Problems: Poor shifting & Chain suck behind cassette.

Nasty1
Nasty1 Posts: 108
edited December 2012 in MTB workshop & tech
Hi

I have been suffering a few problems with poor shifting and chain suck down behind the cassette. I am running Shimano SLX 2x9 setup with XT cassette and chain.
My shifting problems are whenever I try to shift into the biggest ring on the cassette, after a very short time the chain will suck down behind the cassette and it does not matter how I set it up or the set the stop screws up to prevent over shifting. I get this no matter whether I am in the large or granny ring up front!

I am beginning to think that it is an accumulation of both chain alignment and chain tension. I have attached some photos to show both.

I would appreciate some ideas on what the cause maybe and also whether I can change the chain alignment by playing with the spacers on the BB? I have 2 on the chainwheel side and 1 on the other. Is it just a case of what I take out from one side I put back into the other?

Cheers

Adie

IMG_0109_zps333ca370.jpg
Chain Alignment - big front to small rear

IMG_0110_zps85921291.jpg
Chain Alignment - big front to big rear

IMG_0112_zps7e322691.jpg
Chain tension - big front to big rear

IMG_0113_zpscf27362c.jpg
Chain tension - big front to little rear.

Comments

  • cooldad
    cooldad Posts: 32,599
    The low stop has to be wrong. If it's right it can't overshift.
    And you shouldn't be using big/big ever. Or you'll be saying bye bye to that nice shiny mech very soon.
    I don't do smileys.

    There is no secret ingredient - Kung Fu Panda

    London Calling on Facebook

    Parktools
  • Front has nothing to do with the rear. Adjust the stop more. CD - it's a 2x you should be able to use them all
  • cooldad
    cooldad Posts: 32,599
    Aaah fair enough. I have and I do.
    But issue has to be adjustment
    I don't do smileys.

    There is no secret ingredient - Kung Fu Panda

    London Calling on Facebook

    Parktools
  • cooldad
    cooldad Posts: 32,599
    It is nice and shiny though - I got that right.
    I don't do smileys.

    There is no secret ingredient - Kung Fu Panda

    London Calling on Facebook

    Parktools
  • Nasty1
    Nasty1 Posts: 108
    Yes it is shiny because it is maintained! If it was full of shit I could understand the shifting probs and you would see naff all.
    The chain sucks or overshifts on the change to the big rear sprocket and ends up behind the cassette down in the spokes. I can adjust the stop screw to the point that it will not shift onto the big sprocket and then slowly back it off until it will. Within a very short space of time it will suck or overshift down behind the cassette and chew into my spokes again. Running gear should be good (300 miles old)

    I take it the chain tension and alignment look OK?

    Cheers

    Adie
  • Ouija
    Ouija Posts: 1,386
    edited December 2012
    Chain is way too short. When in the big front small rear the derailleur should not look like this...

    IMG_0113_zpscf27362c.jpg

    That derailleur should be almost folded down with the chain going almost two thirds of the way round the sprocket. If it's that tight on the big front/small back it's no wonder it's nearly being ripped off when you move it up to the big ring on the cassette. This is usually caused by a short chain but can also be caused by tightening the tension screw that sets the rotation position of the derailleur. Look at the derailleur closely and you should see three screws. Two side by side which limit how far the derailleur can move furthest to the left and right and a third screw that sets chain tension. If that third screw is all the way in i'd highly recommend screwing it most of the way out so that the whole derailleur swivels forwards and slackens off chain tension.
  • Chain looks fine.

    I'd just adjust the b tension screw to how it should be set.

    I really don't think you could have set the limit correctly. It should just allow the chain to get to the big cog and certainly be no more than the middle of the cog matching the centre of the chain
  • The Rookie
    The Rookie Posts: 27,812
    Ouija's talking rubbish, with Chunkers thjat chain looks spot on for big big.

    What you're getting isn't chain suck....

    Upper wheel looks to close to the large ring, so that's the B-stop adjustment, the H stop is there precisely to stop over shifting so to me it sounds like normal adjustments needed.
    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.
  • Nasty1
    Nasty1 Posts: 108
    OK, I'll play with the B-Stop and fiddle some more.

    Cheers

    Adie
  • The Rookie
    The Rookie Posts: 27,812
    Check partktools or some of the guides on youtube, but make sure you get a good one!
    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.
  • Ouija
    Ouija Posts: 1,386
    Ouija's talking rubbish
    Upper wheel looks to close to the large ring, so that's the B-stop adjustment

    Nice to see you didn't actually read my post then..... The B stop adjustment was my recommendation too (though i didn't call it that by name).
  • The Rookie
    The Rookie Posts: 27,812
    I did, you said the chain was "way too short" which was rubbish......That mech looks spot on for big-big.
    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.
  • gezebo
    gezebo Posts: 364
    Tbh the jockey wheel looks too far away ('b' stop) imo! Although difficult to tell from the pics.

    Agree that its very likely to be related to h/l adjustment if everything else is done right. I'd try starting the indexing again from bottom up. If you get this right then it would be unlikely to require the top stop in the first place.
  • Ouija
    Ouija Posts: 1,386
    edited December 2012
    I did, you said the chain was "way too short" which was rubbish

    Ahh! A man who doesn't even read past the first sentence of a post...
    Ouija wrote:
    This is usually caused by a short chain but can also be caused by tightening the tension screw that sets the rotation position of the derailleur.

    Also
    That mech looks spot on for big-big.

    But not for Big/Small, which is what i believe i pictured and commented on.
  • Eh? That's all a load of rubbish.
  • The Rookie
    The Rookie Posts: 27,812
    Ouija wrote:
    Chain is way too short.
    Verdict is guilty....you were talking rubbish and and are now digging a bigger hole......
    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.
  • Nasty1
    Nasty1 Posts: 108
    Oi, I appreciate the advice guys but no need to biatch about each other like a bunch of girls!
  • supersonic
    supersonic Posts: 82,708
    The chain length is correct, so leave that as it is.

    Check the mech hanger is straight and the cassette sprocket is straight and true with no damaged teeth.

    With the stops, as little as an 1/8th of a turn can make the difference.
  • mattv
    mattv Posts: 992
    That chain does look slightly short. This bike is double and bash? There is no need to put that much tension on the mechanism spring. Two more pictures please, chain in little ring and smallest sprocket on the cassette. Also see if you can get one close up of the gap between the jockey wheel and cassette when in small chainring, big ring on cassette.
  • The Rookie
    The Rookie Posts: 27,812
    Sheesh, before saying that check out all the guides on chain length, big/big plus one pair of links, that looks spot on in big/big......
    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.
  • WindyG
    WindyG Posts: 1,099
    This thread is becoming pure comedy, must be the Xmas drink kicking in for people :-)
  • Nasty1
    Nasty1 Posts: 108
    Chain length is good (and as per photos), it was checked as per most guides and was already set at Big, Big plus 2 links. No need to argue anymore on chain length.

    My LBS gave the grace of a quick 5 min check on the stops and feel they are pretty good as I have got them and suggested I look else where on the setup or pay them silly money to reset the whole lot. I am goona strip it all out give it another deep clean and reset it again as the chain still comes off.

    Adie
  • cooldad
    cooldad Posts: 32,599
    Find a new LBS.
    I don't do smileys.

    There is no secret ingredient - Kung Fu Panda

    London Calling on Facebook

    Parktools
  • supersonic
    supersonic Posts: 82,708
    What about cable tension?
  • The Rookie
    The Rookie Posts: 27,812
    Surely if the high STOP is set correctly that shouldn't be relevant?
    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.
  • gezebo
    gezebo Posts: 364
    Surely if the high STOP is set correctly that shouldn't be relevant?

    If its set up correctly then the high stop is a back up preventing mech meeting spokes rather than an essential part of the indexing process.
  • The Rookie
    The Rookie Posts: 27,812
    But if the high stop is set right it should also stop the mech overshifting the chain behind the cassette.
    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.