtuoso - RIP
  • glen4glen4 Posts: 250
    I got around 2000 offroad miles out of the standard transmission on my stumpy HT, before the chain snapped, still changing OK. Found out about this chain checking malarkey, and now change the chain at .75% stretch (about 250 miles), so now I'm doing 8 chains and two cassettes for 2000 miles, think I'll revert back to waiting til the chain snaps again LOL....... :lol:
    2009 Cove Handjob
    2009 Cove Hummer
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