Can't shift to the small chainring
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  1. #1
    i like whiskey
    Reputation: innergel's Avatar
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    Jun 2002
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    Can't shift to the small chainring

    I was cleaning and tuning my wife's bike last night and she casually mentioned that she could not shift to her smallest chainring. I asked how long it has been like this, and she said "a long time". Lovely. Anyway, she has a Tiagra/105 triple on her Specialized Allez. So I pulled out my Zinn book and tried to fix the problem. Thirty minutes later, I still could not get the thing to shift to the small chainring. I tried everything from adjusting the high/low settings to adjusting the cable tension to actually removing, relubing and reinstalling the shift cable with no luck. The rest of the drive train shifts fine, so it's very odd this does not work.

    When I try to shift down, the cable is totally slack and the derailler moves down, just not far enough. It moves and shifts up to the other two just fine. I tried every adjustment Leonard Zinn suggested with no luck. Is it possible that the derailler is bent, or that there is some internal spring-type mechanism that is bound up or dirty or something?

    Help! I'm stumped.

  2. #2

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    Go all the way back to the default mode.

    STI triples can be a "bear" to get adjusted right. I've had the best results by starting over from the very beginning. I think that most guys try to skip steps and consequently pile one misadjustment onto another until the derailleur is completely fubarred. Try this:

    1. Disconnect the shift cable (important).
    2. Adjust the position of the derailleur on the seat tube. The outer cage should be parallel to the big chainring and should miss the big chainring by 2mm when you push it with your finger.
    3. Set the low gear limit screw. With the chain on the small ring in front and the biggest cog in back, the inner derailleur cage should miss the chain by about 1mm.
    4. Make sure your shifter is in the lowest gear position.
    5. Pull the cable taut with a needlenose plier and anchor it to the derailleur. Be sure that you go around the fixing bolt the correct way.
    6. Adjust the cable tension so that you can access all of the gear combinations. If you are still having trouble, recheck the above starting with 1.
    7. Adjust the high gear limit screw. With the chain on the biggest chainring and the smallest cog in back, the outer cage should miss the chain by about 1mm.

  3. #3
    Zeppelin/Ultegra Rider
    Reputation: 4bykn's Avatar
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    Jan 2001
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    930
    A possibility:

    I once had this same problem. Shifting toward the big ring was fine, but going the other way would inly go so far and stop. I finally found a small stone covered with tar stuck in the front derailleur, between the adjustment screw and its stop. I had to pick it otu, and flush the tar away with WD-40.
    Ride in Peace....Enjoy every sandwich......Mike

  4. #4

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    Mar 2002
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    I don't remember what model Specialized, but last year working at a shop, there was always a problem with small sized specialized aluminum frames & adjusting the front derailleur to shift to the inner ring on a triple. The front der would hit the seat tube before it had shifted into the inner cog. A quick fix is to slightly turn the fron of the der inward to push the chain in quicker. Umfortunately, this will usually cause more chain rub when shifting thru the rear gears. The other possibility is a slightly longer bottom bracket.

    Hopefull Spoke Wrench's idea works.

    JimPz

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