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Old 07-11-09, 10:20 PM   #1
TheCappucinoKid
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Any advice for a really stuck seatpost?

My friend has a great old classic black city bike in great condition, but can't ride it comfortably because the seat is too high so I tried to unstick it.... I tried prying the top of the seat tube open with a screwdriver (where the seatpost bolt is located), and then I managed to bang a screwdriver all around the seat post, a few mm deep. Then I sprayed WD40 liberally into all the cracks and openings that I could. Yet despite thinking i made progress, I still couldn't get the #"$ post to budge, even forcing it to turn hard as I could with pliers. The seatpost is obviously stuck by corrosion, as I could not remove the seat either, on account of the seatpost bolt fixed by rust. I did however manage to break the seat off, unwittingly, by trying to bang on the side of the seatpost with a hammer (I caused a crack at the top of the seatpost). So now i have a bike with a seatpost that won't budge, and a seat that moves too much. IOW, the bike is completely unuseable, at present.

The seatpost is just a tube, there,s no built-in clamp. Does this mean curtains for this classic bike, or is there a way to save it? If its impossible to get the seatpost out of the seat tube, what if I get someone to saw off the seatpost at the top of the seat tube... is there a seatpost made that is narrow enough to fit inside another seatpost which is inside the seat tube?
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Old 07-11-09, 10:33 PM   #2
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Hi, Cap!

You need to try these methods first:
http://sheldonbrown.com/stuck-seatposts.html

One thing not mentioned in Sheldon's article: for destructive removal, you can remove the wheels from the bike, clamp the remnants of the seatpost in a sturdy bench vice, and use the frame for leverage for twisting. Been there, done that.
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Old 07-11-09, 10:36 PM   #3
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WD-40 is good, but there's anti-seize which is better.

See if you can clamp the bike well somehow. A repair stand is best. Then:

- put in anti-seize
- let it soak an hour
- make sure the seat is clamped very well to the seatpost
- turn the bike upside down, in the clamp or repair stand or improvised setup
- bang on the seat with a rubber mallet

If that doesn't work, put in more anti-seize and wait overnight. Repeat the above procedure.
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Old 07-11-09, 11:33 PM   #4
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best way to remove a stuck seatpost is by using the search function before starting a new thread.

and a hacksaw.
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Old 07-12-09, 06:25 AM   #5
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+1 Search and PB Blaster to start. Depending how stuck it really is, freeing it up can get pretty involved.
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Old 07-12-09, 07:08 PM   #6
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As stated already,one good way is to clamp the seat post in a vise, remove the wheels from the frame and use the frame itself to provide leverage. You'll wreck the post but it will probably come out. Done it before myself.
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Old 07-12-09, 08:25 PM   #7
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PB Blaster
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Old 07-13-09, 06:15 AM   #8
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I've answered this question in detail twice this summer. Do a search.
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Old 07-13-09, 06:56 AM   #9
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+1. This comes up at least once a month. Plenty of good advice out there.
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Old 07-13-09, 07:16 AM   #10
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But one that probably wasn't covered, when all the above, including the dry ice in a quart plastic bottle wrapped around the seat tube to allow the aluminum post to contract at a different rate then the steel frame, method doesn't work.

Rent/use a Sawzall type saw, steel blade, cutting off the seat post about 1 inch above the seat tube.

Then VERY CAREFULLY cut the inner wall of the post until you free the post, "taking care" to not cut into the seat tube.

Really. I had to do this once and it does work, but is the absolutely the last resort.

Steve B.
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Old 07-13-09, 09:01 AM   #11
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But one that probably wasn't covered, when all the above, including the dry ice in a quart plastic bottle wrapped around the seat tube to allow the aluminum post to contract at a different rate then the steel frame, method doesn't work.

Rent/use a Sawzall type saw, steel blade, cutting off the seat post about 1 inch above the seat tube.

Then VERY CAREFULLY cut the inner wall of the post until you free the post, "taking care" to not cut into the seat tube.

Really. I had to do this once and it does work, but is the absolutely the last resort.

Steve B.
Thanks for the suggestions. I believe this is Sheldon Brown's last resort. But it appears the steel seat post is "cold welded" to the inside of the steel seat tube (by rust), all the way down its length. If this, as I believe may be the case, wouldn't this method not work because it doesn't go down into the seat tube far enough?
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Old 07-13-09, 09:42 AM   #12
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If you have a seatpost with very thick walls (mine had a tiny hole in the center, but the rest was all aluminum), you're bummed. Search and pray and think about getting a different bike.
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Old 07-13-09, 01:46 PM   #13
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No, the seatpost does not have thick walls and is not aluminum. It is steel, as is the seat tube and rest of this old bike.
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Old 07-13-09, 02:16 PM   #14
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Sheldon Brown! PB Blaster!! More importantly....SLOW DOWN!!! WD-40 is not a penatrating fluid!!!! That said as I have asked less than captivating questions.....

My experience. Take out bottom bracket so you can spray PB Blaster down (the bike's up) seat tube. Do this every day or 12 hours while it is in some sort of holder upside down. Let it work for a week if you must...or longer. Penatrating fluid will get there eventually. One more tip I was taught. The fluid gets into the "seam" a bit faster with little tapping every time you walk by. Suggest tapping on the seat post up while the frame is upside down. Vibration helps it work in. You are not trying to force movement, just VIBRATE. Read, hit it gently! And yes, you may tap and spray PB for a week+ but it will work free. Done this on old (1914) engines left outside as well as bottom brackets of nice old bikes that shops toss in the trash.

Good luck...and yes, use the search even more liberally than PB Blaster
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Old 07-13-09, 08:03 PM   #15
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No, the seatpost does not have thick walls and is not aluminum. It is steel, as is the seat tube and rest of this old bike.
At this point you have to ask yourself, even if you get the steel seat post out of the seat tube, in what condition is the frame ?, and can you then use an aluminum seat post ?, will it fit ?, is there too much corrosion and will you be able to clean out the seat tube ?.

Maybe think about a new used frame.

SB
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Old 07-13-09, 11:04 PM   #16
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Originally Posted by Lightingguy View Post
At this point you have to ask yourself, even if you get the steel seat post out of the seat tube, in what condition is the frame ?, and can you then use an aluminum seat post ?, will it fit ?, is there too much corrosion and will you be able to clean out the seat tube ?.

Maybe think about a new used frame.

SB
Good bike shops will have measuring tools, adjustable reamers, and an assortment of seatposts to fit. Aluminum seatposts vary in increments of 0.2mm, so finding a good fit is imperative.
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