derailleur trouble

Discussion in 'General Cycling' started by Julian Bradfield, Sep 20, 2011.

  1. Different derailleur trouble: mine no longer shifts on to the smallest
    sprocket. This is not a big deal, since I have occasion to use it
    about once a year, but it's kind of annoying.
    It's not the limit screw; and it's not cable friction, as the cable is
    slack. Nor, as far as I can see, is the hanger bent.
    The cage can be moved outward by hand so as to engage the highest
    gear; but it doesn't seem to be able to do it under its own power.

    Suggestions? Just hopelessly gunged up?
    Julian Bradfield, Sep 20, 2011
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  2. Julian Bradfield

    nmm1 Guest

    Or leverage loss, due to wear, weakening springs or whatever.
    In my limited experience with those horrors, this is very common,
    and damn-near unfixable. I have had several in my hands which
    got to a state that you just couldn't adjust them so they would
    change to all sprockets when actually used, and so had to give
    up on one or the other end.

    Nick Maclaren.
    nmm1, Sep 20, 2011
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  3. Julian Bradfield

    Phil W Lee Guest

    I think you already nailed it.
    Clean it thoroughly, removing it to soak in paraffin if that is what
    it takes to get all the gunge out.
    Lubricate with a drop of motor oil at every pivot point to avoid it
    jamming up again, and it's worth making a brief excursion to the
    extreme gears (particularly the small sprocket and small chainring,
    although never at the same time) on every ride, just to stop it doing
    the same in the future.

    The smallest sprocket (on both ends) is the one that is moved towards
    entirely by spring tension, so is the easiest to lose - going to a
    larger sprocket (or chainring) is by pulling the cable, so it's easier
    to overcome a little resistance.
    Phil W Lee, Sep 21, 2011
  4. Julian Bradfield

    Tim Downie Guest

    Gunge gets my vote. ;-)

    Tim Downie, Sep 21, 2011
  5. Julian Bradfield

    nmm1 Guest

    Whether or not it is the most likely solution, it is the first
    thing to try. If the problem is wear or weakening, then the only
    solution is to replace everything (or live without that gear).
    Yes, start by degunging.

    Nick Maclaren.
    nmm1, Sep 21, 2011
  6. Julian Bradfield

    Rob Morley Guest

    Probably gunge, sloppy chain, sloppy joints. Clean it thoroughly, oil
    pivoting and sliding surfaces and check where the spring bears on the
    body. Once it's clean and there's no obvious sticking point, if it
    still won't shift properly you'll need to replace the mech and/or the
    chain, and probably the cable for good measure.
    Rob Morley, Sep 21, 2011
  7. Julian Bradfield

    thirty-six Guest

    Probably. The otherwise useless can of WD40 (Xmas)comes into its own
    here. Be generous with it to blast out the muck and thickened oil.
    If it dpoesn't free up in ten minutes, leave it till tomorrow and try
    again, then re-check the cable in detail.
    thirty-six, Sep 21, 2011
  8. Julian Bradfield

    Ron Lowe Guest

    Cable tension from the shifter pulls it up the way, and the spring pulls
    it backdown.

    If the spring can't pull it back, it's likely there's excessive friction
    from a gummed-up mechanism, or excessive friction in the cable.

    If you've eliminated cable friction by disconnecting or slackening the
    cable, and backed off the limit screw, then all that remains is
    excessive friction in the mech itself. The fact you can push it out by
    hand supports this.

    I'd remove the mech entirely, and bathe it in a parts cleaner or diesel.
    Operate the mech by hand fully many times whilst submerged. Once
    it's operating smoothly, blast it dry with compressed air. Rinse and
    repeat if necessary. Finally, lubricate with a thin oil and operate
    the mech by hand to work the oil in to all the places it needs to be.

    If the mech remains stiff to operate after a thorough clean and lube,
    then it's goosed.
    Ron Lowe, Sep 21, 2011
  9. I had that - took ages of botching before I realised that the deraileur
    mech attachment wasn't tight to the tube and had been pulled down a bit.
    Esra Sdrawkcab, Sep 22, 2011
  10. Julian Bradfield

    al Mossah Guest

    I had a similar problem; couldn't get the smallest sprocket on the
    front mech. Checked end stop screws. Tried de-gunging. No change.
    I fixed it by loosening the whole mechanism and twisting it slightly
    so that the arm moved slightly further in. Had to make sure that it
    still moved far enough outwards to get the top gear OK.
    al Mossah, Sep 22, 2011
  11. Julian Bradfield

    Ian Smith Guest

    That's a handy tip, which I'll note for future reference. Mine had a
    similar issue, cured by tightening up the cable; it now just makes it
    across the 3 chainrings. However, it's been ages since I used the
    smallest; now somewhat redundant and looking rather clean these days. But
    like to keep it on there working, just in case I go for an epic ride at
    some point fully loaded up giant hills.
    Ian Smith, Sep 23, 2011
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