My Turn
 

I knew the seatpost was stuck. But it was my town bike. Set up for me. I'm giving it away, to someone much smaller than me. He will likely sell it, also to a short person. We don't have PBlaster here. The best I can do is Evaporust.

Kerosene and Automatic transmission fluid is supposed to work as good or better than many penetrating oils. If they are available, it might be worth a try.

I believe that it is a 50/50 mix.

The 50/50 mix that I use is acetone and ATF. Works very well as a penetrant.

Is it a steel post or aluminum, if steel, your way is a penetrant or heat. If aluminum you could use lye but it could destroy the paint.

If it's really stuck and you don't care about the seat post.

I tried everything including a air hammer except the impact wrench idea of RJ's. I would have tried that too but had already gave up and cut the post off to try the lye. I ran out of lye so used a hacksaw blade. One side came loose and out of the bottom bracket shell after cutting it in pieces. The other half came out the top. If you don't give up it will come out.
https://cimg7.ibsrv.net/gimg/bikefor...7ea33d9c7f.jpg
Always grease your post!

I can't suggest any new magic formula for removing the seatpost.

Just a trick or two.

If the bicycle has waterbottle bosses on the seat tube, remove the screws, turn the bicycle upside down and inject your favorite formula into the holes.
If no bosses, remove the bottom bracket, turn it upside down and and pour a bit in that way.
If you have a compressor, fashion a flexible tube to a blow nozzle and blast the formula in that way.

Ok, I do have a secret weapon no one else has mentioned - Molybdenum disulfide(AKA Drislide)
Sorry, I don't have a photo, but I like the 4oz bottles with the long needle applicator.


This stuff penetrates like no other product I have ever used. Use small amount from the top, and if needed from the bottom,as mentioned above.
After applying and letting sit for a bit, take a rubber mallet and GENTLY tap the seatpost(if you tap frame you risk denting the tubes).

It sets up a vibration the helps this stuff move.
It may have to sit overnight for best penetration.

Best of luck.

Thanks for all the tips. The bike is a mid 90s Giant Yukon. It weighs a ton! I can't imagine damaging the frame via the bench vise method. I will look around for drislide, and try atf mix in the meantime. I am not yet ready to sacrifice a perfectly good alu seatpost.

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We have so doggone many of these seized saddle pillar threads it seems like we might be well served by having a sticky for them...
@cb400bill

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I've used a lot of different methods combined, and sometimes freezing the post with dry ice seemed to help it finally break free.

I had a stuck quill stem in my Pro Tour yesterday, and had already soaked it with PB Blaster from the bottom end and waited 24 hours, but still it wouldn't budge.

I decided to try a different approach, having used the propane torch on many of the bike's spoke nipples with much success.
So I blasted the quill with the torch for a few minutes, until smoke could be seen after the flame was removed for a moment.
The stem initially didn't budge, but after cooling for 5-6 minutes I tried again, and it cracked free with less force than I had applied before!!!
The stuck stem was holding me back from completing the refurb of the bike and using it on today's club ride in the hills, so I gave the torch a try and voila!
Highly recommended, though here one would obviously have to use more restraint with the heat, to spare the bike's paint! :thumb:

Everybody... today's text: I must re-grease my stem and seat post... today!

I'm a procrastinator. I'll do it...tomorrow.

Cutting an aluminum quill stem as we speak. Now that its cutoff I realized that none of my saw blades fit inside the narrow opening for the long expander bolt.

Do I need to cut a blade lengthwise? I asked at stores but no one has a blade that's small enough to fit.

Should I try drilling downwards to widen the hole?

'sawzall' blades usually have a tapered end. That might allow you to get started with the tapered end and then proceed farther down the post as you cut a slot.

Don't use lye. It's too dangerous.

Sorry that I didn't bring this up earlier, but I've now thought about why heating a stem works so well at loosening it's bond inside of the steerer tube, even as the aluminum part expands inside of the steel tube which expands less than the aluminum.

What actually happens is that the aluminum part lengthens in response to the heat, and because of the difference in length-wise expansion, the stem breaks itself free of much of the length of the corrosion bond, with perhaps only a finite length along the bond's length remaining stationary and thus still bonded.
I think that this explains why my Centurion Pro-Tour's stem broke free with so much less twisting torque after I had heated it but while it was still hot and expanded inside of the fork's steerer tube.

With your stem quill now cut off (to what length I don't know), is there still enough length protruding with which to apply heat and twisting force?
Perhaps two or three smoking-hot heating cycles (including dry ice after each heating) might allow a limited amount of torque to still break it free.

If it's near-flush with the end of the steerer, then I would first drill it to as large of a diameter as possible.
A 7/8" drill measures 22.225, which is likely no bigger than the steerer's ID. And the very outermost edge of the tip of the bit could be smoothed to prevent any possibility of the bit digging into the inside of the steerer. I don't really know what progression of drill sizes would be best to use, but the bits themselves will be quite expensive if you don't already have them.

Ok. Moments ago I mixed up some ATF and acetone, 50/50. I shot 15ml in through the bottle boss. Anybody have a guess as to when I should check it? Hopefully I didn't just fill the open end of the seat post.

I usually wait 24 hours before seeing if anything is freed up.

Just an idea on mitigating the danger of using lye.

This worked for me but might not work for you so please think carefully before following my lead. I used heavy winter clothing and gloves and eye protection.

I tried sawing out my stuck stem but once I got most of the sawing done I wanted to spray in some more PB blaster to assist before twisting. I tapped in a small slot screwdriver where the stem wouldn't peel away from the steerer tube and the blade chipped the threads of the steerer. I decided to try the lye to prevent me inadvertently causing further damage. I would be concerned about the lye damaging the paint of a seat tube. I wasn’t concerned about the steerer tube as it's usually out of sight and if paint were damaged the touch up paint won't be seen. Ultimately there was no damage to my paint but every bike company used different paint so your results may vary. I was also very nervous of splatter from a lye solution.

I waited until after a cold night (-14c or -7f). In my backyard I have a spot where we had a garden that is now filled in with fine crush where I have to install some bricks. I put down a piece of old plywood as a base. I added about two large spoonfuls of lye powder into a plastic juice bottle and added about two cups of cold tap water. I positioned the forks with the stuck stem in the plastic bottle and stood back. There was almost no reaction so I removed the forks and added a bit more lye powder and then the forks and repeated that until a reaction started. At first it was a very minor bubbling, but as the day came and the sun warmed the air the reaction began to speed up. By now there was about 200gr (just shy of half a pound) of lye crystals in 2 cups of water which is far stronger a mixture than the online recipes I'd seen suggesting 200gr to a liter (about 3 cups) of water.

The dimple in the snow on the left is where the bottle sat for the first 10 minutes. Melting snow around the jug only occured between the 2nd and 3rd times I checked to see if there was any movement. Even then there was a very small amount of bubbling in the solution. After about 10 minutes I removed the forks and inserted a large steel screwdriver and tapped the wedge. The stem parts remained stuck so forks went back in the bottle. I tried again 10 minutes later, and again 10 minutes after that.

https://cimg4.ibsrv.net/gimg/bikefor...667eba31aa.jpg


At that point I used a hammer against the screwdriver and the stem began to move out. After a few hard strikes, the stem slipped out. I immediately rinsed off the entire piece, inside and outside of the steer tube and the forks as well in case the lye had splattered on the forks and in case the lye is bad on chrome. At that time it was still around -5c or 23f and the outside of the plastic bottle was only mildly warm (similar to the heat felt when holding a takeout coffee cup). I didn't photo the remains of the stem but the part of the stem that had been in direct contact with the lye solution (including inside the stem) was very melted but the last two inches which were deep inside the steerer tube showed almost no effect from the solution and showed no sign of any of the penetrants. I had used (PB Blaster and ATF/Acetone mixture). Based on that I would assume that Jobst Brandt was correct when he said that penetrants can't always pass between a stuck stem and the steerer tube due to the corrosion expanding and blocking the way On a whim I inserted the remaining piece of the stem into the bottle but I moved the bottle directly onto the crush. I wanted to see how much stem would be dissolved. Adding the remaining stem was a bad idea as the day was warming rapidly.

I went to my garage and forced rags through the inside of the steerer tube to clean out any debris. I will still have to polish the inside of the tube to ensure there is nothing to catch the next stem, when I rebuild the bike.

After about 10 minutes I returned to the backyard to clean up. By now the sun was directly shining on the brick wall behind the plastic bottle. While the air was still below 0c or 32f the wall and the lye solution had warmed up considerably. The heat generated by the solution had melted a hole in the bottle and the solution had bubbled out onto the crush. Just a sliver remained of the aluminum stem.

In retrospect - I should have chosen a stronger bottle and I should have placed the bottle of solution in a large pail with a half inch of water already in it at the very start. As soon as the stem was free I should have immediately added more cold water into the bottle to weight it down and prevent it tipping over and to water down the solution. I should then have added more water to the outer pail to keep it cool. I should not have continued to soak the remainder of the stem.

I would not try this solution in warmer weather as it may react too fast but I would do it again in cold weather as the low temperature seemed to slow the reaction considerably. I would also consider doing it just at dusk to keep solar heat out of the equation and I would always do this outside!

I've cut a blade in half lengthwise with tin snips to fit small areas.