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• #3
And long. Not sure if I remember correctly, but I think it was 400mm from end to end. Presumably it was originally intended for a unicycle!
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• #7
It was cathartic to write. Needed to get that out of my system for a long time :)
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What no video?
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• #9
I wish I'd done a video, but my gf was too terrified to hold the phone and my hands were otherwise engaged. Understandable, given the warnings I gave and subsequent choking when it went critical.
Here's the final thing: https://dl.dropboxusercontent.com/u/2633837/seatpost/langster.jpg Very unexciting and not particularly attractive as it's just a Langster (further uglified by super-thick bar wrap so I don't need gloves and naff but comfy levers). I'll defend my frail ego by saying my weekend bike is nicer.
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No.
But if you're asking because yours is stuck, I'm happy to lend the cutting tool and give practical advice as well as comforting yet motivating words.
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Great read , what happens if you have a stuck seatpost that happens to be hollow?
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Great read , what happens if you have a stuck seatpost that happens to be hollow?
You mean solid? If it's solid, you're boned.
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Just poor the caustic in through the BB junction. It will be fine.
Maybe.
Gave me a chuckle this did. I've got a frame here that needs some caustic. Keep putting it off. Winter project maybe.
Summer's better. Winter slows the reaction too much. Although it's fairly warm right now.
Agreed with BB comment. Some people do it this way. Had I not hacked the end off, that's what I'd have done. Much more likely to damage the paint pouring in the caustic soda however as it won't have a direct path. Presumably can use a hose or a funnel...
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They're all hollow.
If you mean a post having more than one open end, stick a bung of some sort in it. A cork, for example.I used big globs of blu-tack and gaffa tape.
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I feel slightly calmer after reading that. Well done sir.
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About
Death To All Stuck Seatposts! One Man's Saga (PG-13)
Posted by
@part_robot
This is a story of treachery, misery, pain, blood, fear, anger, witchcraft, chemistry and ultimately vindication. It's a story of one man's obsession and desire not to be beaten by a seized seat post
Prologue
In Autumn 2012 I moved to London and needed a bike. Back then I was inexperienced in the dark arts of the bicycle so I went on Gumtree and found myself a 'lovely' red and chrome Langster that was super cheap due to a stuck seat post. But since the previous owner was 5'11 like me I naively thought it'd be just fine. Little did I know... Cut forward a couple of months to Winter and my knees were starting to give me aggro. What I needed to do was adjust the seat post...
Chapter 1: Getting Mechanical
"It's probably just a little rusty", I figured, "just needs a good smack". So I removed the saddle and smacked the top with a hammer. Nothing. Hit it harder. Still nothing. "Ok, so maybe what I needed was a pipe wrentch... I mean, it'd scratch things up but at least it'll be out". But no, a 2 foot pipe wrench did nothing but take chunks out of the post.
"How about some WD40 or some penetrating oil - that solves everything". I filled the seat tube and let it soak over night. In the morning I showed it my pipe wrench but to no avail. It was at this point I went to the forums in hope of answers.
As it happens, I'm a mechanical engineer by training so the advice I read about heating and cooling sounded right up my street. I left the bike overnight in 0C and in the morning poured boiling water over the seat tube to expand the steel a few microns in the hope that'd at least crack the rust. But you can see where this is going; that didn't work either even after several attempts
Fuck.
Chapter 2: Getting brutal
Ok. What next?
By this time it was pretty mangled so I figured I may as well hack the end off of the seat post and maybe cut into lengthwise it to relieve the stress and allow me to pull it out. After all, the issue was caused by aluminium oxide forming, added a few tends of microns to the diameter and then interference-fitting the post to the tube, right? So off went the head
With the top off, I discovered the post was very long indeed. So how on earth would I cut the stress-releaving slots along the length without cutting the seat tube? The answer, clearly, was to make my own slot-cutting tool. So I took a hacksaw blade and cut it into a piece of dowel:
https://dl.dropboxusercontent.com/u/2633837/seatpost/IMG_0677.JPG
When at the perfect 3mm depth (the post wall was 4mm) I turned the blade around and epoxied it into the dowel's slot.
https://dl.dropboxusercontent.com/u/2633837/seatpost/IMG_0697.JPG
Right, seat post, time to die!
https://dl.dropboxusercontent.com/u/2633837/seatpost/IMG_0699.JPG
For four hours I slowly cut 4 long grooves into the inside of the post. Four long, muscle-cramping and joyless hours.
https://dl.dropboxusercontent.com/u/2633837/seatpost/IMG_0700.JPG
When finally the post was left with sub-millimeter slithers connecting the sections it was time to gently pull the 4 quarters away from the seat tube. Or was it? No. Like fuck it was. I bent and pulled and shouted and swore twisted the bastard things until I ripped of the ends. But they were stubbornly stuck fast.
This was depressing. I now had a useless bike that no one would buy and I'd wasted all that time and effort. What followed was a period of sadness and reflection on what an idiot I'd been buying the Langster in the first place
Chapter 3: Science
It was at that lowest point I decided that I didn't give a shit any more. That seat post was going to hell no matter what it took. And I had a suspicion what would kill it for good; caustic soda. You see, aluminium - along with tin and zinc - is amphoteric meaning it reacts with both acid and alkali solutions. Whilst I couldn't use an acid to dissolve out the seat post for fear of damaging the steel, caustic by contrast soda doesn't react with steel. Game on.
Following instructions on various forums I bought myself a 1kg tube of caustic soda crystals and mixed up a strong-ish test solution of about 100g to a litre of cool water. I plopped in a little bit of tin foil and was delighted to see it fizz away. Excellent! Even better an overnight test ate away a good chunk of seat post cutoff. It was time.
I prepared the bike by stripping the frame of all components (including the BB) and sealing all drainage holes with tape. I then cover most of the frame in more tape to protect the paint and slowly poured in the solution. But nothing much happened. The problem was that the outside temperature was so low the reaction was slowed down to practically nothing.
The solution, of course, was a stronger solution. So I mixed up a couple of batches of strong stuff and poured it down. This time it was proper powerful and vapour and foam erupted like Vesuvius. "Die you bastard!!" However, at this point I noticed the frame starting to steam. The reaction was so violent and exothermic that the frame was already beyond the boiling point of water. But whilst I did need to keep a hose on it to call it down, this also meant that the reaction itself could keep up the required temperature throughout the cold nights and hopefully sustain the attack.
https://dl.dropboxusercontent.com/u/2633837/seatpost/IMG_0737.JPG
Chapter 4: Redemption
After a day, I checked and was disappointed to see things weren't progressing all that fast. It'd eaten away a good half a millimetre but hardly more. I repeated the process a couple of times over the next few days but I was running out of caustic soda. Worse still, the forecast showed sub-zero temperatures and I knew the reaction would slow to nothing then. So I made an important decision; I decided to mix all the remaining caustic soda with relatively small amount of boiling water.
It's worth mentioning at this point that the act of dissolving NaOH in water is itself exothermic and so hot water + hotter = trouble. Do not do this. It's a terrible idea. It can blind you and scar you for life. It's very dangerous and not in a Jackass-style funny way. I was stupid. But I was obsessed and so here I was with a steaming jug of boiling saturated caustic soda solution. Time to fuck shit up.
With one hand on the jug and the other on the hose I poured the solution down the seat tube a few centilitres as a time. The reaction was beyond crazy, spewing boiling super-heated black shit all over the place. "Mwhahahaha!!! FUCK YOooOOU!!!" In a matter of minutes first one and then another slither of seat post rose to the top. After 30mins, I was pretty sure nothing was left as the reaction had subdued. I hose out the bike and looked down the hole. "Pretty clear, nice". But when I poked a stick down there I felt resistance. Some had remained!!
This was depressing. I only had a few centilitres of solution left and I'd used my last chance before winter. Hopelessly, I poked a coat hanger down the hole just in case something would move. And it did! Slowly, I used the coat hanger to draw out what looked like a razor clam covered in thick black oil. "YYEEAAASS!!!" After one more poke around I hooked the last piece out.
https://dl.dropboxusercontent.com/u/2633837/seatpost/IMG_0779.JPG
"Outstanding!!!" Words cannot describe the relief and the shear beauty of that success. It was over. Finally I could move on with my life.
Epilogue
If I've learnt anything, dear reader, it's that you should never buy a bicycle with a stuck seat post unless it's worth a lot of money. And if that's the case, and the post doesn't budge with a few smacks of a hammer, get some caustic soda and buckle yourself in for a ride. Finally, do make sure you regularly check and grease your seat posts because stuck ones are an absolute ball ache.
I hope this helps someone. And if anyone else near to Deptford in SE8 wants to borrow my slotting tool, I'll gladly lend it out.
https://dl.dropboxusercontent.com/u/2633837/seatpost/IMG_0765.JPG