Right side crank hits/scrapes my chainstay under power pedal stroke- Mtbr.com
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  1. #1
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    Right side crank hits/scrapes my chainstay under power pedal stroke

    I know I'm not the strongest dude out there but my crank scrapes on the right side against my chainstay when I'm really digging into my pedal stroke, especially when climbing. I have a nice scraped part of my frame on the chainstay now. It's an annoying/embarrassing sound too. It happened using some old XTR 962's and now it's happening (as of last week) on my SLX crankset less than a year old. Did I wear out my BB cups? I can press the crank against the chainstay with my hands with not too much force. I was going to loosen and tighten the BB cups and the cranks to see if that corrects the issue. Is there an issue with my right leg not pedaling straight (lol)? Do I need a stiffer crank arm or is that not a factor? ...or tougher BB cups? Would NEW BB cups help? Any suggestions or ideas? Thanks!

  2. #2
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    Have you checked your frame alignment? There should be a reasonable amount of clearance ~10mm ish I would say both left and right. You certainly shouldn't be able to flex a crank by enough to do that unless you are complete beast or on some very powerful performance enhancers
    Did you install the spacers correctly on the BB when you installed it? (2 drive side 1 non drive side for 68mm BB, 1 drive side for 73mm)

  3. #3
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    Yep, there should be almost NO lateral movement in cranks. There's either something majorly wrong with the fitting, the cups (which would feel like pedalling a novelty bike and sound horrendous due to creak), or the frame is cracked.

    I've got a tight BB and a pretty stiff crank like an SLX.......I can get about 3-5mm movement with extreme force.
    Rimmer - "There's an old human saying - if you talk garbage, expect pain"

  4. #4
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    Right side crank hits/scrapes my chainstay under power pedal stroke

    Quote Originally Posted by dbbarney View Post
    I know I'm not the strongest dude out there but my crank scrapes on the right side against my chainstay when I'm really digging into my pedal stroke, especially when climbing. I have a nice scraped part of my frame on the chainstay now. It's an annoying/embarrassing sound too. It happened using some old XTR 962's and now it's happening (as of last week) on my SLX crankset less than a year old. Did I wear out my BB cups? I can press the crank against the chainstay with my hands with not too much force. I was going to loosen and tighten the BB cups and the cranks to see if that corrects the issue. Is there an issue with my right leg not pedaling straight (lol)? Do I need a stiffer crank arm or is that not a factor? ...or tougher BB cups? Would NEW BB cups help? Any suggestions or ideas? Thanks!
    If you can press the crank arm against the chainstay and you hadn't had any issues for a year, something definitely loosened or has a crack. Could be the BB was not installed with sufficient torque. I recommend you have someone assist with determining the cause instead of loosening and tightening the BB cups.
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  5. #5
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    Is the non drive arm equally as close? Might be something simple like having your spacers in the wrong spot.

  6. #6
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    I figured it out. My VPP is shot. Thanks tho.

  7. #7
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    Yep, that'll do it.
    Rimmer - "There's an old human saying - if you talk garbage, expect pain"

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