Triple Double ?

conceptsails
conceptsails Posts: 51
edited March 2012 in MTB workshop & tech
i have just swapped my 2011 XT triple chainset for a 2012 double however I am getting way too much chain rub on the front mech. My thoughts are...
Is it the shifters fault... In road double shifters there is a half shift to fractionally move the mech off the rubbing chain. does the new 2012 xt double shifter do this?

Is it the Mech height? its on a full sus so in the stand I get nearly all the gears without any rub. However when I sit on the bike it lowers the clearance meaning that the chain starts to rub on the outside 'ramp' of the mech

Is it the mech? Do the double specific mechs have less of a 'ramp' so it doesnt rub?

Comments welcome.

Comments

  • supersonic
    supersonic Posts: 82,708
    What size chainrings are you running?
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  • conceptsails
    conceptsails Posts: 51
    40 - 28
  • Anonymous
    Anonymous Posts: 79,667
    Rubbing as in hitting the side of the mech cage?

    If so it would probably just need re-adjustment (stop limit screws for the high and low gear and fiddle with the barrel adjuster until the cage is clearing on both gears).

    If it's hitting the top of the mech cage then I'd guess you have a bigger chainring on there than you used to have, in which case the mech height would need adjustment I think. Maybe makes sense if the suspension compression is causing it to hit.

    Is the mech and/or shifter the triple and you've just changed the chainset or is the whole lot new?
  • conceptsails
    conceptsails Posts: 51
    Just changed the chainset, everything else is triple, rubbing on side of mech on the bit i call the ramp where the cage sort of dents inwards at the top of the cage to push the chain off the outer ring during a downshift. (hope that makes sense) this ramp is normally out of the way above the chain when in the small ring but the suspension travel lowers it down onto the chain causing the rub. but no end of adjustment seems to solve it, i get about 4 gears i can use in each ring without rubbing noise the adjustment simply changes which 4!
  • 1mancity2
    1mancity2 Posts: 2,355
    Have you adjusted the mech screws so it only allows the shifter to click twice?
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  • bennett_346
    bennett_346 Posts: 5,029
    1mancity2 wrote:
    Have you adjusted the mech screws so it only allows the shifter to click twice?
    You mean once?
  • 1mancity2
    1mancity2 Posts: 2,355
    bennett_346 wrote:
    1mancity2 wrote:
    Have you adjusted the mech screws so it only allows the shifter to click twice?
    You mean once?

    Oh yeah! Blonde moment
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  • bennett_346
    bennett_346 Posts: 5,029
    1mancity2 wrote:
    bennett_346 wrote:
    1mancity2 wrote:
    Have you adjusted the mech screws so it only allows the shifter to click twice?
    You mean once?

    Oh yeah! Blonde moment
    aha just clarifying you meant what i thought you did :wink:
  • conceptsails
    conceptsails Posts: 51
    Yep using bottom and middle positions and stopper screwed the big ring shift
  • The Rookie
    The Rookie Posts: 27,812
    You need to try and tweak the height of the mech so that in neither of the new gears is the chain running past one of the ramps that fell between the ratio's of the triple setup I think.

    Simon
    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.
  • nicklouse
    nicklouse Posts: 50,675
    and nope there is no trimming facility.

    you do need to fully rest the mech for position and for start and finish positions.
    and from the FAQs
    4. Nine speed front dérailleurs can be used with 10 speed front shifters, but do not work optimally if used with a 10 speed crankset. Nine speed front dérailleurs and cranksets can be used with 10 speed chains and front shifters. A nine speed shifter can be used to shift a 10 speed dyna sys front dérailleur.
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  • njee20
    njee20 Posts: 9,613
    Mech'll need moving up significantly to compensate for the now much bigger inner ring.
  • conceptsails
    conceptsails Posts: 51
    winner. Thanks for that.

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