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Thread: Is this ok?

  1. #1
    Spin-stabilized
    Reputation: bailout's Avatar
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    Is this ok?

    I just transferred my SLX cranks to a new frame with a CK BB. Frame's BB shell is 73mm and there is one 2.5mm spacer on the drive side and none on the other side. I roughly measured the chainline ( I don't have a very accurate means of finding the actual center of the frame) and it was about 50mm +/- a couple mm. Frame specs say 50mm. I also checked the range of the front derailleur sans chain and it looks spot on.
    I was wondering if it was ok for the crank's spindle to not fully mate with the outer 2.5 or so millimeters of the crank arm splines. I did not have problems pressing the crank arms together. I also noticed the same gap during a test fit before I installed the BB. I did notice that the CK BB is almost a couple millimeters longer than the stock SLX BB which I did not install due to an unusually tight fit with the crank spindle.

    Thanks in advance!
    Attached Thumbnails Attached Thumbnails Is this ok?-splines.jpg  

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  2. #2
    mtbr member
    Reputation: JonathanGennick's Avatar
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    In theory, the single spacer should be ok. It's to allow for a chain guide, or for one of those bottom-bracket-mounted front derailleurs. Is it possible though, that the CK bottom-bracket is sized so as to not allow for that extra, right-side spacer? I am suspicious that you report a gap matching the spacer width.

    Were it me, I would put on the Shimano bottom-bracket at this point, and see whether the fit is better. I don't really like that gap that you show in the photo.

  3. #3
    Fat-tired Roadie
    Reputation: AndrwSwitch's Avatar
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    Quote Originally Posted by bailout View Post
    I did notice that the CK BB is almost a couple millimeters longer than the stock SLX BB which I did not install due to an unusually tight fit with the crank spindle.
    Weird.

    The way that the Shimano bottom bracket is supposed to work is that for a 68mm shell, you'd add two spacers (so three, total) and for a 73mm shell, you wouldn't. How much wider are the King bottom bracket cups? It sounds like they may have sort-of incorporated some of the width of the two additional spacers in the bottom bracket itself. That makes me nervous - it means you're putting the left crank arm further out on the spindle than spec. I'd be worried about the position of the spindle in the left side cup, too.

    It's always been a little difficult for me to get Shimano cranks into their bottom brackets - as in, rubber mallet difficult.
    "Don't buy upgrades; ride up grades." -Eddy Merckx

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