rear derailleur adjustment

Discussion in 'Cycling Equipment' started by flyingdutch, Jan 26, 2005.

  1. flyingdutch

    flyingdutch New Member

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    OK, Im sure this has been asked (or similar) a zillion times but searchig hasnt fixed me up

    I hav recently changed cassettes and in the process my indexing at the rear has gone awol.

    I have set the H+Lscrews as accurately as i can, by my guesstimates :rolleyes: and the shifting is generally 'OK' but on the inner/larger cogs its innacurate.
    I can shift up onto the largest one no probs, but going back to the smaller ones it seems to need more left-to-right movement of the derailleur.
    ie from 26-to-23 its not going far enuff to sit on the 23 cleanly ,etc. this applies down to the 21 (or 19. i cant remember accurately...)
    Im wondering if my Lscrew is allowing the inside (ie big cog) too much tolerance???

    fanx in advance
     
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  2. flyingdutch wrote:
    > OK, Im sure this has been asked (or similar) a zillion times but
    > searchig hasnt fixed me up
    >
    > I hav recently changed cassettes and in the process my indexing at the
    > rear has gone awol.
    >
    > I have set the H+Lscrews as accurately as i can, by my guesstimates
    > :rolleyes: and the shifting is generally 'OK' but on the inner/larger
    > cogs its innacurate.
    > I can shift up onto the largest one no probs, but going back to the
    > smaller ones it seems to need more left-to-right movement of the
    > derailleur.
    > ie from 26-to-23 its not going far enuff to sit on the 23 cleanly ,etc.
    > this applies down to the 21 (or 19. i cant remember accurately...)
    > Im wondering if my Lscrew is allowing the inside (ie big cog) too much
    > tolerance???


    Those screws only set the limits of travel.

    If the "L" screw is too tight, the only result will be difficulty
    shifting onto the biggest sprocket. If it's too loose, the chain might
    overshoot and the derailer go into the spokes.

    Difficulty shifting to smaller sprockets is usually caused by cable
    friction, or possibly by incorrect indexing adjustment (that's the
    adjusting barrel where the cable housing contacts the rear derailer.)

    For more detailed instructions, see:

    http://sheldonbrown.com/derailer-adjustment

    Sheldon "http://sheldonbrown.com/derailer-adjustment" Brown
    +-----------------------------------------+
    | He not busy being born is busy dying. |
    | -Bob Dylan |
    +-----------------------------------------+
    Harris Cyclery, West Newton, Massachusetts
    Phone 617-244-9772 FAX 617-244-1041
    http://harriscyclery.com
    Hard-to-find parts shipped Worldwide
    http://captainbike.com http://sheldonbrown.com
     
  3. flyingdutch

    flyingdutch New Member

    Joined:
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    suspected as much and from what I had read it did seem that way but just wanted confirmation. Neveer thought I would get a reply from someone as noble as yerself tho :)

    cheers for that. Oh well, more shed time for me. not that one needs an excuse, mind :rolleyes:
     
  4. A Muzi

    A Muzi Guest

    flyingdutch wrote:
    > OK, Im sure this has been asked (or similar) a zillion times but
    > searchig hasnt fixed me up
    >
    > I hav recently changed cassettes and in the process my indexing at the
    > rear has gone awol.
    >
    > I have set the H+Lscrews as accurately as i can, by my guesstimates
    > :rolleyes: and the shifting is generally 'OK' but on the inner/larger
    > cogs its innacurate.
    > I can shift up onto the largest one no probs, but going back to the
    > smaller ones it seems to need more left-to-right movement of the
    > derailleur.
    > ie from 26-to-23 its not going far enuff to sit on the 23 cleanly ,etc.
    > this applies down to the 21 (or 19. i cant remember accurately...)
    > Im wondering if my Lscrew is allowing the inside (ie big cog) too much
    > tolerance???
    >
    > fanx in advance
    >
    >

    It's not yet spring but a good time to review basic gear
    adjustments. Take a peek at Sheldon Brown's excellent pages
    or any number of other resources.

    What you want to do is check the _system_ rather than turn a
    screw. That's a major turning point here in the development
    of a new mechanic - and we've trained our fair share over
    the years. A couple of minutes' observation saves time and
    frustration. Don't pick up that screwdriver yet.

    Check your chain wear. Is it the chain sticky with crud?
    Lubricated? Does the hub bearing have excessive play? Are
    the cassette cogs loose on the cassette body?

    Undo the cable (Shift rear to low. Stop pedaling. Return
    the lever to high. Slip a casing out of its stop). Pedal
    and let the changer return to high gear. (unscrew the H
    screw if it doesn't go) Get your head behind the changer and
    look at the cage. Is it roughly parallel to the chainrings?
    Are there cement marks on the outside edges of the changer?
    Do the pivot springs both return snappily? Will the body
    itself return easily to high gear? Check that by shifting
    with your hand.

    Place the first two fingers of your left hand behind the
    adjuster. Press the right side of the nameplate with your
    thumb while pedaling with your right hand. Let go and keep
    pedaling. It should return smartly to high gear.

    Now do that firmly for low gear. Make sure the changer
    doesn't sail off beyond low gear into the spokes.

    Slide the casing along the wire. Is is free? Is the end
    ferrule kinked? Crud on the BB guide? For integrated
    levers, does the wire move easily in the top casing? Pull
    the wire with one hand while shifting with the other. For
    any casing, pull the wire out, wipe any crud, look for rust
    or kinks. Lubricate the wire where it will go in casing.
    (We use Rock-N-Roll for nicer modern teflon lined cables,
    oil on Huffys).

    My point is that the vagaries of actually using your bike
    make small degradations that add up. Once in a while you
    ought to review the whole system before turning that screw.

    --
    Andrew Muzi
    www.yellowjersey.org
    Open every day since 1 April, 1971
     
  5. tommie

    tommie Guest

    flyingdutch wrote:
    > OK, Im sure this has been asked (or similar) a zillion times but
    > searchig hasnt fixed me up
    >
    > I hav recently changed cassettes and in the process my indexing at

    the
    > rear has gone awol.
    >
    > I have set the H+Lscrews as accurately as i can, by my guesstimates
    > :rolleyes: and the shifting is generally 'OK' but on the inner/larger
    > cogs its innacurate.
    > I can shift up onto the largest one no probs, but going back to the
    > smaller ones it seems to need more left-to-right movement of the
    > derailleur.
    > ie from 26-to-23 its not going far enuff to sit on the 23 cleanly

    ,etc.
    > this applies down to the 21 (or 19. i cant remember accurately...)
    > Im wondering if my Lscrew is allowing the inside (ie big cog) too

    much
    > tolerance???
    >
    > fanx in advance
    >
    >
    > --
    > flyingdutch



    There's great articles on adjusting derailleurs and everything else
    bike related at Park Tool's website:

    http://www.parktool.com/repair_help/FAQindex.shtml

    Just click on the part of the bike you're interested in and it will
    take you to the relevant articles.

    This site has helped me where other sources of information have failed,
    including repair books that I've bought.

    Good luck!

    -tom
     
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