Foolproof seized seatpost extractor tool
 

RJ, eat your heart out...


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It’s worse than it looks...there are bits of aluminum stuck in the seat tube...

What was the _process_? Did you just use the wood structure as a massive lever and twist/rotate? There are some frames that would buckle under that amount of leverage.

Yep. Used the frame as the lever and the wood as a vice. Had two 2X4s running parallel to the 2X6s holding the seat down, then a set of cross bars perpendicular on top that were clamped to minimize twisting other than rotational and upward...those I removed before thinking to take the picture unfortunately...the clamped wood also allowed me too lift upward at the same time while gently twisting after the initial pop...

In fairness I had soaked in evaporust first. Then the last two days PB Blaster just to have some viscosity!

...it was that or the other crappy options.

On the other hand...
 

How are these posts attached to the top...it looks like two pieces.

...and based on the other handlebar thread, is this safe to reuse after sanding and repolishing?


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Minor marbling?
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Two pieces or deceptive?

It looks to me like you broke the press fit between the clamp and the post. I wouldn't ride it.

My dad would approve of our tool, "Don't use force, Get a bigger hammer." In this case, a sledge hammer.

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...personally, I would not reuse that post.

Hmm...maybe it's the angle, but I was thinking of sending that the way of wind chime fodder, anyhow...Since it is a mountain bike, it probably is best to use a clean one.

This is the first post that I have personally acquired that is press fit... all others have been SR Laprade, Campy, Sugino, Shimano, Ritchey...

Using great twisting force, all but identical to what the OP has suggested, netted me a badly busted vintage Torpado Luxe. I managed to snap both seat stays free of the seat lug. Never again will I use great force on a vintage bicycle! If a post or stem is stuck, I cut it out, by hand, using a hack saw blade, while wearing gloves. Anyway, I destroyed this poor old Italian Torpado...
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Similar to Randy, I destroyed a frame using force to get a post out. Frames were never designed for such side to side twisting motion. Do so at your own peril.

There were definitely some tense moments...! That's why I had support wood!

The problem with the cut out method is that it was a looooooooonnnnnng post (MTB special). There was no way I could cut toward the bottom, which was basically about 22 cm in...and I've read horror stories where someone angle cuts on long seatposts...and I ain't doing acid...

Glad to see that your post came out without the head of the post twisting loose! I've got a Bob Jackson bike in my basement right now with an early genuine LaPrade post with it's pinned-joint head now too loose to ever use again (or to use for much more twisting attempts). The post has been stuck for some years and I've set that one aside for a while in contemplation of phase two (having thus far used penetrants and dry ice in conjunction with too much twisting of the two-piece post). My next go will involve some serious heat-cycling with another round of the dry ice.
Note that heat-cycling (a torch or heat gun applied to the post, just short of damaging paint or precious transfers) is by far most effective on the more deeply-inserted posts. The aluminum post expands lengthwise, breaking much of the bond. A penetrant added while cooling gets pulled in, and with twisting resumed when the post has cooled or (better yet) been chilled.

I had an absolute worst-case sort of stuck post, three years ago. An oversized(!) steel post pounded down into a Urago frame, probably during the early 1960's.

I couldn't really tell what was going on, other than that it simply would not budge even after much twisting force was applied periodically over several days, while PB Blaster was repeatedly applied to both ends, in conjunction with much thermal cycling using boiling water. This seemed really unlikely in that no stuck steel post had ever challenged me for long.

What eventually got it out was the roughly two tons of pure pulling force in conjunction with beating furiously on the seat tube using a 2# hammer on a piece of Trex material.
Amazingly, no dents or visibly scuffed paint resulted, and no undue stress to the seatstay attachment (other than the hammering vibration and previous twisting efforts).
The bb lug took all of the pulling stress, and held up to it!

I am still recalling the sound of neighbor's windows slamming shut in likely protest of the persistent, alcohol-fueled hammering resonance!
Truth be told, the drinking hadn't been going on for very long, the booze came out only AFTER I noted the first bit of post movement. I took a "celebration" break right there, then "went at it" in the manner of how I cut up a fallen oak limb with an axe just a month prior.

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Wow! That was quite the odyssey!

I feel lazy by comparison!

Thanks for the heads up. It’s time to remove the seat from my old bike !!

haha...not sure I would suggest the fix for everyone! I just didn’t think I could cut that far down with a hacksaw, and refuse to use the acid trick...

the device was a bit more complicated to brace the post, but as I said, I took it apart before I took the picture...

I was also careful to only pull in a perpendicular circle with the frame seat tube.

Misleading thread title! Definitely not foolproof as indicated by the replies from Randyjawa and wrk101. Perform at your own risk...

My first thought. Then I thought of the recent thread https://www.bikeforums.net/classic-v...seatposts.html. Grub screws! Those not so little aluminum eating worms that burrow into seatposts and transform into tiny flies. Yes, it well take all summer and you have to ride the bike a lot to ensure enough exposure to attract the the no-see-em like, near invisible grub flies. (It isn't known how such a big worm can transform into such a tiny fly-like insect.) Grub flies don't bite, They are just after the little slot in the back of your seattube, lay their (usually just one) egg and fly off to seek out another bike.

Seatposts! When all goes well, a delight, (Although they don't really "do" anything. Just keep out butt where it is supposed to be.) When it doesn't, well ....

Ben

Wow! Did I see that right? A 2:1 tackle on a 4:1 tackle? 8:1 final?

I used to race 15' sailboats. I sailed my last one until it was tired enough that I didn't feel good about selling it so I stripped and junked it. I have a box of Harken and the like fittings. A few weeks ago I stretched webbing across my crawl space joists to hold insulation. Needed a block and tackle to get it tight. Found my old boom vang, a wire 2:1 pulled by a rope 4:1. Roller bearing blocks. Got a 1" piece of 1 X 4, screwed the vang to one side, a cam cleat to the other, a steel strap and the other end ot the plank, then just screwed the tang to a stud, tied a rolling hitch to the webbing and pulled. Really easy to get the webbing nice and snug, lying on my back on a stony surface. (Miserable job, but that part was fun!)

Now this block and tackle would not be up to your needed force, I;d have to settle for it pulling the real (and really strong) 2:1. 16: 1 but only about 4" take up. Good thing is that seatposts don't snap back to the original position when you slack off to shorten things up.

I'm keeping that plank, block and tackle, cleat and tang as is. Great little tool. Can't wait to use it again. (Actually I'd better! Could get expensive if I try "just seeing if I can pull my house apart".)

Ben

Here's my 100% success seat post extractor:


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Gotta be REAL careful, wear hand/eye/body protection, mask any paintwork you want to preserve in case of spillover, have some vinegar on hand to neutralize any spills.... but I've done 2 seatposts and one stem this way, and it's a lot less sweat and potential damage to the frame. Dissolves aluminum and leaves steel alone. If you're going to do it, do your homework, this stuff is very dangerous if you get it on your skin...

I twisted a Trek 531 seatube trying to force a seatpost out.

Yeah. I definitely lucked out I am sure. And I hope no one is thinking I thought this was a good idea....

I just thought it an odd contraption...I was hoping it would work but no acid in my world.

And had the stones to post about it, IIRC. That's the one I remember, every time I ask myself if I'm "pushing the envelope" on a stuck post. There's an old '85 Tempo frame with a stuck LaPrade still sitting in my basement, still taunting me, in part because I picture your thread whenever I feel compelled to try turning it just a little harder. Fortunately it's a fairly short post, so it's a good candidate for the jab-saw option.

I could write a book on the stupid things I’ve done, and I’m too old to care who knows about them.

The worst is when you feel movement and think you're going to be in the clear and then realize that the seatpost head has come unbonded to the shaft. Someday I'm going to take that frame to a local framebuilder and have them line-bore the sucker out.

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since yours is shimmed the contact area is relatively small

should not be difficult


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I only achieved 6:1 there, but the rope tension was much higher than "good practices".

And I never had to re-tension, at least not after the post had actually started moving. The rope (all one very long piece, including both blocks, the ratchet wind-up and the bb tethering!) was highly elastic at this stress level, even the trees were flexing.

That sounds like a clever idea using webbing to "wall off" the insulation material. I shopped for a suitable material to do the same thing with my under-floor insulation so that I wouldn't be running my hair through exposed fiberglass! The materials I came up with seemed cost-prohibitive (peg-board/perf-board isn't cheap).

I could see that to much tension on too many webs might start to cause building materials, joists/studs or whatever, to move!