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Stuck Seatpost

Old 07-17-14, 12:07 PM
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blacky94
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Stuck Seatpost

So, I recently bought a used frame an forgot to check whether or not the seatpost was stuck Turned out it was stuck, but only about two or three centimeters too low. At first I was okay with it but over time it bugged me, so I decided to cut it out. Well, today I started only to see this:





The seatpost is stuck about 20cm in the seattube and I have absolutely no idea how to get it out. I tried the usual stuff like heating the frame and putting the seatpost in a vise and turning the frame, but nothing helped. Any ideas on how to get it out there?
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Old 07-17-14, 12:09 PM
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arex
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Soaked it in Liquid Wrench or anything?
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Old 07-17-14, 12:11 PM
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WD40, a few times..

Last edited by blacky94; 07-17-14 at 12:16 PM.
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Old 07-17-14, 12:20 PM
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You and a thousand prior posters, You Should have removed & greased the post/inside the seat tube occasionally..

get out the hacksaw blade and start sawing out segments of the aluminum seat post from the inside out..

looks like a thick one , it will take a while ..
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Old 07-17-14, 12:26 PM
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I never had a problem with any of my other bikes, because I lube everything. But I bought this one used and forgot to check..

That was my initial plan, but the hacksawblade is too wide and doesnt fit in the seatpost. And I don't have a 20cm long metal drill bit, which are by the way pretty expensive..
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Old 07-17-14, 12:26 PM
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Kroll penetrating oil soaked down through from the top of the tube, a lot of it, several days soak in, secure the frame very secure is should not budge when the next step occures, a 16 inch pipe wrench around the post, 2 lb sledge whack the pipewrench hard to break it loose,

most time a hard jar with a heavy hammer will help break anything loose better than just pressure
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Old 07-17-14, 12:35 PM
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Originally Posted by blacky94 View Post
. . . At first I was okay with it but over time it bugged me, so I decided to cut it out. . .
I've never had this problem so I'm curious: how does sawing off most of the exposed seat post make it easier to remove?
I bet it bugs you a lot more now.
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Old 07-17-14, 12:38 PM
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Drill it out until you can fit a hacksaw blade? Grind the back of a hacksaw blade until it will start? Use a reciprocating saw with a narrower blade to get a slot started? That has to be near the seat, the tube can't be that thick all the way down. Bad news if so, lots of seat post in there. But there will be a way.
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Old 07-17-14, 12:46 PM
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Originally Posted by AnkleWork View Post
I've never had this problem so I'm curious: how does sawing off most of the exposed seat post make it easier to remove?
Well, the problem was that it was not moving at all. So I figured I'll make a cut all the way down the seatpost to loosen it. And since the seat clamp and post were made from one piece, I couldn't cut it. That's why I cut the seatpost.


Originally Posted by howellhandmade View Post
Drill it out until you can fit a hacksaw blade? Grind the back of a hacksaw blade until it will start? Use a reciprocating saw with a narrower blade to get a slot started? That has to be near the seat, the tube can't be that thick all the way down. Bad news if so, lots of seat post in there. But there will be a way.
There are some good ideas, thanks! And I really really hope it's not that thick all the way down..
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Old 07-17-14, 12:50 PM
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cheaper seat posts use lower strength metal , but a lot of it.. Good Luck ..
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Old 07-17-14, 03:49 PM
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Originally Posted by blacky94 View Post
And I really really hope it's not that thick all the way down..
I don't think you'll have much luck with penetrating oil because at this point it doesn't look like you have enough exposed post to get the kind of grip you'll need to break it loose. The walls will thin out further down, but you may need to drill a good 4 - 6" before it widens enough for a standard hacksaw blade. The bad news is that you may have enough length inside the seat tube that a hacksaw blade isn't long enough to reach the far end.
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Old 07-18-14, 04:13 AM
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Originally Posted by blacky94 View Post
That was my initial plan, but the hacksawblade is too wide and doesnt fit in the seatpost. And I don't have a 20cm long metal drill bit, which are by the way pretty expensive..
If the frame is steel and you don't mind re-painting/powder coating, you 'can' remove the seat post with caustic soda. I have done this myself. It can be very dangerous but if you take the correct precautions it will work. Loads of video on youtube showing how it's done. Gloves, eye protection and suitable clothes are essential as well as doing it in a well ventilated area (the chemical reaction is quite fierce and produces hydrogen gas).

My seat post looked exactly like yours when I cut it off. Way too thick to get a blade down that far.

Good luck and be careful if you decide to go for it. No matter how careful you are it's bound to damage the paint somewhere.

EDIT: !!! Don't go anywhere near caustic soda if your frame is Aluminum !!!

Last edited by Teflon Shoulder; 07-18-14 at 04:51 AM.
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Old 07-18-14, 04:43 AM
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I think I'll just try it with a thinner blade to get started and then move on to a normal hacksaw blade. And if everything else fails I might try the caustic soda even though it doesn't sound like much fun
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Old 07-18-14, 07:22 AM
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I would not even try unless it's some rare frame in otherwise excellent condition. As you did not check for the seatpost you might want to now check that the rear triangle and fork are straight before putting a lot of time into it. If it were me I'd just toss the frame and chalk up to a lesson learned.
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Old 07-18-14, 08:44 AM
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I'm curious as to why you cut it off, instead of trying Kroil and a pipe wrench and turn it. Seems like that limits your options.

I'm a hack. What do I know?
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Old 07-18-14, 08:51 AM
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A milder "solvent", still assuming it's not an aluminum frame, is ammonia. Soak the joint with it and remove the bottom bracket, invert the frame and pour it in from the bottom of the seat tube.
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Old 07-18-14, 09:06 AM
  #17  
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Observation and question for the posters. The pictures shows a lugged frame. Were there any lugged aluminum frames? I know about Alan and Raleigh Technium.

Doesn't the presence of lugs make it pretty certain it is a steel frame of some sort?
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Old 07-18-14, 09:23 AM
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Originally Posted by jsharr View Post
Observation and question for the posters. The pictures shows a lugged frame. Were there any lugged aluminum frames? I know about Alan and Raleigh Technium.

Doesn't the presence of lugs make it pretty certain it is a steel frame of some sort?
Good point. I'd seen the lugs but added the comment about aluminum frames when sufficient time had passed for me to forget (about 5 minutes).

I'd ridden the frame I used caustic soda for 25 years and wanted to keep it. If I wasn't so attached I probably wouldn't have bothered. Buying the caustic soda, time and a repaint could well mean that it's cheaper to buy another frame.

Going the Caustic route is really quite fun and I probably made it sound worse than it is ...but it is potentially very dangerous. Think about what you're doing, is the work really worth it and only attempt it if you're confident in your abilities. It worked out well for me but I will probably never have call to want to do it again, too many cheap bikes to replace frames with.
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Old 07-18-14, 09:58 AM
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the walls are thick enough to grind some wrench flats

then get two wrenches that fit
and two cheater bars
and twist the post free
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Old 07-18-14, 10:07 AM
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Another method - pull it out - no dangerous chemicals

Strip the frame down, remove everything, most importantly the bottom bracket.

Take the frame to Home Depot, Lowes or similar; to get the correct sized parts.
* threaded rod, heavy duty nuts and heavy duty washers. The nuts have to fit up the seat tube and not through the hole in the seat post. The largest that will fit.
* cast steel gas pipe, the inner diameter just slightly larger than the outer diameter of the seat tube - you are going to pull the seat tube into the pipe. A 3" to 6" section is about right.
* cast steel end cap/reducer that threads onto the pipe above, and has a hole thru it fractionally larger than diameter of the threaded rod.
* high pressure grease.
* Red Loctite or equivalent thread locker. OPTIONAL

Method:

* Run a nut on to the threaded shaft - a couple of inches.
* Put two more nuts on the same end of the shaft, jam them together - apply thread locker (optional).
* From the other end of the shaft, drop on some washers alternating them so that some are rounded face to rounded face, some are sharp to sharp.
* next comes the gas pipe end and gas pipe.
* lay the frame horizontal, push threaded rod down the seat post, until it is visible at the BB.
* install nut thru BB opening on to the shaft - the further the better.
* grease the washers and the threaded shaft at the top near the gas pipe.
* using two wrenches - one on the nuts jammed together to prevent the threaded rod from turning, the other on the loose nut above the washers; turn the loose nut to pull the threaded rod up away from the BB. Lubricate the threads liberally. The rod, rotating nut and washers will get HOT.

Using ½-13 threaded rod and nuts, this will exert several tons of force.

I pulled a seat post out of lugged Trek 950 frame that someone had epoxied the seat post in place using this method.

I tried all the traditional methods - with a strong helper, and even dry ice. The hack saw method was not working - and would not work with the epoxy in there.
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Old 07-18-14, 10:18 AM
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heat the frame, chill the post. 1 expands , the other contracts ..
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Old 07-18-14, 10:18 AM
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Originally Posted by Wilfred Laurier View Post
the walls are thick enough to grind some wrench flats

then get two wrenches that fit
and two cheater bars
and twist the post free
An idea of excellence
A bolt turn it into
Then rotate relentless
A task impromtu
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Old 07-18-14, 10:23 AM
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Originally Posted by SquidPuppet View Post
An idea of excellence
A bolt turn it into
Then rotate relentless
A task impromtu
removing a post
can be quite a task
but its one of the most
common things a shops asked
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Old 07-18-14, 10:39 AM
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Originally Posted by Teflon Shoulder View Post
Going the Caustic route is really quite fun and I probably made it sound worse than it is ...
No you didn't. Though effective, there are a host of dangers with this approach. Just mixing the NaOH crystals with water is an exothermic reaction that can produce enough heat to produce severe burns and/or shatter/melt the container. The solution itself (at sufficient concentrations for this job) will produce severe chemical burns on contact with skin. The reaction with Al gives off explosive hydrogen gas, large amounts of heat, and leaves you with a sodium + aluminate slurry that you need to find a way to safely catch and dispose of.

I have used this method successfully and without incident, but I strongly advise that anyone considering it do plenty of research into the chemistry involved and the appropriate safety precautions.
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Old 07-18-14, 10:50 AM
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If the OP put the seat post in a vise and turned the frame there is nothing that will provide more leverage. Adding heat did not help, and using a true penetrating liquid probably would not have helped much either - though that should have been tried before cutting off the post.
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