Seized seatpost - BAD

jamlala
jamlala Posts: 284
edited April 2018 in Workshop
Hi all

My metal (I think) seatpost has seized into my carbon bike frame and WILL NOT BUDGE!
I have tried:-
a) constant boiling water drenchings,
b) weeks of WD40 spraying hoping that it will gradually sink in
c) brute force
d) brute force
e) brute force!!

I have take it to my LBS and they can't fix it. Please does anyone have any clues?!!
Cannondale Supersix 105 2013- summer bike - love it!
Cannondale CAAD12 - racing fun!
Trek Crockett 5 - CX bike, muddy fun!
Scott Scale 940 MTB XC racer.
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Comments

  • cooldad
    cooldad Posts: 32,599
    Clamp the seatpost in a large vise.

    Use the frame as a giant lever.
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  • jermas
    jermas Posts: 484
    You could try a shock / freeze release spray. The spray rapidly cools the metal causing it to shrink and (hopefully) breaks through the corrosion.
  • kingdav
    kingdav Posts: 417
    I've not used him but heard mention before of theseatpostman
  • Had this on a planet x frame. In the end I cut the seat post down an inch from the collar then carefully sawed the seat post from inside in 2 places. This took around at hour for each cut then carefully peeled them inwards. 3 hours later seat post out snd no damage.
  • sungod
    sungod Posts: 16,497
    aluminium alloy/cf, probably galvanic corrosion, the corrosion product has greater volume that the original metal of the post, it jams solid

    wd40 won't help, it'll just make it much harder to get anything in there that might dissolve the corrosion product, boiling water will expand the alloy, making it tighter

    as above, try freezer spray inside the post, it might create enough differential contraction to loosen it, try twisting the post before it warms, otherwise careful but laborious cutting is what i'd try next

    next time use anti-seize
    my bike - faster than god's and twice as shiny
  • svetty
    svetty Posts: 1,904
    Fingerling wrote:
    Had this on a planet x frame. In the end I cut the seat post down an inch from the collar then carefully sawed the seat post from inside in 2 places. This took around at hour for each cut then carefully peeled them inwards. 3 hours later seat post out snd no damage.

    This. You just have to hope that the corrosion doesn't extend too far down the post. Careful use of a sharp hacksaw blade and you should be OK
    FFS! Harden up and grow a pair :D
  • Can of coke into the seat tube while bike is upside down, leave for a day, put bike right way up and use rubber mallet to knock post into tube to free it.

    Certainly works for alloy frames and posts, did it myself ~20 years ago, not tried with carbon frame.
    ================
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  • Monty Dog
    Monty Dog Posts: 20,614
    Coke contains a mild phosphoric acid which is great for removing rust. The galvanic corrosion which creates aluminium oxide and is jammng your seatpost requires a strong alkali to dissolve it. By all means empty a can of Coke down your seattube but you'll probably only make it stickier. Try something like ACF-50 instead.
    Make mine an Italian, with Campagnolo on the side..
  • Another for the Seatpostman - east, quick, cheap and no damage
  • shaw8670
    shaw8670 Posts: 264
    I found sawing impossible. I cut it off 2cm above the collar and used a big rough round file and filed it thin. I had more control and could do it evenly. I filed in 3 places until they got thin , then started folding it inwards with pliers and more filing and tapping to break loose.
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  • davidof
    davidof Posts: 3,035
    I used a corrosion dissolving product which I left in for days then a long lever. That was after trying everything else (vice etc). The seatpost was really really stuck. See video:-

    https://youtu.be/Bfb6Ejb7pS4

    It is hard to get the leverage on a post.
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