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  1. #1
    mtbr member
    Join Date
    Oct 2011

    overclamped carbon seatpost

    I rolled the dice on a FSA carbon seatpost off ebay. I may have crapped out.

    The seatpost shows signs of over-clamping. It looks like the post was overclamped, then the person slide the seatpost to a different position and then overclamped again. The result is two shallow indentations (maybe 1 mm deep) along the back of the post. However, even with a small magnifying glass, I couldn't see any cracks. My hope is that the indentations are just the clear coat.

    Being at the back of the seatpost, the indented areas would be under compression. So maybe less likely to form a crack? However, it is a setback seatpost, so it would possibly create a stress concentration that would lead to buckling?

    Anyone with some carbon knowledge have thoughts on this?
    Attached Thumbnails Attached Thumbnails overclamped carbon seatpost-clamp_mark.jpg  

  2. #2
    mtbr member
    Join Date
    May 2010
    Can you rotate 90 degrees so we can see if there's truly an indentation, or if it's just in the clearcoat?

  3. #3
    PMK is offline
    mtbr member
    Reputation: PMK's Avatar
    Join Date
    Oct 2004
    Where do you plan to clamp it, above or below the indentations?

    FWIW, fiber construction works well in tension not compression. Compare it to tying your shoes. Pretty easy always pulling to get them tight and tied, trying to push the shoelace would not work well.

    Reps! We don't need no stickin' reps!

  4. #4
    Helmetless Crasher
    Reputation: Stumpjumpy's Avatar
    Join Date
    Sep 2011
    My FSA setback carbon post began to fail shortly after being over-clamped like that by a kid at the LBS (the kid trq'ed it so hard the clamp was stretched/distorted). Listen for a cracking sounds to ensue.
    '95 M2 StumpJumper FS
    '11 Cannondale RZ 120-two

  5. #5
    mtbr member
    Reputation: loggerhead's Avatar
    Join Date
    Mar 2009
    same thing happened with my ec90 post. Now it has smaller spider crack. Sucks but I'm waiting for a catastrophic failure to get a dropper post.

  6. #6
    mtbr member
    Join Date
    Jun 2008
    I would not use that post...a catastrophic failure may be in your future. Seems like the rider has very little post exposed. With little post exposed, the flex part of carbon is neutralized. Why not just take a strong aluminum post and cut it to desired length? Remember that you want the end of the post and inch or more below the top tube intersection.

  7. #7
    mtbr member
    Join Date
    Dec 2012
    Discard the seatpost asap.

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