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    I bought a BMX with a bastardized seat post crammed into the frame. I’ve tried a pipe wrench and penetrating oil. How can I get this thing out?

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    17 Comments

    1. MGTS on

      Penetrating oil overnight. Clamp the post in a bench vise. Heat on the seat tube. Use the frame as leverage. Twist and pull

    2. oldfrancis on

      I would recommend running this through multiple cycles of heat and penetrating oil.

      Heat the seat tube. You can use a blow dryer on high or a heat gun on low (be careful with the heat gun that you don’t end up blistering the paint).

      Apply heat, then spray the penetrating oil. Wd-40 will do.

      Let the penetrating oil get drawn between the seat tube and the seat post.

      Heat it again.

      Add penetrating oil.

      Wait.

      Heat, oil, wait.

      Since the seat tube itself is pretty much destroyed I would use a pipe wrench to try and get it to rotate.

      I have been pretty lucky that this technique has worked for me and I have never failed to remove a seat post.

    3. Tcih on

      Clamp it by seatpost and use whole bike frame to wiggle it out. If that does not work then saw it into pieces from inside out.

    4. network-ned on

      Aluminium post in a steel frame? Caustic soda. Cut post off short. Stretch inner tube over the end and tie a knot in it close to the post. Remove cranks and bottom bracket. Turn frame upside down and pour caustic into the seat tube. Be careful – it will get VERY HOT. Once it’s cooled, pour out the liquid and repeat. After 8 or 10 repetitions you should have dissolved the seat post.
      This works, I’ve done it myself two or three times now.

    5. Blitzed_ca on

      Get a blade from a hacksaw and hold it with a pair of vise grips, then slowly and steadily cut through the seat post from the inside (lengthwise)

      Eventually you’ll be able to crush it in on itself and you can pull it out

      Just be careful to not angle the blade, so you get a straight flat cut through the pipe

      If the post remains are too long, you’ll have to cut off part of it to shorten the pipe first

    7. littlecogBigcog on

      In addition to the other comments, you could also try giving it a whack with a hammer straight on top. Wrap something around it so it doesn’t slide down in the event this works

    8. FastSloth6 on

      That drilled hole suggests someone tried some aggressive measures already. You could fit a rated steel bolt through and try to either twist or pull using it for leverage.

      Cycles of penetrating oil and heat, mentioned elsewhere, is fantastic prep.

      I’ve used [this](https://youtu.be/51tcpMS-j1E?si=4K90NXtyTVii5RRj) method before, it got the post out but bent the jack and scratched the paint.

      [What would RJ do?](https://youtu.be/S3ek2GeZzE0?si=RbdvRGsX90U9-j7K)

    10. kingtrollbrajfs on

      I doubt that it’s ever coming out.

      That’s a lot of surface area that has bonded and solidified. Maybe some serious heat, but it would destroy the paint.

    11. Not3kidsinasuit on

      All else fails cut it down until around 1cm is still visible then use a file to cut a groove down the length of the post from the inside. Tap downwards and inwards with a hammer to loosen it and once it budges it should pull out.

    13. jakecbrk on

      Freeze the post. Upside down aerosol can spray will make it cold and pull up.

      The thermal coefficient of expansion is higher for aluminium, so heating the steel frame won’t help. You need to cool the aluminium, so it shrinks away from the steel tube.

    14. davey-jones0291 on

      Heat the outside of the seattube, freeze spray the inside of the seatpost and beat the post like it owes you money. Twist with a mole grip every so often. The nuclear option i used once with an ally post in a steel frame was getting a blacksmith drill bit the same size as the post and drilling very carefully. Got it out and didnt ruin the seat tube of the frame. Luck may have played a part. Good luck

    15. konwiddak on

      Worse case you can buy an adjustable reamer and ream it out by hand, but that’s a slow job – you can probably remove 0.1mm per pass. The tool isn’t that expensive for a cheapo one – but we’re probably talking $30 or so which may not be worth it for *this* frame.

    16. konwiddak on

      Once you get it out, you might need to gently sand the inside of the seat tube – there’s going to be all sorts of corrosion products that will just jam up again if you don’t give the tube a bit of a resurface.

    17. bfarm4590 on

      This works with cars so i reckon it will work here too. Lots of heat on the post then clamp it well and twist it till it starts moving. Lots of oil and slowly slide it out

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