Impossible indexing

scoi
scoi Posts: 103
edited May 2016 in MTB workshop & tech
Trying to fix the better half's bike, she always had trouble getting from the granny ring back to middle so had to go to big and then drop back.

This morning I undid everything and did a fresh set up following a guide. High and low set up was fine but middle cog was rubbing both sides when shifting cassette to 2 or 6 (7 speed).

All in all I tried with 4 different guides and none managed to end up with a smooth shift with no rubbing. It seems the cage is too small.

The only thing I can think is that the cable has become elastic over the years. Any other ideas?

Comments

  • apreading
    apreading Posts: 4,535
    Cage could be bent or hanger out of alignment? Years ago I despaired at trying to index mine, took it to the LBS and they diagnosed as bent cage. Didnt know much at the time so they talked me into a new mech but I think the old one could have been fixed... The new cage did sort the problem.
  • scoi
    scoi Posts: 103
    This is front so i presume there isn't a hanger. The cage looks to have no damage and it's parallel to the cogs but it narrows towards the middle which make sense from a design point of view but not for me on this bikr
  • larkim
    larkim Posts: 2,474
    Perhaps bodge it a little by widening the cage? Is it a decent mech, or a cheap entry level mech?
    2015 Canyon Nerve AL 6.0 (son #1's)
    2011 Specialized Hardrock Sport Disc (son #4s)
    2013 Decathlon Triban 3 (red) (mine)
    2019 Hoy Bonaly 26" Disc (son #2s)
    2018 Voodoo Bizango (mine)
    2018 Voodoo Maji (wife's)
  • bungalballs
    bungalballs Posts: 193
    If the cable guide is under the bottom bracket, check it doesn't move when changing gears or with cable tension. Also is the cable end all of the way home in the shifter? Do the inner cable run freely in the outers? Is the mech cage straight and parallel with the outer ring? A few extra checks to consider!
  • StinkinHippy
    StinkinHippy Posts: 160
    Bungalballs wrote:
    If the cable guide is under the bottom bracket, check it doesn't move when changing gears or with cable tension. Also is the cable end all of the way home in the shifter? Do the inner cable run freely in the outers? Is the mech cage straight and parallel with the outer ring? A few extra checks to consider!


    I would also put a drop of lube between the cable and the guide.. Had a nightmare getting consistent shifts trying to index mine, then an hour later I noticed the cable was sticking ever so slightly in the guide.
  • rockmonkeysc
    rockmonkeysc Posts: 14,774
    Could be all sorts of problems. Bent cage, worn cable, worn shifter, worn rings, worn chain, miss aligned mech, bent hanger, wrong width bottom bracket etc
    Transition Patrol - viewtopic.php?f=10017&t=13070235
  • The Rookie
    The Rookie Posts: 27,812
    A common issue is the height being set wrong so the steps on the side of the cage don't fall between where the chain is when in gear but are instead not aiding the shifting
    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.

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