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I have an old steel frame (Columbus Number 2 I think) that has the seat post (Suntour Superbe Pro - see, I said it was old!) rusted in. I have tried lots of WD-40 but it will not budge.
Any tips on how I can get it out without having to cut the frame up?

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Before you take any more forceful measures, it may be a good idea to think a little about chemistry:

  • 'Rust' is typically the name put on any type of corrosion, but technically & specifically, it is the corrosion of iron (or steel) to form iron-oxides.
  • Although your bicycle is most definitely steel, your seatpost is not -- it's aluminum-alloy, which does not 'rust', but definitely corrodes (creating aluminum oxide).
  • WD-40 is a penetrating oil which is designed to, amongst other things, break up iron-oxides. However, it is pretty much useless against aluminum-oxides, especially when they have already corroded & bonded.
  • Ammonia, however, is spectacularly good at eliminating aluminum-oxides.

Therefore, if WD-40 isn't doing the trick, get some ammonia, apply it in a similar fashion, and let it sit. It may just be all you need!

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    This is a very cool tip. You might want to clarify alloy = "aluminum alloy" in this case. If it's an iron alloy (e.g. chromoly) then ammonia won't work.
    – darkcanuck
    Aug 30, 2010 at 17:49
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    Is it dangerous that this will destroy the bike? Are there any risks involved with this?
    – sixtyfootersdude
    Jan 14, 2011 at 23:41
  • Oxalic acid (sold as "wood bleach" at paint stores) will "reduce" rust (iron oxide).
    – Daniel R Hicks
    Jan 13, 2012 at 12:22
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    How do you know that the seatpost is aluminium alloy? Are all seatposts of aluminium alloy?
    – Mads Skjern
    Aug 8, 2014 at 21:28
  • @MadsSkjern Try to stick a magnet to it!
    – Dustin Ingram
    Nov 18, 2014 at 20:36
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This is a tough one. It's not impossible but you really need mechanical advantage. If you can clamp the seatpost, you will get the best chance at freeing this. You will probably damage/lose the seatpost with this method.

  1. Make sure the seatpost is free of grease and oil on the outside.
  2. Turn the frame upside down and clamp the seatpost into a bench vise.
  3. Spray WD-40 into the seattube from the bottom bracket opening.
  4. It will probably be dripping rusty colored oil out the top of the seat tube (which is now facing the floor - you might want to put something to catch the oil under there.).
  5. Carefully hold the head tube and the rear stays and try to rotate the frame on the post.
  6. Work it slowly and carefully being sure not to bend the stays!*
  7. Make sure the seat post is not rotating in the vise (if so, clamp tighter)

This process can take some time. You will need patience and lots of WD-40. Eventually, the post will rotate in the seat tube and you will be able to work it out.

*The trick is knowing how much force to apply. Sometimes you need more than you think and sometimes you apply more than you need (which results in unwanted damage). This difference comes with experience.

Oh and also: grease the new seatpost well before you put it back in - you'll appreciate it later.

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  • "be careful not to bend the stays" You're right, so I think it is better to do that with a rear hub or even wheel tightly attached in place. And have you considered 44-16? I love it! ;o)
    – heltonbiker
    Oct 6, 2011 at 18:07
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    Alternatively you could bore a hole trough the upper part of the seatpost, poke a large screwdriver or another bar and apply torque to the seatpost in order to make it spin. This has done the trick for me when I had the bike assembled or didn't had a vise. You may need somebody to help you to hold the bike or frame.
    – Jahaziel
    Jan 13, 2012 at 20:22
  • Why is it better turning the frame upside down and applying it from that side? Isn't it just as fine to apply it from the outside? Obviously doing both is the optimal, but you just suggest doing it from the difficult angle, and not from the easy angle, and I can't see why :)
    – Mads Skjern
    Aug 8, 2014 at 21:33
  • @MadsSkjern at the very least this allows it to work its way in from both ends, but also you can flood the problem area without too much getting elsewhere in the frame.
    – Chris H
    Aug 11, 2014 at 8:54
  • @Chris: Flooding the inside only lets it work from one end. Obviously it is possible to attack from both ends, but flooding the inside only works from one end. Don't you agree?
    – Mads Skjern
    Aug 12, 2014 at 6:50
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You should check out the 15 Way To Unstick a Seatpost by Sheldon "Unggggghhh!" Brown

http://www.sheldonbrown.com/stuck-seatposts.html

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  • I tried them all. Still fighting. But don't give up, folks! (major problem: ammonia does not penetrate already oiled parts...)
    – heltonbiker
    Oct 6, 2011 at 18:12
  • I recently got a stuck aluminium seatpost out of a steel frame using the sodium hydroxide method. Took quite a while, but it did eventually dissolve it. I spent some time with drills and hacksaw blades first - it was a long thick seatpost.
    – armb
    Mar 20, 2013 at 12:11
  • +1. This month, I freed a stuck seatpost. Sheldon's "use the saddle" and "remove the bolt" suggestions weren't enough. But his "vise" suggestion worked for me, and it didn't even destroy the seatpost. I am grateful for all the work that Sheldon and the new website maintainers have put in.
    – unforgettableidSupportsMonica
    Nov 21, 2013 at 6:06
  • FYI we normally discourage link-only answers because the remote website might reorganise or vanish completely.
    – Criggie ♦
    Aug 19, 2018 at 8:54
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Untested and at-your-own-risk, but this is what I would try:

  1. Soak the rusted join with WD-40 from above and below (ie. flip the frame and spray down the seat tube). Let it sit for a few hours or overnight.
  2. Secure the frame against something solid, like a heavy workbench (not a repair stand!).
  3. Put an old saddle you don't care much about on the seat post.
  4. Hit the side of the saddle's nose with a hammer or mallet. Use short, hard taps -- using wild swings you're liable to hurt yourself or the frame.

The idea is to use the torque of the saddle to break the bond between the post and the frame. You don't need to move the post much. If the post moves, then you should be able to work it loose without the hammer. If it doesn't, then worst case you've destroyed an old saddle.

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Cut the top off of the tube then carefully use a hacksaw blade inside the seat post to cut toward the seat tube. A handle for a hacksaw blade works or just wrap the plain blade with a bit of tape to make a handle. You should then be able to free the old seat post.

Or does the seat post extend way down into the frame? Even then this should help as the WD-40 will get a better chance to reach the lower parts.

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  • Ouch! I was hoping to be able to save the seat post as well if possible. I might have to sacrifice it in the end.
    – Anthony K
    Aug 30, 2010 at 14:38
  • Your seatpost is already most probably gone. Give up on it and save the frame at least! (but of course, you might end up saving the post...)
    – heltonbiker
    Oct 6, 2011 at 18:09
  • If the seat posts reaches far into the frame then I imagine that it is quite difficult to saw it with a hacksaw blade. If you did not insert the post yourself and dont know the total length of the seatpost you don't know how deep it goes. Perhaps this can be tested by feeling for the bottom of the seatpost by putting a long thin tool with a sort of hook in the end into the inside of the seatpost.
    – Mads Skjern
    Aug 8, 2014 at 21:42
  • Remember that if you cut of the part of the post which is outside the frame, and then fail in removing the rest with a hacksaw blade, then you are pretty stuck, and I don't see any solution but to discard the entire frame.
    – Mads Skjern
    Aug 8, 2014 at 21:44
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At the non-profit workshop, where I volunteer, we sometimes ream out the old Seatpost enough to stick in another, smaller-diameter Seatpost.

Especially if you don't care too much about aestetics and the seized seatpost reaches deep into the frame(at least 8-10cm, preferably more) this might be a viable option to just make the bike rideable again. If it is less, you might be able to saw a slice out of the old seatpost(would have to be all the way into the downtube of the frame) and the crush the compromised tube with vise-grips.

In my experience, seized seatpost and their removability often boil down to how much effort and time one is willing to invest.

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  • Good thought - one downside is older seat posts tend to be 25.4mm OD so finding one to fit inside that is unlikely.
    – Criggie ♦
    Aug 19, 2018 at 8:56
  • @Criggie: I'm not sure, that this claim: "[…]older seat posts tend to be 25.4mm OD[…]" stands in Germany. The old 25.4mm seatposts(the type that requires a guts clamp) that we admittedly see a fair share of, tend to be made of Steel, so much less prone to get so viciously stuck in a steel frame, than the, usually larger, alloy ones.
    – MTTI
    Aug 19, 2018 at 11:23
  • was more a comment around outer diametres only. Non profits tend to get older bikes and BSOs too.
    – Criggie ♦
    Aug 19, 2018 at 19:29
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I had this problem with a very stubborn seat post (turns out there was a wedge in it to keep the post in).

One thing that I tried was putting a blow torch on the frame to try and expand it a bit to get the post out and loosen any corrosion. I would only try this after WD40 has failed.

Disclaimer: this may damage your bike

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    Aluminum expands more than steel, so the nowadays recommended method is to plug the lower hole of the post and drip liquid nitrogen inside (might burn your skin! way cold!). Another option would be to empty a CO2 cartridge inside the post (or a lot of dry ice in alchohol) and THEN to wash the outside with boiling water. But never heat alone.
    – heltonbiker
    Oct 6, 2011 at 18:11
  • @heltonbiker - this method is described by Leonard Zinn
    – memnoch_proxy
    Jan 13, 2012 at 5:11
  • Heat alone can work, if you actually resort to enough of it to melt the aluminium. Obviously you need to be cautious, and your bike will need a repaint afterwards, but some framebuilders will do it: forum.ctc.org.uk/viewtopic.php?f=25&t=16716 yacf.co.uk/forum/index.php?topic=36893.msg771842#msg771842
    – armb
    Mar 20, 2013 at 12:23
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there is aerosol spray available at most hardware stores called PB Blaster it is much more effective when dealing with rust than WD=40

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  • -1. The asker's seatpost is aluminum alloy. So the asker is dealing with some form of oxidation or corrosion. Not with "rust" (iron oxide).
    – unforgettableidSupportsMonica
    Nov 19, 2013 at 23:14
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Try put your seatpost / saddle on the vise ( reverse the bike ) then rotate the frame for pulling out the seatpost, put WD-40 or other lubricant for before you do it....

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Using a small butane torch, heat the seat post till it breaks free from the frame.

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    This should be one of the very last resorts for a steel or titanium seatpost, but is useless for an aluminum seatpost as aluminum expands quicker than steel [ and one of the comments in a previous answer notes that the seatpost in this case is aluminum].
    – Batman
    Aug 10, 2014 at 2:14
  • It can work if you heat the frame and cool the post - if you heat the post that will also heat the frame, then you can try suddenly cooling the post. youtube.com/watch?v=wUzFj2K8Ti4
    – armb
    Jul 12, 2016 at 7:32

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