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


Retired Brit living in Spain
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.
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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.
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.

Ajax Bay

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.
Yup, spraying stuff on doesn't work. You can try the caustic soda bomb (I'm still wincing and feel little itchy splotches on my face and hands) or all the stuff you can read about on the internet ranging from Coke to organic lime juice, nothing works. Keep this recipe for when you decide to take the plunge:

1) Get a new seatpost now. Look out for an attractive bargain, buy it and store it.
2) Saw the existing post off 25mm above the frame collar.
3) Remove the hacksaw blade from the saw frame and wrap a cloth around one end. Keep beer on hand and swallow some patience. This is not quick.
4) Have a nice small torch handy.
5) Saw vertically through the remainder of the post stuck inside the frame. The idea is to saw a slot right through the post wall along the length of the post. You will score the frame but be patient, look frequently and adjust your aim as needed.
6) Once you are right through (you'll notice a different colour come through as you nick the frame, take a sip of beer.
7) Now take a pair of standard pliers or one of those hinged pliers (not longnose, you will destroy it) and grip the seat post stubby right next to the slot and wind the post up inwards. By that I mean you open it like an old fashioned sardine can.
8) As soon as the tube bends inwards, pressure is immediately relieved and it will come out in one piece. This seems surprising to most people but remember, it is stuck not through adhesion but through swelling. There is no bond between post and frame.
9) Clean as described above and fit your new post using copper compound or similar.
10) Promise yourself you will remove and check it every six months.
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Puzzle game developer
Send it to The Seatpost Man (http://theseatpostman.com/)- he's brilliant
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.


. 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 .
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.
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