Help! Deore XT need replacing?

gdcfc1
gdcfc1 Posts: 125
edited August 2016 in MTB workshop & tech
1999 Big Sur with original 9 speed Shimano Deore XT rear. Chain and rear cassette are new (less than 1 year old and chain is fine). However chain seems bit slack and mashes across gears when put strong pressure on pedals. Last act it did was to momentarily jam across, stop bike dead in tracks and pitch me off across pavement (thanks for the road rash. ouch!).

Gears change perfectly.

Is this tweakable or time to replace?

Recommendations for what to put on instead?

Will try and post a picture.....
looking into the +1

Comments

  • The Rookie
    The Rookie Posts: 27,812
    What does 'mashes across gears' mean?

    The only time I've had a chain jam solid is due to chain suck wrapping the lower chain up into the top run and that is usually a chainring wear issue when matching a worn ring to a new chain, but can be caused by muck off the front wheel.
    Currently riding a Whyte T130C, X0 drivetrain, Magura Trail brakes converted to mixed wheel size (homebuilt wheels) with 140mm Fox 34 Rhythm and RP23 suspension. 12.2Kg.
  • gdcfc1
    gdcfc1 Posts: 125
    The Rookie wrote:
    What does 'mashes across gears' mean?

    The only time I've had a chain jam solid is due to chain suck wrapping the lower chain up into the top run and that is usually a chainring wear issue when matching a worn ring to a new chain, but can be caused by muck off the front wheel.


    It means that the chain seems to jump between the rear cogs ... When pressure is applied to the pedal stroke, not on smooth normal pedaling but when effort is put in. This is a regular problem I am having - every ride. Chain seems to go across the teeth/cassette. Was Especially bad today at LBS when it threw me off - ouch.
    looking into the +1
  • The Rookie
    The Rookie Posts: 27,812
    is it a hardtail or a full sus?
    Currently riding a Whyte T130C, X0 drivetrain, Magura Trail brakes converted to mixed wheel size (homebuilt wheels) with 140mm Fox 34 Rhythm and RP23 suspension. 12.2Kg.
  • cooldad
    cooldad Posts: 32,599
    Gary Fisher hardtail I think.
    I don't do smileys.

    There is no secret ingredient - Kung Fu Panda

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    Parktools
  • gdcfc1
    gdcfc1 Posts: 125
    Hardtail.
    looking into the +1
  • swod1
    swod1 Posts: 1,639
    I think its time to fit a new front chain ring, the chain could be too loose on the worn teeth and then causing the gears to slip on the new cassette.

    you haven't messed with any of the limit screws on the rear derailleur?
  • The Rookie
    The Rookie Posts: 27,812
    Is the chain sized correctly? How did you size it?
    Currently riding a Whyte T130C, X0 drivetrain, Magura Trail brakes converted to mixed wheel size (homebuilt wheels) with 140mm Fox 34 Rhythm and RP23 suspension. 12.2Kg.
  • gdcfc1
    gdcfc1 Posts: 125
    Chain was fitted by LBS at same time as they replaced rear cassette. I guess they could have got it wrong, how do I assess? Just take out a link or two and try it?

    I had not messed with the limit screws but have tightened now to tighten the chain some. Did not resolve.
    looking into the +1
  • cooldad
    cooldad Posts: 32,599
    The limit screws have nothing to do with chain tension.

    Loosen everything off, read Parktools to find out how to index correctly and start from scratch.

    Chain should be measured around big ring/big cog, without going round the mech, plus a link.
    I don't do smileys.

    There is no secret ingredient - Kung Fu Panda

    London Calling on Facebook

    Parktools
  • The Rookie
    The Rookie Posts: 27,812
    Post a side on photo with the gears selected as big/big and it will be easy to see if the chain is sized close to correctly.
    Currently riding a Whyte T130C, X0 drivetrain, Magura Trail brakes converted to mixed wheel size (homebuilt wheels) with 140mm Fox 34 Rhythm and RP23 suspension. 12.2Kg.
  • gdcfc1
    gdcfc1 Posts: 125
    The Rookie wrote:
    Post a side on photo with the gears selected as big/big and it will be easy to see if the chain is sized close to correctly.

    Sorry have not figured out how to post a picture!

    Anyway LBS number 2 has it now and is replacing front chain ring. They measured the chain - and assessed it all. That seems to be the diagnosis so hopefully it will all be good soon.
    looking into the +1
  • The Rookie
    The Rookie Posts: 27,812
    To post a picture use an external host like tinypic or photobucket and then use the link and wrap with image tags and it will appear in the post.
    Currently riding a Whyte T130C, X0 drivetrain, Magura Trail brakes converted to mixed wheel size (homebuilt wheels) with 140mm Fox 34 Rhythm and RP23 suspension. 12.2Kg.

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