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  1. #1
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    XX1 ChainRing vs Frame Clearance

    Hi,
    I set up 36T chain ring on the front and I'm little bit confused about clearance between frame and chain ring. It is only 2-3mm.. I'm not sure is it enough..
    What is your opinion?
    This is PF30..

    XX1 ChainRing vs Frame Clearance-zdj-cie.jpg

  2. #2
    Carbon & Ti rule
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    With the XX1 cranks the ring sits about were the middle ring would on a triple setup, so you would normally only have a 32 there & that is why there is so little room with your 36 ring.

    With the old style rear derailieur I would not run it like that, But with XX1 I would.

  3. #3
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    Thank you for your answer.
    Why rear derailleur has influence on it?

    I was thinking that lack of front derailler could be a reason to accept this.

    Bartek

  4. #4
    Carbon & Ti rule
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    Quote Originally Posted by bfigas View Post
    Thank you for your answer.
    Why rear derailleur has influence on it?

    I was thinking that lack of front derailler could be a reason to accept this.

    Bartek
    Because without a clutch type rear derailieur the chain could bounce up & jam between the ring & the frame & damage both.

    But with the clutch type it would be much harder for that to happen.

  5. #5
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    Ok, thank you.
    I was thinking also about stiffness of crankset. Can hard peddaling cause bending crankset? This why I wrote that I have PF30.

    Yesterday, I saw my friend frame with 3x9 system. He has a huge scratch (it is more like a ditch), 1-1.5mm deep and 3mm wide. It seems like something (chainring) regulary scratch the frame.
    I was wandering how was possible to make it...?? And his clearance is much much more bigger. The scratch is from 44T ring.

  6. #6
    Formerly of Kent
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    Think about where you apply the most force during the pedal stroke. Then, think about what that would do to the cranks and chainrings, if the right amount of force was applied.

    In short, your pedal stroke is NOT going to do anything to move the chain/chainring into a position where it might be making contact with the frame.

  7. #7
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    Bonking ... not feelin' well

    I had the same issue a few weeks ago. Got a Lynskey Pr650 Ti frame, Chris King GXP bottom bracket and with the XX1 36t installed there was only 1.5mm of clearance. I didn't think that was enough so I switched to 34t and returned the 36t Please tell me I did the right thing....

  8. #8
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    Le Duke,
    The biggest force is during pushing pedal forward. But there is additional force to the inside (centripetal).
    If the crankset and bottom bracket is not stiff enough it can cause shortening distance between frame and chain ring.

    Maybe I'm wrong, but I remember my first bicycle (many years ago) with shimano SIS . Very cheap one. Every time I stand up in pedals, chain was scraping front derailler.

    So, maybe 1.5 mm is enough maybe not...
    I think we have to observe this critical place and thats all what we can do at this moment...

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