Chain and chain rings
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  1. #1
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    Chain and chain rings

    Is it ok to run the chain in the 39 in the front and the 11 in the back? My LBS says its not a good idea. I've never heard of this. Mine rubs, thats why I'm asking. Either they can't fix it or I'm in the wrong and shouldn't ride it there.

  2. #2
    RoadBikeRider
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    I am assuming you are running a double crank, not a triple. What you explain is the most extreme case of "cross chaining" and normally not considered to be a good idea. Puts the chain at a big angle and exerts excessive force on it and other driveline parts. It is also very difficult if not impossible to tune out all the rub in that gear combination. By the time you are in that combination you should probably be in the big ring up front. I try to avoid the 2-3 smallest cogs when in the small ring up front.

  3. #3
    wim
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    Even if it rubs, nothing wrong with running the 39 x 11 for a few seconds or so if you're going to shift back to your larger cogs. But often, running a 39 x11 means that it's time to go to the big ring. The equivalent gear of 53 x 15 is easier on the drive train, plus you got a few more cogs to shift into should the ride get even faster.

    If you have short chainstays, you might have to live with a rub on the inside of the big chainring. I never minded it on one of my bikes—considered it an audible warning to go to the big ring soon. If your rub is on the front derailleur cage only, it's an easy fix.
    Last edited by wim; 09-12-2008 at 05:11 AM.

  4. #4
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    When you ride around in the 39 X 11, people will think that you are a noob.
    If your opinion differs from mine, ..........Too bad.
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  5. #5
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    And you do realize that those cross-chain gears are usually a virtual duplication of other combinations that don't have the cross-chaining problem? As wim noted, 52X15 gives you almost the same gear ratio (only 2% difference) as your 39x11. And 39x12 is exactly the same as 52x16. So you don't really need to use those combinations.

  6. #6
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    Besides that, little rings are for sissies. They should only be used when there aren't other riders around to laugh at you, for your sissyness.
    If your opinion differs from mine, ..........Too bad.
    .
    How would you like it if Hitler killed you
    Dogbert.

    I>U

    Buying parts to hang on your bike is always easier than getting fit.

    If you feel wimpy and weak, get out and train more, ya wee lassie!

    If Jesus had a gun, he'd be alive today!

  7. #7
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    Understanding the issue

    Quote Originally Posted by Dank
    Is it ok to run the chain in the 39 in the front and the 11 in the back? My LBS says its not a good idea. I've never heard of this. Mine rubs, thats why I'm asking. Either they can't fix it or I'm in the wrong and shouldn't ride it there.
    You cannot adjust the rub out of this arrangement without messing up the chain line by shifting the crank set too far to the right. The chain is rubbing against the large chainring, even if it is not rubbing against the front derailleur cage. The chain is made of hardened steel, while the chainring is made of aluminum. Just how long do you think the chainring will last? You are "in the wrong" and shouldn't ride it there.

  8. #8
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    Quote Originally Posted by MR_GRUMPY
    Besides that, little rings are for sissies. They should only be used when there aren't other riders around to laugh at you, for your sissyness.
    That's right. I ride a triple with 39, 52, and 66. And I ride in the 66 all the time, the other two gears are just for show. Of course my cassette runs from 25 to 42...

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