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Recurring front derailleur issue drving me spare

Samvan77Samvan77 Posts: 85
edited February 2013 in Road beginners
Hi All,

I seem to have the same issue recurring with my front derailleur and it is driving me spare now.

I have a 2012 Giant Defy 2 (Taigra Front Mech and shifters with Jagwires). The cabel tension keeps on slipping(going completely slack) rendering the front mech useless, I have tried tightening the tension on the barrel adjuster but does not seem to have any effect. This has happened a third time in the space of just other a month now, I have already taken my bike to two different "Reputable" LBS to sort out costing me about £15.00 a pop.

I am not much of a home mechanic but I am reluctant to keep on forking out £30.00 month to have this sorted, would any of you have any ideas or advice on this?

Posts

  • smidsysmidsy Posts: 5,273
    So does the cable slip in the clamp or is something else going on?
    Yellow is the new Black.
  • smidsy wrote:
    So does the cable slip in the clamp or is something else going on?

    Excuse my my ignorance here, but when you refer the cable slipping in the clamp are you referring to where the cable is tighened to the mech? If so how would I be able to tell if it has?

    Last night I managed to tigthen to tension of the cable using the barrel adjuster next to the shifter, however when I tried to gear down to the small chain ring I just felt the shifter click and the cable went slack again,
  • smidsysmidsy Posts: 5,273
    Yes the cable clamp on the mech.

    When it has gone slack is it still secure in the clamp?
    Yellow is the new Black.
  • Hi, thanks for the clarification. The cable goes completely slack underneath the downtube but is still secure in the clamp.
  • smidsysmidsy Posts: 5,273
    Well as the cable is secured at both ends it must be something else moving then (unles the cable magically extends in length) :? . Is the mech a band on one? If so is the band slipping on the seat tube.

    When you clamp it in the front mech make sure the mech is completely shifted to its smallest point (so make sure the trim is taken out by double checking there are no more clicks on the lever).

    Are the outers all properly seated?

    Failing that there must be something going on inside the Sti lever.

    What did the LBS say when they did It?
    Yellow is the new Black.
  • styxdstyxd Posts: 3,234
    Samvan77 wrote:
    smidsy wrote:
    So does the cable slip in the clamp or is something else going on?

    Excuse my my ignorance here, but when you refer the cable slipping in the clamp are you referring to where the cable is tighened to the mech? If so how would I be able to tell if it has?

    Last night I managed to tigthen to tension of the cable using the barrel adjuster next to the shifter, however when I tried to gear down to the small chain ring I just felt the shifter click and the cable went slack again,

    Erm, you should tension the cable when your shifter/mech have selected the small chain ring. Pull it finger tight and clamp it.
  • CiBCiB Posts: 6,098
    If the cable's going slack it can only be because something has moved or let go. Work it through logically.

    Is the nipple properly seated in the recess at the STI end?

    Is the thread on the barrel adjuster ok - I've found them quite easy to strip in the past so although they look ok when you fit the cable the tension pulls the outer adjuster over the inner and farks it all up again.

    Are you doing it with the lever in the lowest gear position and the mech over the small ring?

    Is the indexing at the end of its movement? Grasp the end of the cable carefully with a pair of pliers and pull whilst doing the 'change down to the smaller ring' action at the levers. You should be able feel it click through to the end of its travel.

    Is the outer cable fitted with a ferrule where it meets the frame hole? Bare ends can collapse under tension.

    Is the cable running properly through the plastic guide on the BB?

    Have you run the cable up to the correct side of the clamp on the mech? Shimano mechs won't change properly if you run the cable to the wrong side; when you give the lever a bit more grunt the cable might slip, the outer might give in a bit where it meets the frame etc.

    Give all that a go and report back.

    Edit - just seen the reply above. This could be a beginner's Doh moment, schoolboy error territory. :)
  • Hi everyone thanks for all the brilliant advice. Unfortunately due to work unforeseen work commitments I now will not have time to tinker until Saturday.

    I will follow all your advice and report back on the end result.

    Cheers
  • i had exactly the same problem as this and what you are describing. After messing about with the cable, the barrel adjusters, the mech itself and just about everything else related to the front mech not shifting right and the cable going 'loose' as you describe, it turned out the shifter was f*cked.

    You would never have known it, as it still shifted up and down but the inners weren't working properly. Sent to LBS, new shifter fitted and everything was fine. This was on a Tiagra shifter as well.

    I hope this isn't your problem as the shifter cost is a lot more than a cable.
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