What's your formula for freeing off a VERY stuck seatpost?

Discussion in 'Bicycle Mechanics and Repairs' started by rafiki, 24 Aug 2018.

  1. rafiki

    rafiki Über Member

    I'm looking for ideas. It's an aluminium seatpost in a steel frame. I've tried lots of force with the help of friends but no luck. I've been pouring in WD40 and riding rough roads with no seatpost clamp for a couple of weeks, same result. Someone mentioned Coca Cola, does that help? I'm stuck - figuratively and literally! Oh, one potentially complicating factor - it's a Thudbuster LT seatpost! Any advice will be appreciated.
    Last edited: 26 Aug 2018
  2. JhnBssll

    JhnBssll Über Member

    There comes a point where you have to decide whether you're willing to sacrifice the post to save the frame. It sounds like you're getting close to it.

    I've heard of people using a ground anchor and some straps around the BB then using an engine hoist attached to the seatpost to put tension on it, depending on the hoist you can put up to a couple of tons of tension through it that way.

    Another option is cut the post off a few inches above the top of the frame and try and carefully cut a slot down it. Pop a hole through the top to pull it out. It's scary and beyond my skill level but tends to work.
  3. dodgy

    dodgy Guru

    Wd40 isn't much use. Try some Plusgas.
    plantfit and rrarider like this.
  4. JhnBssll

    JhnBssll Über Member

    Yeah plusgas is my go to penetrating agent. Could also whip the bottom bracket out and get in to the bottom of the seat tube for a good spray
  5. Reiver

    Reiver Ribbit, Ribbit.

    give the penetrating oils a good go and give them time to soak in but it will have corroded itself into place - often the only practical solution, and it is a horrible job is to cut it out with a hacksaw blade. get the hacksaw blade in longways, give it half hour a night, you will be through in a week, then knock a chisel down the side and with mole grips and a lot of swearing it will come out.

    glad i'm not having to do it

    best of luck.
    raleighnut and JhnBssll like this.
  6. Cycleops

    Cycleops Guru

    Accra, Ghana
    You could try the cola, up end the bike and pour some in from the BB and leave it for a day or two. A long handled pipe wrench might also help. You need to be careful how much force you use as it could bend the frame irreparably.
    classic33 likes this.
  7. If it’s totally stuck, there’s no solution. You can try using the bike as the lever ( put the saddle in a vice then turning the bike ) but you’ll more than likely crack the frame . If the seat post is wedged it’s time for N+1.
  8. rogerzilla

    rogerzilla Guru

    Heat the seat tube quickly with a hot air gun then try to twist the post.
  9. Cycleops

    Cycleops Guru

    Accra, Ghana
    With a handle like @rogerzilla the OP might like to employ your expertise :smile:.
    JhnBssll likes this.
  10. Ajax Bay

    Ajax Bay Veteran

    East Devon
    Recommend the OP reads this 2015 thread:
    Page 3 - YS (no longer otp) recipe (which was addressing Al seatpost in a steel frame but would work (just will take longer with a steel seatpost). And I'm not sure in steel/steel the observation (in (8) below): "it is stuck not through adhesion but through swelling. There is no bond between post and frame." still holds. I can see oxides having a 'sticking' effect.
    Last edited: 30 Aug 2018
    JhnBssll likes this.
  11. iluvmybike

    iluvmybike Well-Known Member

    slowmotion likes this.
  12. ColinJ

    ColinJ It's a puzzle ...

    Ok then - how would Seatpost Man do it? :laugh: (No doubt it is a trade secret!)

    I would like to free my nice Ti seatpost from its Al framed captor, but only if it could be done without damaging either, which I suspect is not possible. Fortunately, my saddle height is acceptable as it is. I'd like to experiment with minor changes, but can get by without.
  13. SkipdiverJohn

    SkipdiverJohn Über Member

    As a last resort, I would weld a 6" long bit of bar or box section steel to the top of the seat post and clamp it in a big bench vice using that - then twist the bike frame CAREFULLY in both directions, possibly with a piece of threaded rod clamped across the rear dropouts (like you would do if resetting the internal width) so you don't bend either stay in or out.
    Before going to that extreme I would try multiple heating and penetrant spraying cycles, using a blow torch and diesel, ATF, or a mixture of both, in one of those little gardeners trigger bottles.
  14. MontyVeda

    MontyVeda a short-tempered ill-controlled small-minded troll

    How about something like this...
    ...obviously replacing the Levi's with your bike.
  15. wheresthetorch

    wheresthetorch Dreaming of Celeste

    West Sussex
    This is how I did it - or rather how a mate did it for me. Here's a pic of it once it was out.
    SkipdiverJohn likes this.
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