Repairing my gears: help sought.

Phil_D
Phil_D Posts: 467
edited February 2012 in Road buying advice
I had an event on Saturday that lead to my rear mech getting caught in my rear wheel and it being mangled, together with the chain. The result is I need to buy some new stuff.

I am told that replacing the rear mech and the chain is not a good idea as the chain rings and cassette will not agree with the new chain, and will not work properly.

Consequently I think I will have to change the chain ring as well.

The question I have relates to the rear mech and cassette, and compatability with the shifters. The current rear cassette is an 8 speed Shimano Sora, and the rear mech is Shimano Tiagra. The shifter I am unsure about.

I am happy to get an 8 speed cassette, Shimano Tiagra I think. But I am not sure what I need in terms of rear mech. Will a 10 or 9 speed mech fit, or will I need an 8 speed mech to match the cassette?

Comments

  • Wooliferkins
    Wooliferkins Posts: 2,060
    There are still Sora 8 speed rear mechs about
    Neil
    Help I'm Being Oppressed
  • johndoran
    johndoran Posts: 69
    Unless the cassette or chain rings are showing signs of wear then just replace the rear mech and chain if that is also damaged. Crikey if I changed the cassette and chain rings every time I changed my chain I'd be skint.
  • craker
    craker Posts: 1,739
    You may get away with just replacing the chain, it depends how old and worn your existing setup is. If the chain slips on the cassette get a new cassette, if the chain slips on the chainrings get new chainrings. It's all beginning to be rather expensive :-(

    If I was replacing lots of comopnents I'd try and stay with the same technology for compatibility reasons. 8 speed stuff is a fair amount cheaper than 9 / 10 speed anyway.

    Check the mech hanger; if it's bent you may need to invest time and money getting it straight or it will throw your shifting out.
  • Phil_D
    Phil_D Posts: 467
    Wooliferkins wrote:
    There are still Sora 8 speed rear mechs about

    Cheers but my old mech is Tiagra and I would prefer a like for like. Will a 9 speed match an 8 speed if I can't find a decent enough 8 speed?
  • Phil_D
    Phil_D Posts: 467
    craker wrote:
    You may get away with just replacing the chain, it depends how old and worn your existing setup is. If the chain slips on the cassette get a new cassette, if the chain slips on the chainrings get new chainrings. It's all beginning to be rather expensive :-(

    If I was replacing lots of comopnents I'd try and stay with the same technology for compatibility reasons. 8 speed stuff is a fair amount cheaper than 9 / 10 speed anyway.

    Check the mech hanger; if it's bent you may need to invest time and money getting it straight or it will throw your shifting out.

    Thanks for that. I will start with the mech and chain and go from there. Oh, and the hanger is snapped in two.
  • johndoran
    johndoran Posts: 69
    I'm sure a 9 speed rear mech will work as its the changer that is indexed. I'm using a 9 speed ultegra rear mech with 10 speed changers and only changed the jockey wheels and chain. You wouldnt need to do that with a 9/8 speed.
  • Phil_D
    Phil_D Posts: 467
    johndoran wrote:
    I'm sure a 9 speed rear mech will work as its the changer that is indexed. I'm using a 9 speed ultegra rear mech with 10 speed changers and only changed the jockey wheels and chain. You wouldnt need to do that with a 9/8 speed.

    My thoughts were that as long as the limit screws are in the right place it should be fine. But I know nothing.
  • smidsy
    smidsy Posts: 5,273
    Rear mech will be fine as they are not speed specific. Just tune it and off you go.
    Yellow is the new Black.
  • craker
    craker Posts: 1,739
    smidsy wrote:
    Rear mech will be fine as they are not speed specific. Just tune it and off you go.

    Really? I'm in the process of upgrading my drivetrain from 9 speed to 10 speed. I fitted the new chain last night and it kept dropping off the bottom jockey wheel of the mech (long cage tiagra 9) (ie ending up in the gap between the jockey wheel and the cage). It could be a set-up thing. I had thought I probably need a 10 speed specific mech...
  • itsnotarace
    itsnotarace Posts: 518
    craker wrote:
    Really? I'm in the process of upgrading my drivetrain from 9 speed to 10 speed. I fitted the new chain last night and it kept dropping off the bottom jockey wheel of the mech (long cage tiagra 9) (ie ending up in the gap between the jockey wheel and the cage). It could be a set-up thing. I had thought I probably need a 10 speed specific mech...

    10 speed chains are thinner, in your case you would need a new rear mech or 10 speed jockey wheels
  • Phil_D
    Phil_D Posts: 467
    So to clarify: I will be OK to buy a 9 speed rear mech and use it with an 8 speed cassette. Yes?
  • keef66
    keef66 Posts: 13,123
    Yes. The rear mech does what the shifter tells it to do
  • Phil_D
    Phil_D Posts: 467
    keef66 wrote:
    Yes. The rear mech does what the shifter tells it to do

    Thanks.

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