Seized seatpost

MidlandsGrimpeur2
MidlandsGrimpeur2 Posts: 2,115
in Workshop
So my Thompson seatpost has completely seized in my caad12 frame (aluminium on aluminium). Not sure how as I check it regularly and adjusted the height not that long ago.

I know there are lots of supposed ways of freeing it but not sure which actually work.

Any tips?

Brute force and a vice isn't shifting anything so far.

Comments

  • shirley_basso
    shirley_basso Posts: 6,195
    Coca cola
    Plusgas (whatever that is)
  • MidlandsGrimpeur2
    MidlandsGrimpeur2 Posts: 2,115
    Cheers!

    Looks like it is a quick release aerosol. There is a Screwfix nearby and they have stock. Will pick up a can tomorrow and see how it does.
  • shirley_basso
    shirley_basso Posts: 6,195
    If it's a disaster there's a guy online called the seatpost guy who will cut it out and save the frame but lose the seatpost
  • N0bodyOfTheGoat
    N0bodyOfTheGoat Posts: 6,057
    Back in 90s I turned my Peugeot 531 upside down, can of coke into holes by BB, next day turned bike right way up and gently hit saddle top covered by wood with mallet... Free within a few hits.
    ================
    2020 Voodoo Marasa
    2017 Cube Attain GTC Pro Disc 2016
    2016 Voodoo Wazoo
  • trevor.hall12
    trevor.hall12 Posts: 483
    If all else fails cut it off flush and get a big enough drill ,1/2 mm smaller than the seatpost and drill it .For alloy ones the bit will find it's centre .
    Or take it to a steelwork shop with a bench drill .
    Done carbon and alloy this way .It is extreme and only a last resort after all the above fails
  • arlowood
    arlowood Posts: 2,561
    Slightly more expensive option is to saw it off flush with the top of the seat tube and use an expanding reamer to ream out the vestiges of the old post. Something like this might do the job if it's a standard 27.2mm seat post.

    https://www.rdgtools.co.uk/acatalog/HSS-ADJUSTABLE-METRIC-REAMER-27MM---30MM-9420.html
  • MidlandsGrimpeur2
    MidlandsGrimpeur2 Posts: 2,115
    Cheers all. I did read about the cutting option. Definitely a last resort as you all say. Off to pick up the plusgas in a bit, hopefully that will do the trick!
  • me-109
    me-109 Posts: 1,915
    Heat gun on the seat tube. That will expand more than the seat post.
  • MidlandsGrimpeur2
    MidlandsGrimpeur2 Posts: 2,115
    No joy with the plusgas. Will try the heat option next. Read the hot water option is a bit more friendly than heat gun, there is a gcn vid which shows you need to douse it several times over the course of an hour or two to give it the best chance.
  • andyrr
    andyrr Posts: 1,823
    Worth dismantling the seatpost and giving the bare post a few taps (using a block of wood or similar to protect the end. Your potentially pushing it into the frame but it might start it moving?
  • masjer
    masjer Posts: 2,655
    MidlandsGrimpeur2 said:

    No joy with the plusgas. Will try the heat option next. Read the hot water option is a bit more friendly than heat gun, there is a gcn vid which shows you need to douse it several times over the course of an hour or two to give it the best chance.

    It might be an idea to turn the bike upside-down, remove a bottle cage bolt and spray the plusgas around the walls of the seat tube. Do it a few times and leave it to soak in.
    A slide hammer would be good too.

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