what is acceptable min clerance between chainstay and inner crankarm?- Mtbr.com
Results 1 to 12 of 12
  1. #1
    Hack Racer
    Reputation: Cheers!'s Avatar
    Join Date
    Jun 2006
    Posts
    2,559

    what is acceptable min clerance between chainstay and inner crankarm?

    Guys,

    Question. What is the min acceptable clearance between the chainstay to inner crankarm?

    XTR FC-M985 has measurement from centre of BB to inside of pedal arm to be 66.0mm.

    My lynskey M230 frame has a width at that location of 125mm. If I divide by 2, that is 62.5mm

    That would give me only 3.5mm... Is that way too close? Will the Ti frame flex enough under cornering that while I pedal the crank arm will make contact with the pedal arm?

    Thoughts?

  2. #2
    mtbr member
    Reputation: elcaro1101's Avatar
    Join Date
    Sep 2011
    Posts
    509
    I think the BB shell width is what you need to measure, then use this document to decide what spacers you need to use based on the width and FD type.

    http://techdocs.shimano.com/media/te...9830726445.PDF

    All installed correctly, I think its safe to assume Lynsky made sure it will work. If your too heavy though, then all bets are off. I have no problems with my ti frame and Im not a small guy, but it isnt a Lynsky .

  3. #3
    Nouveau Retrogrouch SuperModerator
    Reputation: shiggy's Avatar
    Join Date
    Dec 1998
    Posts
    48,236
    Quote Originally Posted by Cheers! View Post
    Guys,

    Question. What is the min acceptable clearance between the chainstay to inner crankarm?

    XTR FC-M985 has measurement from centre of BB to inside of pedal arm to be 66.0mm.

    My lynskey M230 frame has a width at that location of 125mm. If I divide by 2, that is 62.5mm

    That would give me only 3.5mm... Is that way too close? Will the Ti frame flex enough under cornering that while I pedal the crank arm will make contact with the pedal arm?

    Thoughts?
    0.001mm

    If the ring does not rub in use, it is fine.
    mtbtires.com
    The trouble with common sense is it is no longer common

  4. #4
    Hack Racer
    Reputation: Cheers!'s Avatar
    Join Date
    Jun 2006
    Posts
    2,559
    So there is no chance the frame will flex enough under cornering loads to cause the chanstay to make contact with the crankarm?

    Seeing how the Shiggy has spoken I will take your word on it.

  5. #5
    LightJunction.com
    Reputation: lightjunction's Avatar
    Join Date
    May 2011
    Posts
    774
    I'm not aware of one. There should be enough clearance that when you're pedaling, even under stress, the arm doesn't hit the chainstay. Other than that, you should be fine.
    We sell quality bike headlights and flashlights.
    www.LightJunction.com

  6. #6
    mtbr member
    Reputation:
    Join Date
    Feb 2010
    Posts
    176
    I would like to follow up on this a little. I am installing a Midleburn duo(isis) on my bmc fs 01. When I had this installed on my Superlight I was using a 108mm bb to get a good chainline to run big/big. With the elevated chainstays had no clearance issues with crankarms. On the bmc clearance is minimal, like 1-2mm. No issue with chainrings. I am very leary of the arms being that close to the carbon stays as I am cranking those babies around. Should I be worried or give it a try.

  7. #7
    mtbr member
    Reputation: G-Choro's Avatar
    Join Date
    Jul 2010
    Posts
    622
    i just installed the XTR 985 race cranks as well. rings have no problem, but my drive side crank clears the chainstay by 1.5 to 2mm at most. the NON-drive side has at least twice that clearance. what is more of a concern to me than clearance is the fact that the cranks don't appear to be centered in relation to the center line of the frame.

  8. #8
    Nouveau Retrogrouch SuperModerator
    Reputation: shiggy's Avatar
    Join Date
    Dec 1998
    Posts
    48,236
    Quote Originally Posted by Cheers! View Post
    So there is no chance the frame will flex enough under cornering loads to cause the chanstay to make contact with the crankarm?

    Seeing how the Shiggy has spoken I will take your word on it.
    Please note I said "in use." Amount of flex in a bike varies.

    IME 3.5mm is HUGE clearance.
    mtbtires.com
    The trouble with common sense is it is no longer common

  9. #9
    Hack Racer
    Reputation: Cheers!'s Avatar
    Join Date
    Jun 2006
    Posts
    2,559
    How much clearance should be the minimum for between the big chain and the chainstay?

  10. #10
    Nouveau Retrogrouch SuperModerator
    Reputation: shiggy's Avatar
    Join Date
    Dec 1998
    Posts
    48,236
    Quote Originally Posted by Cheers! View Post
    How much clearance should be the minimum for between the big chain and the chainstay?
    If it does not rub in use, a miss is good as a mile.
    mtbtires.com
    The trouble with common sense is it is no longer common

  11. #11
    Hack Racer
    Reputation: Cheers!'s Avatar
    Join Date
    Jun 2006
    Posts
    2,559
    I realize this too. But buying an expensive crankset and it not working becomes an expensive experiment.

  12. #12
    Hack Racer
    Reputation: Cheers!'s Avatar
    Join Date
    Jun 2006
    Posts
    2,559
    I realize this too. But buying an expensive crankset and it not working becomes an expensive experiment.


Members who have read this thread: 1

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •  

THE SITE

ABOUT MTBR

VISIT US AT

© Copyright 2020 VerticalScope Inc. All rights reserved.