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Stuck seat post

Old 07-23-10, 07:37 PM
  #1  
Stealth'd
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Stuck seat post

I got a frame from a very confused friend that is a 27.0 seat post size, and there is a 27.2 THOMSON seat post in it. It's stuck in at least 4-5".

Is there a way to salvage either the frame or seat post....or both? I'm still flustered at how some kind of man would manage that.

And YES. I'm sure it's a 27.2 in a 27.0. I have the specs on the bike and the numbers on the seat post confirmed that it was a 27.2. (along with my micrometer)

I'm guessing a propane torch or something to the like.

Edit: and I'm upset that it's a thomson and not a no name post.
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Old 07-23-10, 07:52 PM
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If the post is physically rammed in there rather than just oxidized, there's not much you can do besides applying brute force.
Frankly, I don't see how it could get that far into the frame in the first place if it's a size too large.
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Old 07-23-10, 09:28 PM
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Put an old seat that you don't care about on the seatpost. Put penetrating oil like 3-in-1 oil in between the seatpost and the seattube. Then get a hammer and bang at the ends (nose or the back of the saddle) from side to side. If it moves, try pulling the seatpost out. Little by little repeat these steps. If it doesn't move, then put more oil in and let it sit overnight. Go back the next day and try again. Hope this helps.
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Old 07-23-10, 09:29 PM
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and whatever you do. Do NOT hammer the seat inwards towards the frame. You'll just make things worse.
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Old 07-23-10, 09:56 PM
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could you maybe flip the bike upside down(like your working on it), stand on the seat and pull up on the seat tube?
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Old 07-23-10, 09:57 PM
  #6  
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that sould give you a lot of pulling power, never had to try it, but in my mind it would work
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Old 07-23-10, 11:45 PM
  #7  
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Heating the post with a propane torch is not a good idea. Heating it will cause it to expand.
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Old 07-24-10, 12:17 AM
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+1 Grand Bois. Aluminum has a higher coeficient of expansion than steel, so heating it will make it tighter. If you have a vise mounted to something SOLID, you could carefully tighten the vise on the straight sides of the seat post (bike upside down), and use the bike for leverage--while lifting the frame, twist it slightly, and work the post out.
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Old 07-24-10, 08:50 AM
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If the above methods don't work, you could rig up a hydraulic press with a couple of car jacks and some pieces of 2x4 to slowly press the seat post out. You do have to be careful, since this method is able to exert enough force to break welds on the bike frame, but if they give first, I'm not sure the post would have been removable by any other method. You also need to be careful to use the same amount of force on both sides of the bike to avoid bending frame/post.
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Old 07-24-10, 10:06 AM
  #10  
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well if the seat height is ok for you dont mess with it haha, and as a +, nobody could steal your seat!
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Old 07-24-10, 10:56 AM
  #11  
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I'm with chadwebster. I had this exact same problem once. I removed the BB, shot a bunch of penetrating oil down (up?) the seat tube, let it sit overnight upside down. The next morning I mounted an old seat, stood on the seat (with the frame upside down, again), and twisted the frame. Came out no problem.
 
Old 07-24-10, 11:01 AM
  #12  
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Please don't use unpadded vise jaws on anything you want to keep. There is just no way to avoid badly scarring the surfaces of the metal at the best of times let alone in a case like this where you need to use a LOT of force.
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Old 07-24-10, 11:14 AM
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Originally Posted by myrridin View Post
If the above methods don't work, you could rig up a hydraulic press with a couple of car jacks and some pieces of 2x4 to slowly press the seat post out. You do have to be careful, since this method is able to exert enough force to break welds on the bike frame, but if they give first, I'm not sure the post would have been removable by any other method. You also need to be careful to use the same amount of force on both sides of the bike to avoid bending frame/post.
This might break the frame.

I would try the upside down -- stand on the seat -- twist the frame method. If that doesn't work, you're probably left with cutting off the post an inch above the frame and 'carefully' sawing a slot down the inside of the post. Then grab an end with pliers and twist it inward to break it loose. It's tricky to do.
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Old 07-24-10, 11:53 AM
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I'm going to use penetrating oil and invert the frame to try pulling it out. Then if that doesn't work, I think I'm going to cut the seatpost at the end of the tube and find a very long jigsaw bit and cut long slots down the seatpost pretty much like what rm-rf suggested.
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Old 07-24-10, 12:17 PM
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Originally Posted by badamsjr View Post
+1 Grand Bois. Aluminum has a higher coeficient of expansion than steel, so heating it will make it tighter.
Where does it say the bike is steel??? If the frame is alu and the post is alu, then heating the seat tube - NOT the post! - with a propane torch should cause it to expand more than the post. Otoh - goodbye Mr Paint! And you'll need to keep the heat way down to avoid interfering with any heat treatment the frame had.

This is what Sheldon Brown suggests:

https://www.sheldonbrown.com/stuck-seatposts.html

Btw, you might want ti read this -

https://road.cc/content/forum/14720-s...st-stuck-frame

A friend of mine who took a bike with a stuck seatpost into a bike shop in Cambridge was told by the owner that he wouldn't touch it, since he knew someone who had died attempting to remove a stuck seatpost!
- Not that I'm trying to put you off! (Also: HOW do you die removing a seatpost??)

Last edited by meanwhile; 07-24-10 at 12:22 PM.
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Old 07-24-10, 02:13 PM
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Oh it's okay I'll have a will written up shortly before I attempt this...


So the frame is Aluminum...and the seat post is aluminum....so If my thoughts are correct, heating won't do much good?
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Old 07-24-10, 06:21 PM
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What if you applied some serious cold to the post, then gentle (like, hair-dryer or low-setting heat gun) heat to the tube? _Might_ help make whatever above method you choose more effective.

Seems like the rotate-and-pull method has the most promise.

With the bottom bracket out, is the bb shell "open" where the bottom of the seat tube meets it? If so, you could drizzle more oil into the tube that way.
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Old 07-24-10, 06:30 PM
  #18  
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I am able to get most stuck posts out via using PB Blaster. I let it soak for a day or two. I install a junker seat on it, put the seat in my bench vise, and carefully rotate the frame. Note, you can damage the frame doing this, so be careful.

Out of a dozen stuck posts, this has worked 11 times. The 12th time is going to require cutting out the post.

I just removed one yesterday using the PB Blaster/bench vise method.

Note, this is with alloy posts in steel frames.
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Old 07-24-10, 11:56 PM
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Status: sitting in my garage soaking in my mystery penetrating oil. Seriously. It has gotten so many bolts off of my rusty car and it doesn't even have a label...<3<3

Trying to get it off tomorrow. Although I have a vise, I don't have an old seat. I get rid of the parts I don't use. I know, shame on me.
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Old 07-25-10, 12:34 AM
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If you MUST use the vise to hold the seat post then the best possible way to do it is to drill a hole in a scrap block of 2x4 that is a very close fit to the seat post. Then cut it along the axis of the hole so you have a set of saddle blocks to best grip the seat post when you clamp it all up in the vise. If this means riding your spare bike.... you DO have a spare bike, right?... to the hardware store to get a suitable size spade drill bit for wood that is fine. With jobs such as this the key is prep and more prep before the final deed is done so you avoid damage to expensive parts.
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Old 07-26-10, 06:33 AM
  #21  
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Originally Posted by Stealth'd View Post
Status: sitting in my garage soaking in my mystery penetrating oil. Seriously. It has gotten so many bolts off of my rusty car and it doesn't even have a label...<3<3

Trying to get it off tomorrow. Although I have a vise, I don't have an old seat. I get rid of the parts I don't use. I know, shame on me.
Your bike store will have "take off" seats, and might have some damaged ones really cheap.
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