Getting a seatpost unstuck

[spankthepow]

So I've got this old Schwinn tandem that my wife and I got as a wedding present a few years ago. The seatpost unfortunately broke and now I can't seem to get it out to replace it. I sprayed some PB blaster around it, but it still won't budge...any ideas?


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[mcski]

Sawzall. Gently

[rideit]

Or just a hacksaw blade if a sawzall blade is too wide.

[toast2266]

If all else fails, find someone with an adjustable seat tube reamer.

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[Dantheman]

Heat the seat tube a bit with a torch. The seat tube will expand more than broken post and likely (maybe, possibly) free it. Pretty common method for freeing seized stuff like this. Or keep spraying it with penetrating oil and lightly tapping with a hammer, though could take a few days if it will work at all. If there's a metal fab shop near you they might have some tools/ideas.

[Dee Hubbs]

As mentioned above a hacksaw blade on a keyhole saw. One maybe two cuts down the inside length of the seaport should separate it.

[simple]

I've been down this road before. Ruined a really nice steel frame. I tried everything I could. Even a reamer didn't work as the post was thin and fused to the frame.

This is how bicycles die. Sorry. You could cut the tube out and weld a new one in. Then paint the whole frame a new color.

[GeezerSteve]

Steel post in a steel frame. Somebody can get that out. In my shop, I'd bore it out with my vertical mill. If I didn't have a mill, I'd likely use a Sawzall with a fine thin kerf metal blade. The idea is to cut make 2 full length vertical cuts from the inside, remove a section and then start to peel what's left.

Those old Schwinn seat posts are mild steel, easy to cut.

Did you allow the PB Blaster a couple days to penetrate? Penetrating oil usually worked for seized steel post in steel frame in my shop rat days, but if often took a few days.

Heat might do the trick but at the risk of ruining the paint.

I don't get how a reamer would work to get that out.

[El Chupacabra]

How much post is left inside the frame?

One tip I've heard frequently (but not tried personally) is to remove the bottom bracket, invert the bike, then pour penetrating fluid/ rust break-free/ Coca-Cola down inside the seat tube -- to let it sit up against the rust and do its work. With an open-end seatpost like that one, you'd have to plug it first.

[toast2266]

I don't get how a reamer would work to get that out.

It's nothing magical - stick the reamer in the seatpost. Remove metal. Adjust reamer. Remove more metal. Keep going until post is thin enough to collapse. It takes a long time.


That aside, if the inside of the seatpost is in ok shape, you might be able to just measure the ID of the post, cut a slot in it, and buy a new seatpost that'd fit inside your new secondary seat tube. Not very elegant, but maybe ok given the application.



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[GeezerSteve]

It's nothing magical - stick the reamer in the seatpost. Remove metal. Adjust reamer. Remove more metal. Keep going until post is thin enough to collapse. It takes a long time.

Uh, yeah, I know how a seat post reamer works, having used one many times, including 2 days ago to dress a newly built frame. It would take a few hundred hours to remove that stuck seatpost with a reamer a cunt hair at a time. Reamers are designed to remove a fraction of a millimeter at a time, and it takes alot of effort just to do that.

If you want to ream lots of material, and you aren't tooled up to bore, abrasives is the way to go, more specifically in this case a cartridge roll on a die grinder, finished with a bore polisher. That'd take an hour or so with the right setup.

Re placing a new post inside the ID of that post, note that's the old Schwinn 1" (25.4) post, as skinny as seat posts get.

[teledad]

Might be able to find an old 7/8" (22.2mm) BMX post, with the separate seat clamp.

[Beaver]

Star nut and a dent puller (slide hammer)? Attach the star nut to the dent puller, stuff it down the seat post then start pounding the puller up. You might get somewhere or you might just bend the star nut backwards. Make sure your star nut doesn't go through the post and hook up with your frame.

[spankthepow]

Thanks for the ideas all...

The PB blaster has been in there for about 24hours. I'm going to take the tap-spray-tap approach for the next day or so. If that doesn't work, sounds like the sawzall is my next best option.


I'll keep you all posted.

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[spankthepow]

How much post is left inside the frame?

No idea...I can't even get the other seatpost out all the way. It is definitely over 350mm thou.


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[grskier]

Star nut and a dent puller (slide hammer)? Attach the star nut to the dent puller, stuff it down the seat post then start pounding the puller up. You might get somewhere or you might just bend the star nut backwards. Make sure your star nut doesn't go through the post and hook up with your frame.

This was the idea I had essentially... hooking it and slide hammer it out after that rust break free has a day or two to penetrate....

[toast2266]

Uh, yeah, I know how a seat post reamer works

Uh, congratulations?

Re placing a new post inside the ID of that post, note that's the old Schwinn 1" (25.4) post, as skinny as seat posts get.

There are many easily available seatposts in sub 1" diameters. But since you're such a fucking encyclopedia of bike knowledge, we'll ignore that so you can be right.

But no disagreement that a post within the post is a shitty option.

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[detrusor]

Back in my shop days I took a ciocc san cristobal frame with a stuck campy post to a machine shop as a last resort. Tried everything else in the shop bag of tricks to no avail. Hour later it was done, 27.2 post fit perfectly.

If the suggested stuff doesn’t work try my last resort.


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[t-the-east]

That bike is gonna make you guys argue. Good luck with the seat post


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[JerseyDave]

AMMONIA! It's a chemical bond. It's dissolved by ammonia! Saved my buddies Balfa Minutman after he "Tried everything".
Check number 9!
http://sheldonbrown.com/stuck-seatposts.html

[GeezerSteve]

AMMONIA! It's a chemical bond. It's dissolved by ammonia! Saved my buddies Balfa Minutman after he "Tried everything".
Check number 9!
http://sheldonbrown.com/stuck-seatposts.html

NH3 works for Al alloy post in steel frame, but OP has steel post in steel frame. Sheldon's #8 (penetrating oil for steel in steel)

[shirk]

Make a duct tape handle on a hacksaw blade so it looks like a prison shiv and cut a 3-4 vertical cuts in the post. Peel out the stripes.

Hit it with an adjustable reamer after to clean up the corrosion on the inside of the seat tube.

[jackattack]

Copious pb blaster, a slide hammer and time.

You should be able to rent a slide hammer from your local auto parts store. They’re usually free with deposit.

[Jethro]

I’m going to also recommend the slide hammer. You are going to mar the frame trying to cut it out

Last week I tried to remove a drill chuck. Nothing was working. Heat, PB blaster, nothing could get it to budge. I put it in the freezer for an hour and then briefly hit it with a torch. Cold spindle and hot exterior and it spun right off

You could chill it inside with dry ice and then give the outside a quick once over with the torch. The outside might expand while the inside contracts. It’s worth a shot. Just don’t try to cut it out with a sawzall

[grskier]

So, yeah, did you get this thing out yet?