Problem with shifting gears

Discussion in 'Cycling Equipment' started by mbabramo, Aug 1, 2007.

  1. mbabramo

    mbabramo New Member

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    This is something of a newbie question, so apologies, and thanks in advance for any help you can give!

    I recently decided to try to bike to work, and so I bought a used bike cheaply (a 21-speed Bianchi). One of the gear shifts was broken, and so I brought it to a bike shop, and they changed the gear shifts, and then told me I also needed a new back derailler, new pedals, and a new housing for the chain.

    Since getting the repaired bike (and paying over $200), I have frequently (every twenty minutes or so) had the problem that the chain would fall off. I tried to make little adjustments to the screws on the derailleurs, but I kept having the problem. I took it back to the bike shop that made the initial repairs, and they made some further adjustments, but then I still had the same problems. The repairman then told me that I was probably applying the wrong pedaling technique, and pushing too hard while changing gears (downshifting from 2 to 1 on the front gears).

    That helped to some extent, but even when I'm focused on being fairly gentle in pedaling while shifting gears, I've had the chain fall off occasionally. This happens especially if I'm going very slowly (for example, because I have to make a sharp 180 degree turn at the bottom of a hill). Sometimes, I find it hard to pedal as gently as necessary while shifting gears, because I'm trying to push my way up a hill.

    I should also note that sometimes changing gears doesn't seem to take. If I'm upshifting from 1 to 2, this isn't a big problem -- I just push a little bit harder and then it works. But when I'm downshifting from 2 to 1, it's quite annoying when the gear stays in 2 -- and then I have to try shifting back to 2 and then trying again.

    So, now I'm trying to figure out what to do. Should I (1) replace the front derailleur (will that better tolerate pushing on the pedals with some strength while downshifting?); (2) replace something else; (3) get a new bike; or (4) learn to deal with it and improve my technique.

    Underlying all these questions is the broader question of whether one should have to pedal especially gently to avoid having the chain come off. I used to have another bike some years ago and never had the chain fell off, but I suppose that my gear shifting technique might have deteriorated. On the other hand, it seems to me that a well-made bike should be somewhat tolerant of my pushing hard on the pedal.
     
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  2. Scotty_Dog

    Scotty_Dog New Member

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  3. mbabramo

    mbabramo New Member

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    Hi Scotty_Dog,

    I actually tried that, and then the bike shop tried to do that for me too, but I'm still having problems. I suppose it's possible that we just haven't made the adjustment correctly. Is it also possible that a derailleur might not be working well?

    --Michael
     
  4. Scotty_Dog

    Scotty_Dog New Member

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    It could be many things:
    you're shifting incorrectly
    worn shift cable
    worn shift cable housing
    badly positioned derailleur
    damaged derailleur
    stretched chain
    worn chainrings
     
  5. alfeng

    alfeng Well-Known Member

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    Did the shop replace BOTH shifters?

    Most of your shifting problems will be eliminated if you switch from Shimano shifters (which I presume you have) to Campagnolo shifters (despite what some people think/say/write, there really is a mechanical difference!) -- Campagnolo shifters can be used with Shimano derailleurs ...

    While unlikely, if (by chance) the shop installed Campagnolo shifters, then there may be a "systemic" problem -- e.g., the BB spindle is too long for the crank, the rear derailleur hanger is out of alignment, etc.



    BTW. Regardless, when there is a problem shifting in the FRONT of a Shimano drivetrain, it is more than likely the result of mis-matching the chain with the front derailleur, or vice-versa. Remember this:
    The rear cassette dictates the chain type, and the chain type dictates the front derailleur.
    That is, your current chain may be TOO NARROW (there is a seemingly insiginficant difference of about 0.1mm which does matter) for the front derailleur cage.
     
  6. kdelong

    kdelong Well-Known Member

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    +1 to alfeng's post. Take it to a different LBS, preferrably one that is reputable.
     
  7. mbabramo

    mbabramo New Member

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    Thanks for all the advice. It sounds like it could be any number of things. It actually is a pretty reputable bike shop, but maybe I should try another one (although I'm still trying to decide whether to just cut my losses).
     
  8. dabac

    dabac Well-Known Member

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    So you have a triple front and a 7 rear.

    ? Chain guard? That's not something you really "need", and it's quite rare to find on bikes running triple fronts, unless it's only a simple collar bolted to the biggest ring.

    What sprocket are you using on the rear when you're doing this?
    Remember that on a bike with a triple front you shouldn't be using ALL combinations. You should only use the full range at the rear while you're on the middle front. Small-small and big-big is a bad idea that increases wear and reduces performance. It's called cross chaining and is usually frowned upon.
    Going easy on the pedal while shifting gears is a good habit that reduces wear and helps maintain smooth action. A good RD will shift even under considerble load, but that one is working on the low tensioned part of the chain.
    As far as possible you should try to plan your riding so that you're in the right (front) gear already when you reach the obstacle, to avoid having to shift under load.

    The FD is working on the tensioned part of the chain, and even a high end FD is likely to stumble if you're trying to change under full load. Upshifting is probably done under less tension than downshifting, hence less trouble.

    It sure sounds like you're using your 1(smallest front) a lot, that one is often called the granny gear and usually don't see much use in ordinary road riding.

    IMO all FDs struggles to some degree to change gear under high load, so it's uncertain that you'll get your money's worth of improvement from a FD change. Cheaper and probably more efficient to learn to plan your riding/ reduce load to allow the FD to do its job under less strain. Done right it should only take fractions of a second for the chain to settle on a smaller front gear.

    If you are in the right gear at the rear and still find that you need to drop into the 1 in front that often you might consider another(bigger) rear cluster that'll give you lighter gear while staying in 2nd front.
    Also pay some attention to your shifting style. Many shifters can overshoot a little if nudged beyond the intended position. They'll spring back to the indexed position, thus removing all the evidence of having moved past the mark.

    That it should.
     
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