Front derailleur adjustment

flester
flester Posts: 464
edited December 2013 in MTB workshop & tech
Help!

Spec Hardrock 2003

42/32/22 chainrings
Acera derailleur
32-11 8 speed cassette.

I fitted new cassette and chain.

I can adjust so that 1st cog/middle chainring combination does not rub, but then the 2 or 3 highest gears rub. I definitely had it working right before. Pretty sure derailler height, angle, tension and limit screwas are set right.

The new chain was sold as a 6/7/8 speed,
http://www.chainreactioncycles.com/ie/e ... -prod38332
could it be wider than the original that came with the 8-speed setup?
'I do not believe in the three-speed gear at all', the sergeant was saying. 'It is a newfangled instrument, it crucificies the legs, the half of the accidents are due to it.' (From 'The Third Policeman')

Comments

  • flester
    flester Posts: 464
    Yes I've followed Park Tool's instructions too.

    One thing I noticed is theres a lot of free play in the derailleur i.e. if I wiggle it when on the middle chainring it moves quite a bit
    'I do not believe in the three-speed gear at all', the sergeant was saying. 'It is a newfangled instrument, it crucificies the legs, the half of the accidents are due to it.' (From 'The Third Policeman')
  • oxocube1
    oxocube1 Posts: 651
    The 'free play' in the mech is normal, as long as the mount is not physically twisting around the seat tube.

    It could be the case that the chain is slightly wider. I was always under the impression that 5,6, and 7 speed setups used the same chain, but 8 speed was slightly thinner, just like 9 and 10 speeds are thinner respectively.

    Other than that it possibly sounds like it may need a little more tension from the barrel adjuster on the shifter. Also be aware that adjusting the lower limit screw does have an effect on the mech when its in the middle chainring position.
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  • The Rookie
    The Rookie Posts: 27,812
    An 8 speed chain is the same as 5,6,7 speed, OC1 is mistaken.

    Did you move the mech at all when changing the chain, could it be you've changed the toe in/out?
    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.
  • flester
    flester Posts: 464
    I did move the mech down closer (parktool recommends with in 1-2mm from the largest chainring) but then put it back where it was. I did rotate it slightly but again put it back to original setting. Even if the chain were slightly wider it could only account for a mm at most. What puzzles me is that it was right before. Don't think the frame has got bent or had a significant impact.

    I would not have thought that lower limit screw had any effect in the middle chainring position though?
    'I do not believe in the three-speed gear at all', the sergeant was saying. 'It is a newfangled instrument, it crucificies the legs, the half of the accidents are due to it.' (From 'The Third Policeman')
  • The Rookie
    The Rookie Posts: 27,812
    Most likely you haven't actually put it back where you did before and you are either running toe (in or out) or not running it (sometimes they need some depending on the chainline at front AND rear).

    Why not take a photo from directly overhead with the chain going to 1st and 8th gear in turn so we can see what is happening,also confirm that on the middle ring the chain sits vertically on the middle flat portion of the mech.

    No effect from the L screw.
    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.
  • flester
    flester Posts: 464
    Thanks, will take photo. The cage is not a straight line so hard to see if its toed in/out or not. I can see the original height cos the frame is marked, but not the toe angle. I can see how the mid chainring/largest cog combo would have more of an angle. Its a handy gear to use, even though the angle is extreme.
    'I do not believe in the three-speed gear at all', the sergeant was saying. 'It is a newfangled instrument, it crucificies the legs, the half of the accidents are due to it.' (From 'The Third Policeman')
  • flester
    flester Posts: 464
    Photos here. Didn't take in all gears, just the extremes. This is adjusted so that its just abour ok in 1st gear on middle ring but already rubbing in 5th on outer ring
    'I do not believe in the three-speed gear at all', the sergeant was saying. 'It is a newfangled instrument, it crucificies the legs, the half of the accidents are due to it.' (From 'The Third Policeman')
  • The Rookie
    The Rookie Posts: 27,812
    Photo's are a bit dark but it's looking toed out rather heavily ( rear of the cage towards the bike centreline).
    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.
  • flester
    flester Posts: 464
    Thanks for looking. I did toe it out a bit but the angle of the photos is exaggerating it. It didn't really help, and the cage is already nearly touching the tyre when on inner ring. I think I'll just give up on gears 1 and 2 in middle chainring. I can get virtually identical ratios on small ring anyway. And I do want to use the high gears on the outer ring, cos I usually cycle a few miles by road to get to the woods.
    'I do not believe in the three-speed gear at all', the sergeant was saying. 'It is a newfangled instrument, it crucificies the legs, the half of the accidents are due to it.' (From 'The Third Policeman')
  • flester
    flester Posts: 464
    Got is as good as it going to get by toeing it in a fraction. Think I'll stop fecking around with it now. Thanks to all of ye.
    'I do not believe in the three-speed gear at all', the sergeant was saying. 'It is a newfangled instrument, it crucificies the legs, the half of the accidents are due to it.' (From 'The Third Policeman')

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