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Shifts up but not down - what gives?

mudcow007mudcow007 Posts: 3,861
edited March 2012 in The workshop
my bikes has been developed an issue in that it shifts up fine, but not down like the dérailleur doesn't have enough pull in the spring to pull the cable - if that makes sense?!

bike is 4 months old so derailleur should still be ok

any ideas?
Keeping it classy since '83

Posts

  • MrChuckMrChuck Posts: 1,663
    Drag in the cable?
    If the wire has too much drag on the outer when too much censored gets in there it can be too much for the spring to overcome. Things like too tight a loop before the cable enters the mech can make it worse.
    Easily checked by unhooking the cable from the mech- obviously you'll need to set your gears up from scratch if you do this though!
  • cooldadcooldad Posts: 32,904
    Cables. And I think you mean it shifts down fine - down = lower gear/bigger cog. Up=higher gear, smaller cog.
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  • FoldingJoeFoldingJoe Posts: 1,327
    When you say "issues", do you mean doesn't shift at all, or is just hesitant?

    Seen as though your bike isn't that old it could just be cable stretch, so you may need to tighten the cable slightly.
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  • phy2sll2phy2sll2 Posts: 680
    Have a look inside the shifter, you may find the cable has frayed and is getting stuck when you 'release' the tension on shifting up.
  • mudcow007mudcow007 Posts: 3,861
    thanks for the replies i reckons i need about a 1/4 of a turn on the barrel adjuster

    as it seems to be getting noisier by the day, so it must be cable

    just threw me the way it was ok shifting up (going from say 5 sprocket to 7) but going down it wouldnt shift unless i shifted down again an it would clunk down
    Keeping it classy since '83
  • bails87bails87 Posts: 13,317
    So it will easily shift onto a phsyically smaller (harder) cog, but not to a physically larger (easier) cog?

    Sounds like the cable is sticking. Unhook the outers from the cable guides, see how freely they move along the inner cable. Replace/WD40 as necessary.
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  • The RookieThe Rookie Posts: 27,748
    Unless it's rapid rise, cables usually cause an issue going to a up, the OP is having issues going down through the gears when the shifter would be pulling cable, indexing would be most likley, unless its an RR of course!

    Simon
  • bails87bails87 Posts: 13,317
    Unless it's rapid rise, cables usually cause an issue going to a up, the OP is having issues going down through the gears when the shifter would be pulling cable, indexing would be most likley, unless its an RR of course!

    Simon
    You're right, my brain was muddled!

    In that case, I agree with you, a bit of cable stretch knocking the indexing out is most likely.
    MTB/CX

    "As I said last time, it won't happen again."
  • mudcow007mudcow007 Posts: 3,861
    ok ok you both earned your cookies today

    6a00d8341c660253ef00e54f659c708833-800wi.jpg

    i have been playing around witht e barrel adjusters an i think ive sorted it

    fanks
    Keeping it classy since '83
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