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  1. #1
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    Advice Needed on Chainring rubbing chainstay on MCR

    I just built up my second MCR. I shoud have never sold the first one. Anyway, I am running a 1x9 with a 34 tooth chainring on an LX crank with an external bottom bracket. On my first ride I got some major chainring rubbing on the chainstay when I hit a root at a bit of an angle. I am wondering if running the 34 tooth in the middle ring position should not be done and I should be running it where the big ring would normally go. I do have the bottom bracket set up correctly with one large spacer on the drive side and no spacer on the non drive side since it is a 73mm bottom bracket shell. My concern is that my chainline will be more sever when I need to get up in the 34 in back on a climb.

    Has anyone else experienced this issue? I remember it happening on my last MCR as well. With full gear I weigh 180 and I am sure that makes some difference in the amount of flex I will get out of the chainstay and bottom bracket area.

  2. #2
    Zak
    Zak is offline
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    Weird - I run a 36T 1x9 with FSA K-Force cranks on mine and don't get any rubbing (I'm about 160 without gear). Instead of spacing it out, you could maybe run your ring on the outer mounts and move the spacer to the non-drive side.

  3. #3
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    Quote Originally Posted by Zak
    Weird - I run a 36T 1x9 with FSA K-Force cranks on mine and don't get any rubbing (I'm about 160 without gear). Instead of spacing it out, you could maybe run your ring on the outer mounts and move the spacer to the non-drive side.
    I am amazed you can run a 36 in the middle position. I wonder if on the FSA K-Force the middle position sits further out.

    I went over my bottom bracket setup again and the MCR is a 73mm shell so I used on spacer(the larger one) on the drive side and no spacer on the non drive side as the instructions showed. I moved my ring to the outer position but it makes for a pretty nasty chainline compared to in the middle position when I am in the 34 in the back.

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