Stuck seat post
 

Hey all!
I have an aluminum seat post stuck in a steel frame. WD-40 and muscle force have failed. The paint is of no concern, so I could apply a propane torch -- but I would have to be quick, since aluminum expands more than steel.
Thoughts?

WD-40 is a poor choice for penetrating into corrosion. Try some Kroil or PB Blaster, instead. search this forum for numerous stuck seat post discussions for more suggestions before trying something as drastic as a propane torch.

Put post in vice,use frame to twist it out.

If it's a nice frame you want to save,cut the post with a rotory file,collapse the post and remove.

Be real careful about cutting into the frame tubing.

If you want to try heat,get some beeswax( a bar or a candle) heat the tubing and melt some beeswax into the post.....beeswax is the best for removing rusted bolts and stuff.....Beeswax is the best rust penetrant made.Better than Kroil or PB Blaster.....by far! IF your using heat.

Use this to your advantage. Canned air can turned upside down to rapidly cool the post, might be enough to break it loose.

I plead guilty! Guilty of being the clueless rookie who posts a basic question that has already been answered a thousand times. And I even forgot about Sheldon Brown for a moment. I blame it on a skinned knuckle.

I am now reading up on it and will report the final result.

Well, I give up. At least for now. I was actually able to twist the post by clamping the saddle in the vise and wrestling with the frame. (I was replacing the saddle in the first place.) But then I took the saddle off -- and found the hammer marks. This post was hammered in, hard. The post is downright mushroomed on top. So this bicycle has only one saddle height. Maybe I'll return to it on a quiet winter day, and play with acid and dry ice. But I have 15 other bikes to tune up now.

Thanks guys! Hopefully I can contribute something on this forum eventually.

a friend of mine who is an aircraft mechanic had me mix up a 50-50 solution of acetone and automatic transmission fluid for loosening difficult nuts & bolts. The acetone wicks it's way into small spaces and carries the ATF with it. Let it sit for a few hours and then try to remove the post. An empty 3-in-one oil can is great for this. I have also used small syringes for tighter spots.

Ah yeah, acetone is very "thin". And I already use ATF for lots of things. I'll keep that in mind.

Oh, and I sold my beloved 1983 R100RT only a couple of years ago. Don't quite have the balance for motorcycle riding anymore. Love those "airheads"!

too bad, less balance simply means it's time for a sidecar rig.

since you got it to twist then you are almost free. use some penetrating oil then twist it with a pipe wrench and pull. if you can twist it 90 degrees then you can tap on the saddle clamp head with a hammer to drive it out.

Sand it down in the slot in the seat-post. Twist, sand, a little oil and repeat. It should loosen up some. If you can then pull it up even a little you can repeat until it comes free.

I just had to deal with this on a bike I just bought I was replacing the post and just needed to get it out so I ran my router through a small piece of wood just big enough to be seated on the top post and an extra jack that I use to split engine blocks and cranked it into the seat which was torqued to hell and it just lifted right up I would have used heat and dried ice if I didnt care for the paint

The only way it will twist is when I use the whole frame as a lever. I almost pulled the work bench over while twisting and pulling, but it will not budge lengthwise. And when I tried again using armstrong power on only the saddle, it would not twist at all. It is indeed strange that it will not move outward at all when it can be twisted, but the force needed to twist it is immense. I'll probably lay awake tonight trying to visualize the damage that would be caused by hammering the post in. Some people!

I'd bet they didn't even get it to the right height hammering it in...probably just "close enough" before giving up.

My guess is that the seat post was 0.2mm bigger than the correct size for the frame, but "it'll work"

since the post is stuck from brute force rather than corrosion the method of removal is a little different. you will need to drive the post back out by hammering on it the opposite way. you can also try a slide hammer attached to the saddle clamp hardware. the 90 degree trick works well in my experience

I am well familiar with the importance of the 0.2 mm differences! But of course, most regular citizens would have no idea. People! LOL

I like the slide hammer idea. I don't own one, but I can certainly build or borrow one.

Now, for a good laugh.... In my fitful sleep I considered cutting the frame in pieces so I could beat on the bottom of the post, then weld the frame back together! But of course, that would only compress and thicken the post -- and not be quite healthy for the frame. But brainstorming is fun.

Wut?

Wut?
I perceive it as placing a scissor jack between the frame and the saddle (or a purpose-made attachment). This could certainly generate a great deal of force, but I wonder if the force could be controlled -- that is, keeping the assembly together during the process, and directing the force in line with the post. It's just wild enough I might try it. Jaws Of Life anyone?

The way I would control the force was by using a piece of wood on the top frame tube but I removed a semi circle in that piece of wood to keep it from moving and just jacked up the poll using the seat I wish I took a picture would make it easy to understand.

I think I understand it. Your wood is the length of the top tube and the notch is against the steering tube. And I'm thinking the wood could be cut so the "pad" for the jack matches the angle of the seat tube. Might be a good idea to screw some plywood to the wood so as to keep it from rotating off the top tube -- in case the notch in front is not enough. My kind of Rube Goldberg solution! The force could be quite literally a ton.

Al post stuck in a steel frame? Ammonia is better than penetrating oil.

Any post forced/hammered into an old frame? I prolly wouldn't waste time on it.You can prolly get it out, but it'll take forever, and may leave a damaged frame anyway, as a reward for your troubles.

If it turns, it will come out. I have had one that turned and did not come out. It was a risky move, but I was convinced to pound it in about 3/4 of an inch, hoping to break loose whatever it was stuck on.

It worked.

Realize whatever anyone reports as the miracle aid, there are various degrees of "stuck", and do enough bikes, and you will find one where cutting it out is the only thing that works.

+1 WD40 is a waste of time.

Be careful about putting too much force on the frame while turning it. You can bend the frame that way (ask me how I know)... Big vise and a stable bench are a must!