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stuck seat post - help please

plumpyplumpy Posts: 124
edited January 2011 in Workshop
It's a carbon seatpost in a titanium frame. It's not completely seized, I can (just) rotate it (with an enormous effort), but I can't get any leverage to withdraw it from the frame.

Any tips gratefully received. I'm prepared to countenance methods which irrevocably damage the seatpost, (although I'd rather not, obviously) as I'm taking it out to replace it - but I'm terrified of damaging the frame.

Also, how do I stop it happening again? I used carbon fibre assembly paste on this seat tube when I inserted it, was that wrong?

cheers

Posts

  • Mr PlumMr Plum Posts: 1,097
    May be terribly low-tech and obvious, but have you tried WD40?
    FCN 2 to 8
  • sheffsimonsheffsimon Posts: 1,282
    If you can rotate it, then I would get the end of the seat post in the vice and twist and pull at the same time.

    Something will give eventually.
  • read these

    If you want to dissolve it piranha solution will dissolve the carbon fibre and leave the Ti alone. Personally I wouldn't because it is a) pretty noxious and b) going to explode! Piranha is however generally awesome stuff!!!!!!!

    Try the vice and twist method but make sure you've completely removed the seat clamp.

    Alternatively just chop the seatpost off and then cut down it's length with a hacksaw blade take all the same precautions you would with cutting bars/steerer tubes (ie keep it well moistened (i'd personally fill the whole thing with water and cut underwater) and use a high quality dust mask and nitrile gloves)
  • benpinnickbenpinnick Posts: 4,148
    Have you tried pouring some hot water on the parts? Ti will expand faster than the carbon post when heated, which might give you some wiggle room.
    A Flock of Birds
    + some other bikes.
  • plumpyplumpy Posts: 124
    Thanks for these - I hadn't seen the Sheldon Brown stuff either. I followed his advice - put an old saddle on the post, put a long bar through the saddle rails for leverage, and used brute force (I'd already tried penetrant oil, and warming the seat tube with hot water).

    Turns out that unknown to me the seat tube was shimmed, the seatpost was seized to the shim, and the shim was rotating in the frame. I managed to extract it - both seatpost and shim are now knackered, but the frame seems ok (I hope).

    I guess I now have two choices - shim the tube back down to 27.2, or just go to a 31.6 post - that's supposed to be the less comfy option - what do you think?
  • topdudetopdude Posts: 1,557
    27.2 plus a new shim and remove / clean it all several times a year to prevent it happening again :D
    He is not the messiah, he is a very naughty boy !!
  • puptonpupton Posts: 1
    same problem, carbon post, ally frame, man is it stuck

    put an entire can of wd40 in the frame upside down to soak no luck. I was going to place it in a vice (low down so not to deform the post and the frame) and try heat on the frame and wiggle the frame at the same time.

    Fingers crossed.

    P.
  • nicklousenicklouse Posts: 50,675 Lives Here
    WD40 is a Water Displacer. Plus Gas is a Dismantling Lubricant.

    read the link above to Sheldons pages on stuck seat posts.
    "Do not follow where the path may lead, Go instead where there is no path, and Leave a Trail."
    Parktools :?:SheldonBrown
  • hondicusphondicusp Posts: 168
    I recently used the Effeto Carbomove spray to try and get the carbon seatpost out of an Alu frame. It was absolutely blinkin marvellous. Basically put on old saddle on for leverage, sprayed around the seatpin/frame junction and left to soak in, repeated a couple of time and bingo, I got movement after about 20 mins and seatpin completely removed after 40 mins. I basically left it for 5 mins between each attempt to move it a bit more as I read somewhere that the carbon expands with the friction of extracting it, not sure if this is true. both frame and seatpin are undamaged by the process. Not sure if I was just lucky and my seatpin was not heavily fused into the frame but I hadn't been able to move it for about a year previously...... so based on my experience I cant recommend it highly enough.
  • darren Hdarren H Posts: 122
    Use a hairdryer around the seat tube area, gently , it's worth a try just to expand it. Get someone else to help you give it a good tug
  • Monty DogMonty Dog Posts: 20,614
    Quote: I guess I now have two choices - shim the tube back down to 27.2, or just go to a 31.6 post - that's supposed to be the less comfy option - what do you think?

    Get an acetal (plastic) shim like USE and fit a 27.2mm post. Acetal has the advantage that virtually nothing can stick to it.
    Make mine an Italian, with Campagnolo on the side..
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