Originally Posted by
Headpost
Originally Posted by joeswamp
These pictures frighten me. Did you soak the seatpost in anything or try to freeze it before attempting to get it out?
I have a stuck seatpost in an old bike I really like, but since the seatpost is at about the right height I haven't done anything about it. It's been stuck since I got the bike a few years ago.
At some point I will attempt to free it up. My plan will be:
1) Repeatedly soak for a month or so in Kroil.
2) Freeze the seatpost/top of frame with salt/ice in bags (or maybe dry ice) for a few hours
3) Clamp a large hardwood clamp around the post and attach a 10lb slide hammer
4) Wrap a towel soaked in boiling water around the seat tube (to quickly heat the tube relative to the post) and start banging away with the slide hammer
I'm hoping I can save the post and frame. I hate the idea of twisting the post to free it up, as frames aren't really designed to take forces like that. Most corrosion is brittle so any sharp impacts you can put on the post should help to break it free.
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Is this considered best practice or is there something else I should do?I'm in pretty much the same situation. If I ever get brave enough, my plan is to go with the "saw" method shown above.
If it is an aluminum alloy post in a steel frame, you can also try soaking it in ammonia. Over time, aluminum can chemically bond to steel if there's enough humidity. Ammonia (hopefully) dissolves the bond, without damaging the post and frame.
But, hope is a fickle mistress.
A Trek Elance 310 I build had sat outside for several years. The post was STUCK.
I soaked it in ammonia for a week, it didn't loosen up.
I tried thermal cycling - alternating passes with a heat gun and an ice bath, it didn't loosen up.
I tried soaking it in PB Blaster for a week, it didn't loosen up.
I tried clamping on an old stem and fork, to use as a lever. It didn't loosen up, and I stopped before I bent or broke my frame. I very easily could have pretzled my frame like Sloar did.
I cut the top of it off, and took a hacksaw blade and cut a slit vertically down the length of the post from the inside. It didn't loosen up.
Keep in mind these were all ways of loosening up posts that had worked for me in the past.
I cut 6 more slits vertically down the length of the post, it didn't loosen up.
I snapped the top of the post off attempting to fold the slivers of the post in on themselves.
So here's the post with slits cut in it, and not able to make it break loose from the seat tube:
I figured I should google for other ideas before taking the frame to a machine shop to try to have it drilled out.
I found the following v
(cue sounds of harps playing, and the clouds parting to allow a shaft of sun to gently bathe my frame in mellow golden light)
So I plugged up the bottom of the seat tube with silicone caulking - above where it meets the bottom bracket. I let the silicone cure for a week.
I bought a container of 100% lye crystals from Lowe's, it was $12.
I used gloves, safety goggles, and long sleeve shirts.
Do NOT fool around with lye, it will happily turn your skin, muscle, and fat into soap, leaving a nice crater where your exposed body parts used to be.
I used an old plastic measuring cup and put 500ml lukewarm water in it, then 4 capfuls of lye crystals.
DO NOT use hot water for this.
SLOWLY and CAREFULLY and GENTLY pour the crystals into the lid, and then GENTLY pour them into the water. GENTLY stir the crystals after each pour - you do not want to mix a larger volume of the crystals with water.
SLOWLY and CAREFULLY and GENTLY pour the lye solution into the seatpost. It will start bubbling away like one of those 'mudpot' geysers in Yellowstone. Let it sit for a few hours.
Carefully dump the sludge out and test if you can remove the post. If you can, rinse everything THOROUGHLY and congratulate yourself. Otherwise, prepare another batch of solution and repeat the process.
Mine took 1 and a half containers of crystals over 4 days.
Remnants of post after an invigorating lye spa treatment:
The lye solution will attack paint and any aluminum it comes in contact with. In my case, it bubbled over where the seat stays join the seat tube, and also down the back of the seat tube. This caused my paint to either get discolored / scorched looking, or be peeled away.