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  1. #1
    Member siovene's Avatar
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    Shimano Sora: trouble in the second cog of the front derailleur

    Hi,
    first of all, apologies if I use the wrong terminology at times: I'm new to bicycling.

    I have a Marin Fairfax with Sora derailleurs and shifters. I have 3 problems with it (in order of severity):

    1. When I'm in the second cog in the front derailleur, and in a cog smaller than the 4th in the rear one, the chain touches the front derailleur producing an annoying noise. The noise is increased if I do a heavy pedalling stroke with my right foot. I have made sure the derailleur is aligned to the 1st and 3rd cogs fine, by tuning the limit screws. How do I fix this problem? I have also tried to change the tension of the cable that runs from the shifter to the derailleur, by removing it from the derailleur side, shifting to the leftmost front and read cogs, and trying different initial tension: it took me a lot of trial and error to even get a setup that will allow me to shift to all 3 cogs, so I'm really afraid to tune that further.
    2. Shifting from a smaller to a larger cog in the front derailleur is really hard on my thumb. I have tried tuning the tension of the cable that runs from the shifter to the derailleur, but that will mess up the alignment between the derailleur and the cogs. Any solution or is Sora just that bad?
    3. When I'm in the 2nd cog of the front derailleur, and in the 5th smallest cog in the rear deraileur, one tooth of the 3rd cog of the front derailleur will grab one of the links in the chain, lift it just a little bit, but not enought for it to make the chain shift to the 3rd cog. Infact, the link is not grabbed from the inside of it, but from the side, where one of the link's components protudes slightly. That tooth in the cog doesn't seem to be bent.


    Thanks in advance for the help!

  2. #2
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    You need to fine tune the front derailleurs trim by adjusting the cable length more precisely. Threaded adjusting barrels like on the rear derailleur make this far easier than having to reposition the cable trial and error. If there isn't one on the cable stop, buy an inline adjuster like one of these (scroll down a bit). Once it's installed you'll be able to fine tune the FD trim the same way you do the rear.

    Your problem having to force the shift to the big ring might be beacuse you have the limit set a bit tight, or might be because you're not easing up the pedaling force enough. Unlike the rear, front derailleur operates on the tight side of the chain, so while you're trying to lift it to the large ring with the shifter, the tension from pedal force is trying to pull it down.

    Lastly, while some Shimano FD shift levers have the ability to slightly adjust the trim of the FD cage in response to the changing chain angle coming from the cassette, I don't think Sora's have that feature (someone who's more familiar with Sora, please confirm or correct me here). That means that you'll have to fine tune for the best position of the FD cage that doesn't rub on when your using the rear sprockets you most often use, and live with some rubbing when coming from more extreme angles.

    But step one on the way to solving the problem is the inline adjuster so you can adjust trim precisely.
    Last edited by FBinNY; 08-10-10 at 04:45 AM.
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  3. #3
    Member siovene's Avatar
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    Hi,

    Quote Originally Posted by FBinNY View Post
    You need to fine tune the front derailleurs trim by adjusting the cable length more precisely. Threaded adjusting barrels like on the rear derailleur make this far easier than having to reposition the cable trial and error. If there isn't one on the cable stop, buy an inline adjuster like one of these (scroll down a bit). Once it's installed you'll be able to fine tune the FD trim the same way you do the rear.
    There is one at the cable stop. It's really hard to screw/unscrew, and after my fingers started to hurt I had to resort to using pliers to tune it. Still I'm not sure it works, because I can't see anything happening on the other end. Could it be that the tension of the cable is so bad that the barrel won't work? I doubt, because the derailleur works okayish, besides the problems I posted.

    Your problem having to force the shift to the big ring might be beacuse you have the limit set a bit tight
    Not into the big ring only, but to any bigger ring, i.e. from 1 to 2 and from 2 to 3.

    , or might be because you're not easing up the pedaling force enough.
    I've tried various pedaling speeds and techniques, and even not pedaling: the thumb shifter is always as hard to push.

  4. #4
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    Test that the barrel adjuster is OK by putting the FD into the middle position, and turning the adjuster. As you turn the barrel out, the FD should move outward. If it doesn't respond, the adjuster isn't working. Possibly it's so hard to turn for a reason, and you need to figure out why, or just go ignore it and add an inline adjuster.

    As for the thumb shifter. It might just be a characteristic of the lever, or there might be extra friction in the cables. When you take the cable off to work on the adjuster, test the thumb shifter applying light tension on the cable with your hand. If it's still hard, then it's just the way it is and is another thing to live with.
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  5. #5
    Member siovene's Avatar
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    Quote Originally Posted by FBinNY View Post
    Test that the barrel adjuster is OK by putting the FD into the middle position, and turning the adjuster. As you turn the barrel out, the FD should move outward. If it doesn't respond, the adjuster isn't working. Possibly it's so hard to turn for a reason, and you need to figure out why, or just go ignore it and add an inline adjuster.
    Ok great, I'll try to figure out if it really doesn't work.

    As for the thumb shifter. It might just be a characteristic of the lever, or there might be extra friction in the cables. When you take the cable off to work on the adjuster, test the thumb shifter applying light tension on the cable with your hand. If it's still hard, then it's just the way it is and is another thing to live with.
    It's not hard at all if I release the cable. So it's hard just because the cable is pulling too much.

  6. #6
    Member siovene's Avatar
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    Hey FBinNY, a quick update: I think I've solved most of the problems. I've managed to play with the barrel adjuster near the shifter, and I got the front derailleur tuned fine I've also greased the chain and let the grease spread thru all cogs, so now it's considerably quieter. Also the thumb shifting is not so hard anymore, so I can live with it (I guess Sora is Sora...).
    I guess the only problem left is that some of the smaller cogs in the rear derailleur sometimes pick a chain link from the side, lifting it a little bit and producing some irregularities in the motion. Do you think some cog teeth might be bent? I crashed once but nothing bad.
    Anyway, thanks for the help!

  7. #7
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    If you mean the toothed idlers on the RD, that's a chainline issue, and not easily solved. Sometimes tweaking the cage slightly helps, but I don't suggest you try unless you're very comfortable with your skills.

    If you mean the smaller rear sprockets, where the chain does abortive shifts to the next larger one, that's usually a trim issue. Try adjusting the RD trim outboard a hair (1/8 turn in on the barrel) and try to find the sweet spot with food shifting both up and down without that problem. If you can't dial it in, it's very possible that the hanger isn't aligned perfectly, which is easy to correct but you'll need a $40 tool.
    FB
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    An ounce of diagnosis is worth a pound of cure.

    “Never argue with an idiot. He will only bring you down to his level and beat you with experience.”, George Carlin

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