Chorus Rear Mech Adjustment

beancounter
beancounter Posts: 369
edited March 2011 in Workshop
I should know this by now....

Anyway, just built up a bike with a Chorus 10 speed rear mech. All is well except I can't get the mech to complete the shift to the largest sprocket. It goes on to the sprocket but won't stay there. Slackening off the limit screw doesn't make any difference. Adding cable tension doesn't make any difference.

What else can I try?

Thank you

bc
2013 Colnago Master 30th Anniversary
2010 Colnago C50
2005 Colnago C40
2002 Colnago CT1
2010 Colnago World Cup
2013 Cinelli Supercorsa
2009 Merckx LXM
1995 Lemond Gan Team

Comments

  • keef66
    keef66 Posts: 13,123
    Is the mech hanger straight?? Ditto the frame??

    Failing that, are you lacking a spacer behind the cassette?
  • Monty Dog
    Monty Dog Posts: 20,614
    Also check:

    Is chain correct length?
    Is cable outer to rear mech too short?
    Is the inner cable clamped correctly?
    Make mine an Italian, with Campagnolo on the side..
  • beancounter
    beancounter Posts: 369
    All parts have been transferred from another frame and worked fine before, howver in answer to possibilities so far:-

    1. mech hanger looks straight to me
    2. I hope the frame is straight but it's not new so....
    3. there's no spacer behind the largest sprocket, never has been
    4. would a slightly too short chain cause this? it could be alink or two less than ideal
    5. cable outer seems fine, all other shifts ok
    6. cable is clamped correctly

    bc
    2013 Colnago Master 30th Anniversary
    2010 Colnago C50
    2005 Colnago C40
    2002 Colnago CT1
    2010 Colnago World Cup
    2013 Cinelli Supercorsa
    2009 Merckx LXM
    1995 Lemond Gan Team
  • stevec205gti
    stevec205gti Posts: 366
    And double check you're adjusting the correct limit screw :D
    Has the head wind picked up or the tail wind dropped off???
  • on-yer-bike
    on-yer-bike Posts: 2,974
    beancounter wrote:

    1. mech hanger looks straight to me


    bc

    It may 'look' straight but you still need to check its alignment. Brand new hangers still have to be bent slightly to fit the frame.
    Pegoretti
    Colnago
    Cervelo
    Campagnolo
  • onbike 1939
    onbike 1939 Posts: 708
    beancounter wrote:
    All parts have been transferred from another frame and worked fine before, howver in answer to possibilities so far:-

    1. mech hanger looks straight to me
    2. I hope the frame is straight but it's not new so....
    3. there's no spacer behind the largest sprocket, never has been
    4. would a slightly too short chain cause this? it could be alink or two less than ideal
    5. cable outer seems fine, all other shifts ok
    6. cable is clamped correctly

    bc

    This could be the problem and it would be as well to lube the pivots on the RD as winter gunk can mean that this does not travel the whole of its arc.
  • beancounter
    beancounter Posts: 369
    So just out of curiosity I wound on a lot more cable tension - 3 or 4 full turns of the adjuster. Lo and behold, chain now goes on to largest sprocket and stays there.

    But, changing back up through the gears I now can't get to the smallest sprocket - my final click of the shifter only gets me to the second smallest sprocket.

    It's like the 10 speed shifters have lost a speed.

    I'll just slink off to the LBS next week, Alan'll sort me out (again).............

    bc
    2013 Colnago Master 30th Anniversary
    2010 Colnago C50
    2005 Colnago C40
    2002 Colnago CT1
    2010 Colnago World Cup
    2013 Cinelli Supercorsa
    2009 Merckx LXM
    1995 Lemond Gan Team

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