Crack at the top of carbon fibre seat tube.

zhang
zhang Posts: 222
edited June 2014 in Workshop
My frame has a crack in the seat tube just below the seat tube clamping area. Has anyone here had this type of damage repaired before? I've seen a lot of documented cases from both professional repairers and DIYers of cracks/holes further down the tubes which have been repaired by wrapping new carbon around the whole circumference of the tube but not seen any before/after pictures of this type of crack, where I don't think you can get new carbon sheets all the way around the tube.

2014-06-07%2016.33.14.jpg

Comments

  • slowbike
    slowbike Posts: 8,498
    That looks like something that could be repaired - with the repair it'll probably end up stronger than the original!
  • rolf_f
    rolf_f Posts: 16,015
    Would it even be sufficient to just drill a hole in the end of the crack to stop it propagating? If the seatpost is long enough surely it would still be able to do its job even with the crack present.

    Better perhaps also to have the clamp bolt away from the slot?
    Faster than a tent.......
  • Matthewfalle
    Matthewfalle Posts: 17,380
    Didn't I read somewhere that it is best practice to have the clamp slot on the other side to he frame slot (ie s/clamp slot facing forward)?
    Postby team47b » Sun Jun 28, 2015 11:53 am

    De Sisti wrote:
    This is one of the silliest threads I've come across. :lol:

    Recognition at last Matthew, well done!, a justified honour :D
    smithy21 wrote:

    He's right you know.
  • zhang
    zhang Posts: 222
    I don't think drilling a hole works the same in CF as it does with metals. And yes, I normally run the clamp with the slot facing forwards. I had the seatpost and clamp off before taking the photo so the photo doesn't show it in it's normal position.
  • tuneskyline
    tuneskyline Posts: 370
    http://www.fibre-lyte.co.uk/fl/bicycle/ ... e2011.html

    or you could just very carefully take your time just sandpaper the area of the crack away. You could do a nice job and make it look as though it's a larger u shape if you get me. That's what I would do.
  • jermas
    jermas Posts: 484
    If you can't get it repaired, you could permanently bond (epoxy) the seatpost into the frame. Just make sure it's the correct height and straight.
    If it's a non aero seatpost you could use a double seatpost clamp http://www.rosebikes.co.uk/article/xtreme-wcr-double-clamp-seat-tube-clamp/aid:255007 which would hold the post without straining the frame.

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