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Stuck seatpost cost-benefit analysis

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Stuck seatpost cost-benefit analysis

Old 04-08-14, 01:47 AM
  #1  
Rest_assured
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Stuck seatpost cost-benefit analysis

Hi al,
Picked up a Kona Stuff for $50 that looks to be from about 2003, with the intentions of flipping it.
The bike is in pretty good condition, except the seatpost is stuck. With some effort, the post rotates in the frame, but will not go higher or lower (something I have never experienced before).
I have never gotten to the point that i need to consider using the hacksaw trick, but this seatpost really doesn't want to come out of the frame.
My question: how much time and energy goes into extracting the post with a hacksaw blade. It sounds... awful. I am tossing up between stripping the parts (alivio group, 1 deore hydraulic disc brake, Zokes (?) triple clamps) and ditching the frame, or putting the effort in to get the bastard out and sell the compete bike (probably for $300 +/- 20% in my market, with a further 50-100 to spend).
Cheers.
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Old 04-08-14, 06:26 AM
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If the seatpost rotates at all, then you are nowhere near needing a hacksaw. Apply a liberal dose of penetrating oil (PB Blaster, CRC Freeze Off, etc.) daily and keep working to loosen it up. Apply the penetrating oil from both ends of the seat tube (pull the BB, if you haven't already, to get access and keep it from getting soaked in penetrating oil). Ideally, clamp the post in a vise and twist the frame back and forth while pulling up with as much force as you can muster. A large pipe wrench (36" or more) can be an effective alternative if you don't have a vice (and don't plan to re-use the seatpost). Don't be afraid to put some force into it -- it's pretty amazing how much torque/tension a seat tube can handle.
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Old 04-08-14, 06:48 AM
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Yeah that was my thinking initially. On closer inspection I can see that the old owner has tried the vise trick, there are marks on the top of the seatpost.
Is there some likely cause of the problem that lets the seatpost rotate but not go up or down? I thought that was strange.
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Old 04-08-14, 07:46 AM
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if the seatpost is stuck
the bike is worthless to anyone except the 0.5% of the population who have exactly the right leg length

so i dont know how much it would be worth before or after
just that with the seatpost stuck it is worth much much less
the fifty dollars you paid is probably about right
regardless of what other work has been done to the bike
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Old 04-08-14, 07:49 AM
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A remote possibility but is the seatpost the type that uses an expander wedge (like a quill stem) to tighten in place? If so the wedge may be stuck and could be knocked loose by backing out the bolt and hitting it on the head with a hammer like you do to loosen a quill stem.
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Old 04-08-14, 07:54 AM
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Given that the seatpost is already marked up, I'd be inclined to just cut it. It's going to be quicker to hacksaw it, than it is to keep putting penetrating oil on it and waiting.

Hacksawing it out might take 15 minutes.

If you can save the seatpost, it would obviously be cheaper, so it's a question of time versus money.
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Old 04-08-14, 09:58 AM
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Any chance that a water bottle cage bolt is pushing into the seat post? Only thing that I could think of that might let a post rotate but not move vertically.
If there is room to get on it, an air impact chisel (zip gun) underneath the top of the post is supposed to work well. You can even drill a hole crosswise through the seat post, put a bar in the hole and then use the airgun against the bar.
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Old 04-08-14, 10:29 AM
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Originally Posted by merlinextraligh
Given that the seatpost is already marked up, I'd be inclined to just cut it. It's going to be quicker to hacksaw it, than it is to keep putting penetrating oil on it and waiting.

Hacksawing it out might take 15 minutes.

If you can save the seatpost, it would obviously be cheaper, so it's a question of time versus money.
15 minutes?! Not doubting you, but I'd sure like to know your trick. Last time I went down that road it took me the better part of four hours (and that was after dissolving a good portion of the post in sodium hydroxide).
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Old 04-08-14, 10:36 AM
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If it rotates, it will come out provided there isn't any oddness like a water bottle bolt sticking into it. You just need more strength. Strip the frame so there is no fork, no rear wheel and maybe remove cranks if they become an annoyance. Then have 2 big strong people pulling and twisting against the frame and seat.

I strip the frame just to make it easier to grab and move around.
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Old 04-08-14, 10:44 AM
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Originally Posted by Rest_assured
Yeah that was my thinking initially. On closer inspection I can see that the old owner has tried the vise trick, there are marks on the top of the seatpost.
Is there some likely cause of the problem that lets the seatpost rotate but not go up or down? I thought that was strange.
Corrosion burrs in the seat tube could have actually cut grooves in the seatpost during previous removal efforts. Moving within the established grooves would offer less resistance than trying to "cut" new ones. Even a small burr can really hang things up. I like the air hammer suggestion as the shock can be really effective for shattering the oxide residues.
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Old 04-08-14, 10:48 AM
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15 minutes doesn't seem out of line with the right tools. There are several "hand grips" made that will hold a blade and allow long, accurate strokes. I've used a reciprocating saw, carefully, slowly, in situations like this to do the majority of work-I then finish with a hand held blade. There are also hand "vises" that will hold the long, tough, blades designed for reciprocating saws rather than the usual hand saw blades. Good luck.
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Old 04-08-14, 11:22 AM
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Originally Posted by Kopsis
15 minutes?! Not doubting you, but I'd sure like to know your trick. Last time I went down that road it took me the better part of four hours (and that was after dissolving a good portion of the post in sodium hydroxide).
cut the top off close to the frame, that should take less than a minute.

Cut slot in the seatpost with a keyhole saw, maybe another couple minutes. Cut another slot, and remove piece. If it doesn't come out then, cut another slot or two until it does.
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Old 04-08-14, 05:33 PM
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Originally Posted by merlinextraligh
cut the top off close to the frame, that should take less than a minute.

Cut slot in the seatpost with a keyhole saw, maybe another couple minutes. Cut another slot, and remove piece. If it doesn't come out then, cut another slot or two until it does.
The 'hacksaw trick' as I interpreted it is to cut the post at about 2cm above the seat tube, and use a blade down into the post to cut through the post lengthways. The post can then be kind of bent and spiralled into itself and pulled out. If we are talking about the same thing, 15 minutes sounds like a no-brainer, but I was thinking it would be more like Kopsis' suggestion (4hrs+).
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Old 04-08-14, 06:06 PM
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No mount for drink bottle on the seat tube, and it's not a quill seat post btw.
Thanks for the help, everyone. I'll report back when I have reached a solution.
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Old 04-08-14, 06:10 PM
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Bench vise. Slide hammer. Air chisel. Recip saw (sawzall). It doesn't stand a chance. But how do all these posts and stems get stuck in the first place?
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Old 04-08-14, 06:15 PM
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Originally Posted by CroMo Mike
Bench vise. Slide hammer. Air chisel. Recip saw (sawzall). It doesn't stand a chance. But how do all these posts and stems get stuck in the first place?
Neglect and time.
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Old 04-08-14, 06:27 PM
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Originally Posted by bikemig
Neglect and time.
True, or somebody using the wrong size.
But neither of those causes seem to apply here, the bike seems to be relatively well cared for, and from what i can tell the post is the right size.
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Old 04-08-14, 06:34 PM
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Originally Posted by merlinextraligh
Given that the seatpost is already marked up, I'd be inclined to just cut it. It's going to be quicker to hacksaw it, than it is to keep putting penetrating oil on it and waiting.

Hacksawing it out might take 15 minutes.

If you can save the seatpost, it would obviously be cheaper, so it's a question of time versus money.
15 mins if there is only two inches of post
in the tube.
In my experince ya gotta cut two slots to get
it out. It is a thick strong tube and the curling it around
idea doesn't work.
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Old 04-08-14, 07:40 PM
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spin the post 90 degrees then take a hammer and knock it out.
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Old 04-08-14, 08:03 PM
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Originally Posted by reptilezs
spin the post 90 degrees then take a hammer and knock it out.
Can you expand on that a little bit please?
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Old 04-08-14, 09:07 PM
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Originally Posted by Kopsis
15 minutes?! Not doubting you, but I'd sure like to know your trick. Last time I went down that road it took me the better part of four hours (and that was after dissolving a good portion of the post in sodium hydroxide).
+1 on the 4 hours. That was my experience last summer. But I did get that sucker out.
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Old 04-08-14, 10:04 PM
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Originally Posted by Rest_assured
Can you expand on that a little bit please?
twist it so the nose is point 90 degress off of straight ahead, this brings the saddle clamp head out. now you have clearance to smash on it with a hammer
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Old 04-08-14, 10:13 PM
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It seems like the method you should use would depend upon what material the seatpost is made of, and how much seatpost (how many inches) is stuck in the seat tube.
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Old 04-08-14, 10:27 PM
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I've cut a piece of a broom handle in half lengthwise, glued in a hacksaw blade overhanging the edge about the thickness of the post. Worked like a charm compared with a handheld bare blade. Don't remember exact time, but closer to 15 minutes than 4 hours anyhow.
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Old 04-08-14, 10:36 PM
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Strip the bike, including the cranks. Invert the frame and fill the seat tube with penetrating oil. Let it soak for a while, then grab the seatpost in a bench vice. Spin the frame around while pushing it upward- it should "unthread" itself from the seatpost.

You'll want to clean up the inside of the seattube with a straight reamer before installing a new post.
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