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Adjusting front mech

Started by Mark · · Last activity · 10 posts · 438 views

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UK and Europe
Published
21 August 2006
Last activity
22 August 2006
Original author
Mark
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10
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  1. Hi All,

    I seem to be having real problems adjusting the front mech on a Trek
    Hybrid. It changes up fine all the time and it changes down from the
    middle to the smallest chainring fine. However sometimes it does not
    change very well from the biggest chainring down to the middle.

    The problem is not consistent, sometimes it works fine. I have had
    many goes at trying to adjust it and I just can't get it right. I even
    took it to the bike shop but they could not get it any better.

    It's a Shimano Altus, about 8 years old. The bike does not get heavy
    use. Can anyone give me some clues on how to get this working?

    TIA, Mark

  2. Mark said:

    Hi All,

    I seem to be having real problems adjusting the front mech on a Trek
    Hybrid. It changes up fine all the time and it changes down from the
    middle to the smallest chainring fine. However sometimes it does not
    change very well from the biggest chainring down to the middle.

    The problem is not consistent, sometimes it works fine. I have had
    many goes at trying to adjust it and I just can't get it right. I even
    took it to the bike shop but they could not get it any better.

    It's a Shimano Altus, about 8 years old. The bike does not get heavy
    use. Can anyone give me some clues on how to get this working?

    Given the age and the symptoms, have you tried replacing the cable?

    Tim

  3. Tim Hall said:
    Mark said:

    Hi All,

    I seem to be having real problems adjusting the front mech on a Trek
    Hybrid. It changes up fine all the time and it changes down from the
    middle to the smallest chainring fine. However sometimes it does not
    change very well from the biggest chainring down to the middle.

    The problem is not consistent, sometimes it works fine. I have had
    many goes at trying to adjust it and I just can't get it right. I even
    took it to the bike shop but they could not get it any better.

    It's a Shimano Altus, about 8 years old. The bike does not get heavy
    use. Can anyone give me some clues on how to get this working?

    Given the age and the symptoms, have you tried replacing the cable?

    Not yet. Out of interest, why would replacing the cable help in this
    case?

    Thanks, Mark

  4. Mark said:
    Tim Hall said:
    Mark said:

    Hi All,

    I seem to be having real problems adjusting the front mech on a Trek
    Hybrid. It changes up fine all the time and it changes down from the
    middle to the smallest chainring fine. However sometimes it does not
    change very well from the biggest chainring down to the middle.

    The problem is not consistent, sometimes it works fine. I have had
    many goes at trying to adjust it and I just can't get it right. I even
    took it to the bike shop but they could not get it any better.

    It's a Shimano Altus, about 8 years old. The bike does not get heavy
    use. Can anyone give me some clues on how to get this working?

    Given the age and the symptoms, have you tried replacing the cable?

    Not yet. Out of interest, why would replacing the cable help in this
    case?


    OK, I'd assumed the cable is running through a bit of flexible housing
    _somewhere_ along its route. Cables/housings get skanky, full of crud
    or the inner to the housing breaks down over time. All these introduce
    a (variable) amount of friction into the system. Shifting one way is
    done using muscle power, which can over come that friction quite
    easily. Shifting the other way is done by you slacking off the cable
    and a spring doing the work. This has a harder time overcoming the
    friction.

    If it doesn't run through a bit of flexible housing then it's likely
    to be a different problem.

    Tim

  5. Tim Hall said:
    Mark said:

    Not yet. Out of interest, why would replacing the cable help in this
    case?


    OK, I'd assumed the cable is running through a bit of flexible housing
    _somewhere_ along its route. Cables/housings get skanky, full of crud
    or the inner to the housing breaks down over time. All these introduce
    a (variable) amount of friction into the system. Shifting one way is
    done using muscle power, which can over come that friction quite
    easily. Shifting the other way is done by you slacking off the cable
    and a spring doing the work. This has a harder time overcoming the
    friction.

    If it doesn't run through a bit of flexible housing then it's likely
    to be a different problem.

    OK. Thanks a lot for the explanation. It does run through flexible
    housing for some of its length.

    Cheers, Mark

  6. Tim Hall said:
    Mark said:

    Hi All,

    I seem to be having real problems adjusting the front mech on a Trek
    Hybrid. It changes up fine all the time and it changes down from the
    middle to the smallest chainring fine. However sometimes it does not
    change very well from the biggest chainring down to the middle.

    The problem is not consistent, sometimes it works fine. I have had
    many goes at trying to adjust it and I just can't get it right. I
    even took it to the bike shop but they could not get it any better.

    It's a Shimano Altus, about 8 years old. The bike does not get heavy
    use. Can anyone give me some clues on how to get this working?

    Given the age and the symptoms, have you tried replacing the cable?

    Other possible at the age is the pivots in the changer are loose. Check by
    just feeling the cage; if its a bit loose and twisty on the pivots then its
    worn. The pivots are not replaceable as far as I can see (and I usually
    service things which are officially not serviceable), so its a new
    mechanism.

    I recently changed the front mech on my partner's bike. About 8 years old,
    and, I think Alivio. New changer (Deore I think, cost about £20) is a lot
    more positive about shifting.

    - Nigel

    --
    Nigel Cliffe,
    Webmaster at http://www.2mm.org.uk/

  7. "Mark" <[email hidden]> wrote in message
    news:[email hidden]...

    Quoted message said:

    Hi All,

    I seem to be having real problems adjusting the front mech on a Trek
    Hybrid. It changes up fine all the time and it changes down from the
    middle to the smallest chainring fine. However sometimes it does not
    change very well from the biggest chainring down to the middle.

    The problem is not consistent, sometimes it works fine. I have had
    many goes at trying to adjust it and I just can't get it right. I even
    took it to the bike shop but they could not get it any better.

    It's a Shimano Altus, about 8 years old. The bike does not get heavy
    use. Can anyone give me some clues on how to get this working?

    Is it one of the trendy new style ones? I.E. Top swing? I had one that could
    never be adjusted to work reliably. I'd swap it for a bottom swing Deore.

  8. Mark said:
    Quoted message said:

    On Mon, 21 Aug 2006 14:03:03 +0100, Mark <[email hidden]> wrote:


    OK. Thanks a lot for the explanation. It does run through flexible
    housing for some of its length.

    I've looked more carefully at this and it only runs a short length
    through housing (from gear change selector to top of frame).
    Anyway I can't figure out how to remove the cable from the selector.
    In the past there was a slot and a hole to remove cables from but I
    can see nothing like that on these gear selectors (two lever type).
    Is there some magic here? There is a small screw, which I removed but
    that did not appear to do anything.

    I did lubricate the cable (which looks in good condition btw) but I
    don't think it has made any difference. I'll need to ride a bit
    further before I can really be sure.

    Strangely the gear change has always worked perfectly when the bike is
    upside down but when I actually ride it the front gear change behaves
    differently.

    Cheers, Mark

  9. On Mon, 21 Aug 2006 16:39:03 +0100, "Nigel Cliffe" <[email hidden]>

    Quoted message said:

    Tim Hall wrote:
    Other possible at the age is the pivots in the changer are loose. Check by
    just feeling the cage; if its a bit loose and twisty on the pivots then its
    worn. The pivots are not replaceable as far as I can see (and I usually
    service things which are officially not serviceable), so its a new
    mechanism.

    Thanks for the advice. I'll try this. One thing I have only just
    noticed is that the cage does not look right. At the front it is
    really close to the large ring, but at the bottom it is more than 1cm
    away. Is this likely to cause a problem?

    Quoted message said:

    I recently changed the front mech on my partner's bike. About 8 years old,
    and, I think Alivio. New changer (Deore I think, cost about £20) is a lot
    more positive about shifting.

    If I had any money I would buy a new bike ;-) The trek was only
    supposed to be a stop-gap bike for commuting pending an insurance
    claim. I only got pennies so I am still riding the trek 8 years later
    :-(

    However it might be worth upgrading the components since most of them
    are fairly worn anyway. I was looking at the sprocket teeth and I'm
    not sure that some of them are starting to look bad.

    Cheers, Mark

  10. Doki said:


    "Mark" <[email hidden]> wrote in message
    news:[email hidden]...

    Quoted message said:

    Hi All,

    I seem to be having real problems adjusting the front mech on a Trek
    Hybrid. It changes up fine all the time and it changes down from the
    middle to the smallest chainring fine. However sometimes it does not
    change very well from the biggest chainring down to the middle.

    The problem is not consistent, sometimes it works fine. I have had
    many goes at trying to adjust it and I just can't get it right. I even
    took it to the bike shop but they could not get it any better.

    It's a Shimano Altus, about 8 years old. The bike does not get heavy
    use. Can anyone give me some clues on how to get this working?

    Is it one of the trendy new style ones? I.E. Top swing? I had one that could
    never be adjusted to work reliably. I'd swap it for a bottom swing Deore.

    I doubt anything on the bike is trendy :-) It was the cheapest bike I
    could buy at the time. I'm not sure what "top swing" is. If you mean
    the cable routing then it is routed under the bottom bracket.

    Mark

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