Seized seatpost

camsdad
camsdad Posts: 3
edited October 2014 in Workshop
My Trek 1.9 has a carbon seat post in an aluminium frame. I've recently discovered that the seat post is jammed solid, I'd really like to be able to move it so I'm open to suggestions.
Previous posts have suggested heat to free up the post, however I don't relish ruining the paintwork.
I plan to borrow a large stillson pipe wrench to attempt to rotate it free again, however I'm worried that the tube will just collapse under the pressure. I don't mind ruining the tube but I'm really worried about trashing the frame.
Any suggestions?

Comments

  • keezx
    keezx Posts: 1,322
    Clamp the post head in a vise and turn.
    If it comes loose > okay, if it breaks cut out the pieces with a sharp screwdriver or something.

    What is the lesson you have already learned?
  • camsdad
    camsdad Posts: 3
    I've learned not to leave things tIll they seize up :(
  • dj58
    dj58 Posts: 2,223
    This subject was discussed a few months ago as I recall. One of the suggestions was to remove the BB and spray this into the seat tube and leave to act. http://www.sigmasport.co.uk/item/Effett ... -200ml/286
  • nicklouse
    nicklouse Posts: 50,675
    camsdad wrote:
    My Trek 1.9 has a carbon seat post in an aluminium frame. I've recently discovered that the seat post is jammed solid, I'd really like to be able to move it so I'm open to suggestions.
    Previous posts have suggested heat to free up the post, however I don't relish ruining the paintwork.
    I plan to borrow a large stillson pipe wrench to attempt to rotate it free again, however I'm worried that the tube will just collapse under the pressure. I don't mind ruining the tube but I'm really worried about trashing the frame.
    Any suggestions?
    Before doing anything read this http://sheldonbrown.com/stuck-seatposts.html
    "Do not follow where the path may lead, Go instead where there is no path, and Leave a Trail."
    Parktools :?:SheldonBrown
  • crikey
    crikey Posts: 362
    Stop fannying about and get a big hacksaw blade and cut it out.

    The problem is electrolytic corrosion between the post and the frame which is remarkably resistant to any spray or fluid.

    You can tell when you've cut far enough by the change in sound; carbon sounds different to alloy.

    If you think I'm being a bit cavalier, try cutting an alloy post out of a carbon frame like I did...
  • frisbee
    frisbee Posts: 691
    Hair dryer heat shouldn't damage the paint but keep it moving to avoid hot spots.
  • cycleclinic
    cycleclinic Posts: 6,865
    Next time smear everything in carbon paste and renew it regularly.
    http://www.thecycleclinic.co.uk -wheel building and other stuff.
  • lpretro1
    lpretro1 Posts: 237
    Try this guy - he is very good - www.theseatpostman.com
    Not cheap but its a lot cheaper than a new frame!
  • term1te
    term1te Posts: 1,462
    crikey wrote:
    Stop fannying about and get a big hacksaw blade and cut it out.

    The problem is electrolytic corrosion between the post and the frame which is remarkably resistant to any spray or fluid.

    You can tell when you've cut far enough by the change in sound; carbon sounds different to alloy.

    If you think I'm being a bit cavalier, try cutting an alloy post out of a carbon frame like I did...

    I always thought that electrolytic corrosion occured when two dissimilar metals were in contact in a solution of ions? If the seatpost is carbon, is it just corrosion of the aluminium frame? I believe the oxides of aluminium take up more space than aluminium, so it squeezes the seatpost in place. I've heard of people have success filling the seat tube with coke from the BB end, the acid in which dissolves the corroded material. It worked for me when I was trying to get an old corroded quill stem out of the steer tube of some forks. Although the large mallet also helped.
    The Master
    The Moser
    The VN
  • lapavoni10
    lapavoni10 Posts: 146
    I am with Crikey on this one...., saw the top off the post (remember to leave plenty of post to get hold of), wrap a long hacksaw blade in tape at the end to hold it, make sure you have the blade parallel to the post and away you go. When you are through one side, you may even be able to squash the post with a vice and shift it....
  • craker
    craker Posts: 1,739
    I used my carbon seatpost for a few months on my MTB (lots of up and down) then put it back in the road bike where I subsequently found it stuck fast.

    I did try heat (lots, not bothered about the paintwork too much) but carbon splinters as soon as you get pliers or a vice on it.

    I ended up drilling it out with a 26mm wood drill bit.

    http://www.amazon.co.uk/Flat-wood-drill-bit-26mm/dp/B0070Z80NC

    You'll only be able to go as deep as the bit length, I got 20 cm or so down and bashed the rest deeper into the frame to give me enough space for a new post.

    It gets most of the material out and what's left is so weak you can pick at it with pliers, screwdriver blades whatever.

    Carbon dust is pretty evil stuff from what I understand, I did mine outside with a face mask on and let the breeze carry the debris away.
  • CiB
    CiB Posts: 6,098
    You need leverage. Remove the seat, take the bike to the nearest roadside drain and turn it upside down. You might be lucky and find that the seat clamp slots into the drain cover - mine did. If it does, fit it into the drain cover and twist the frame. One of three things will happen - the seatpost will free itself and start to turn in the frame so you can get it out; the drain cover will pop out; or the seat clamp will break free from the post. #3 happened to me, but it was worth a try. Ended up at the LBS where his massive vice + huge plumbers pipe grips eventually got it out, but it was a big job.
  • keezx
    keezx Posts: 1,322
    A vise is the mot useful tool for these jobs, it's just brute force that does it.

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