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  1. #1
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    Rear derailleur issue

    Hi,
    I have a new to me spare bike. It has a X9 mid cage rear derailleur. it was converted from 3x10 to 2x10 with 22/33/bash guard.
    When I'm in the small front ring and the smallest 3 rear rings, the chain rubs against itself at the rear derailleur due to lack of tension. The derailleur is basically flat at this point. I know this is a bad gear combo, but this doesn't happen on my other bikes. When I'm on the 33 tooth ring and the large rear cassette the rear derailleur is pulled a forward so I think I have the right chain length.
    I played with that tension adjustment screw (don't know the technical term) on the derailleur mount stop and that took out some of the slack but it didn't stop the rub.
    Going through the possibilities in my head:
    1-chain is too long
    2-mid cage derailleur dosn't take up as much slack as a long cage?? (never had one)
    3- bad derailleur
    All help is appreciated.

  2. #2
    Trail Tire TV on blogger
    Reputation: thomllama's Avatar
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    chain's too long.. but #2 also...

    Mid cage should never be used on a 3x drivetrain, Especially on a 10 speed setup that has a larger gear span. Thou some racer types like it for weight saving, they also are sensitive to what gear/combo they are in to avoid the issue... even thou you went down to 2x with the 10 speed the cage of the derail might not be long enough to suck up the slack... need to do the math.
    Going to try and bring Trail Tire TV back. go take a look... http://trailtiretv.blogspot.com/

  3. #3
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    Thanks, I'll shorten the chain. The drivetrain was converted to 2x10 with a 22/33 front ring setup and 11-36 rear cassette. Is a medium cage ok for 2x10?

  4. #4
    Trail Tire TV on blogger
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    Quote Originally Posted by dhelm72 View Post
    Thanks, I'll shorten the chain. The drivetrain was converted to 2x10 with a 22/33 front ring setup and 11-36 rear cassette. Is a medium cage ok for 2x10?
    it might be.. you have to do the Math.. basically the differance between large and small cassette plus the diff between the two up front... the total # added together.. then go to sram's site and see what the rear derail can suck up in the specs.

    here... 11-36 cassette = 25
    22-33 front = 11
    total 36..
    find the specs on your derail and make sure it'll eat up 36 .. thinking it doesn't (some reason I got 33 in my head for mid cage but I'm far from 100% on that)

    shorten the chain... actually.. measure it proper, wrap it around the large front and the large rear rings without going thru derails.. add 2 links.. that should be the chain length.
    Going to try and bring Trail Tire TV back. go take a look... http://trailtiretv.blogspot.com/

  5. #5
    Plays with tools
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    I wouldn't shorten the chain I would just stay out of your small/small. I completely condone cross chaining in the other direction and if shortening your chain will compromise that I say leave it as is.

  6. #6
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    Do what Thomllama said, for sure, but remember, if you have a full squish bike, you'll need to fully compress your rear suspension before sizing the chain. You may very well wind up, then, with a slightly droopy chain when the suspension is uncompressed in small-small, but once you sit on the bike, it should be fine (and you shouldn't be in that gear anyway).

  7. #7
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    Quote Originally Posted by thomllama View Post
    it might be.. you have to do the Math.. basically the differance between large and small cassette plus the diff between the two up front... the total # added together.. then go to sram's site and see what the rear derail can suck up in the specs.

    here... 11-36 cassette = 25
    22-33 front = 11
    total 36..
    find the specs on your derail and make sure it'll eat up 36 .. thinking it doesn't (some reason I got 33 in my head for mid cage but I'm far from 100% on that)

    shorten the chain... actually.. measure it proper, wrap it around the large front and the large rear rings without going thru derails.. add 2 links.. that should be the chain length.
    Does this method make the chain too shot to do big/big ring once you run it through the.derailleur?

  8. #8
    Trail Tire TV on blogger
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    Quote Originally Posted by dhelm72 View Post
    Does this method make the chain too shot to do big/big ring once you run it through the.derailleur?
    nope... as long as you add the 2 links .. the derail can be pulled out front and up.. as long as there is a "S" bend in the chain, you're good..
    Going to try and bring Trail Tire TV back. go take a look... http://trailtiretv.blogspot.com/

  9. #9
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    Quote Originally Posted by dhelm72 View Post
    Hi,
    I have a new to me spare bike. It has a X9 mid cage rear derailleur. it was converted from 3x10 to 2x10 with 22/33/bash guard.
    When I'm in the small front ring and the smallest 3 rear rings, the chain rubs against itself at the rear derailleur due to lack of tension. The derailleur is basically flat at this point. I know this is a bad gear combo, but this doesn't happen on my other bikes. When I'm on the 33 tooth ring and the large rear cassette the rear derailleur is pulled a forward so I think I have the right chain length.
    I played with that tension adjustment screw (don't know the technical term) on the derailleur mount stop and that took out some of the slack but it didn't stop the rub.
    Going through the possibilities in my head:
    1-chain is too long
    2-mid cage derailleur dosn't take up as much slack as a long cage?? (never had one)
    3- bad derailleur
    All help is appreciated.
    I just did this on my bike, converted 3x10 to 2x10 with bash, also switched to med cage derailleur. I was getting chain rub on the small ring. Here is what I did

    1) shortened the chain to reflect the decrease in ring sizing
    2) lowered the front derailleur to reflect the smaller "big" ring
    3) rotated it slightly so it didnt rub in any gear combo

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