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I have a very stuck dropper post- aluminium in a steel frame. After having soaked it in penetrating oil, used a car jack, used a mallet I cannot get it to budge at all.
So I've written off the post and am thinking i will cut it out. My main concern is how much pressure is there in the system?? If I drill a hole in is that a bad idea? The post can be extended to the top so I guess that's low pressure? Unfortunately the nut at the top is spinning freely, so I can't remove this to let pressure out.
Look up stuck dropper post on Instagram and find someone with the jacking rig that goes through the BB. Ignore shite about ruining frames, Stirling Bike Doctor did loads before he moved on.
Stirling Bike Doctor’s post pulling contraption is now with Iain McKenna who runs The Bike Works in Stirling.
Kind of hoping to DIY ready for the weekend... I guess I'm wondering how bad it is to cut into the under pressure but so I can cut the whole thing out
The chances of success are minimal
Where are you?
How are you proposing to cut out
I didn't die but my On One C456 did....
I had same problem last year. Borrowed this contraption off a friend as he had the same problem year before.
Yes that is exactly what is called for! Local bike shop didn't seem keen to take it on.
I was going to do as in the Sheldon Harris website, cut down the tube vertically then fold it in on it self. Hopefully 'breaking the seal', or at least giving a proper place for oil to act on. But the cartridge is in the way to stop me properly going at it.
Actually wonder if a jigsaw will do it nicely without damaging the cartridge
Anywhere near Sheffield? I have the struggling stirling bike doc machine here
I love these threads. Reminds me to suddenly jump up, run to the bike to release the post, drag it up as far as i can and apply a liberal coating of anti-seize.
Thats me done and happy until the next 'stuck post' thread 😀
How yours comes out ok 🙂
@bikerevivesheffield, in the south west! It's going slowly. I think the technical term is a massive ballache
@flyingpotatoes - that's some great bodgery/bush mechanic's. 👍
Tried plumbers freeze spray?
Having cut a standard aluminium seatpost out of a steel bmx frame I can confirm this will be a massive ballsache and you have to be so so careful not to mark / cut the seat tube itself. I’d cut vertical slots in the post hoping I could then bend it inwards and wiggle it out. Didn’t work - had to cut down the post inside the frame too. Tried doing it manually but it was slow / not very effective so ended up using a reciprocating saw which was much more effective. I got there in the end but throw was an old steel Haro bmw frame that didn’t owe me much. I don’t think I’d take it on with a nice frame I actually liked.
Anyone tried the freezing penetrant spray ?
Like this one....
https://rodtech.uk/product/arctic-crack-it-400ml/
Other versions available widely at places like Screwfix, car bits shops etc.
I used some a few weeks ago on something on the car, and was very surprised how well it worked. Barsteward-tight bolts not budging with a big breaker bar, loosened easily 10 mins after using this stuff.
I've not used it on a post. But worth ag go for under £10 if not already tried ?
RM Cycleworks in Carlisle has a stuck seat post remover thingy.
Could get some gallium and just use it to dissolve the post.
Or caustic soda
If it's an aluminium post in a steel frame, I wonder could you use gallium to corrode the aluminium? You would need to keep the frame warm at around 30° c for the gallium to remain liquid, but you could do that relatively easily either in the sun or by using a hair dryer or heat gun. The gallium within a few hours would migrate throughout the entirety of the aluminium of the post and would corrode it to the point where you could just crumble it out with your fingers.
I've never done this on a bike before but the gallium won't harm the steel at all,And it will completely destroy aluminium parts
Having dissolved an aluminium post in a steel frame once I wouldn't even bother starting any other method now. It's that easy.
Key is patience, find a way to seal the post upside down, pour the mix in via the bottom bracket and leave it at the bottom of the garden. Change the mix every night and after a few days the post will pour out as a grey soup. Zero physical effort and costs about £4.
The caustic soda didn't leave a single mark on the paint on the frame when I did it but no idea if that's always the case.
Can we assume OP has succumbed to injuries caused by DIY misadventure yet?
You are lucky if that's worked, so many I see seized solid
Not dead! But hot and bothered and unsuccessful! Latest try is half a can of freeze spray inside the post and around it which hasn't worked so far.
Will leave it and try the rest of the can later. Failing that I guess caustic soda is next
I have used hot and cold treatment on stuck seatposts, but not dropper ones.
Hot almost booking water and then cold water . Repeated many times and broke it the bond eventually.
Good luck.
@bikerevivesheffield do you think your machine would pull a seized dropper out of a Ti frame?
If so, I'm only down in Nottingham, so may take a trip up 🙂
Thanks for all the suggestions @honourablegeorge that came the closest and twisted it a little, but has now basically all split above the frame, so a vice isn't gripping it it's just deforming.
So basically left with caustic soda. Just wanted to see if anyone has done it with a dropper posts?
The bit I'm worried about is the sealed cartridge and the pressure it's under. It's a brand x ascend. I can't find a materials list online for what the cartridge is made of, but if it's also made of aluminium I'm worried there would be an explosion of caustic soda!
Also if any reads this in the future, I wish I hadn't cut it! I think the freeze spray inside onto the aluminium and using a stem and handlebar for leverage would have done it
Oh, I'd absolutely drill a hole in the cartridge before sticking caustic down it, even smashing a hole with a f off big nail.
Oh, I’d absolutely drill a hole in the cartridge before sticking caustic down it, even smashing a hole with a f off big nail
So is that actually safe? It's sealed and somewhere around 300psi?
I'd quite like to shoot it with an air rifle!
Wow what a **** up
If anyone reads this in the future.. caustic soda doesn't necessarily work on dropper posts, it seems the lower part is steel, so the aluminium section has dissolved and it's been left with a stuck section of steel right down the bottom! So the only thing left is to drill it out.
Overall, massive ballache
Would be very surprised if the lower were steel . . . .
If anyone reads this in the future, ignore all the ****ing about, save yourself the hassle and just find someone with a post puller to do it for you.
OP you've really buggered up now, how are you going to drill it? Seriously, send it to someone professional, you're at the point where you stand a good chance of doing irreparable damage.
Hard to think how much worse this could be going, but at least you've only flared the seattube slot a little.
Is there not enough now to grip, mole grips around some rags, whilst you try freeze spray again?
And I'd still be soaking that all day every day to help penetrate it what you can.
£80 quid for the seatpost man (who would have saved the post probably) would have been a lot less stress but I do feel sorry for you op as these messages reminding you of that doesn't help much and I can imagine you must be pretty fed up with it
No chance the lower is steel. Has the caustic soda really not touched it?
I do feel sorry for you op as these messages reminding you of that doesn’t help much and I can imagine you must be pretty fed up with it
I was making the point that at this stage you're going to need a bloody long drill, a bloody long chisel and a very steady hand to even stand a chance of drilling it out and freeing the remnants. The only alternative is to get a bloody long drill, a bloody long tap, some threaded bar and a slide hammer and hope that shifts it. I'm not confident it will, it needs jacked out but how you do that without damaging the seat tube throat is beyond me. Then it will need reamed regardless.
Seatpost man can probably still get it out, the puller could easily do what I'm describing without damaging the frame. There is no sunk cost fallacy here, besides the already totalled seatpost.
Might sound counter intuitive but a good smack downwards might loosen things a bit. Maybe clamp some mole grips around whats left to stop it going to far in.
The frame is looking distinctly haggard round the slot now, I think you're in frame repairer territory....
Just wallop it further down and forget about it, new external hose dropper for you :good:
broken the forum too now can't upload the photo
So for visualisation purposes this bottom bit is now 8 inches or so in. So it's rideable now with a a standard seat post going in much past it's minimum depth. I really don't think the frame has taken real damage, it's a steel frame and the seat lug is only slightly flared a the top
Yes obviously in hindsight the seat post man was the better idea, less helpful there not being a similar set up anywhere near.
Can't work out how to quote someone but @squirrelking it wasn't a dig at you or anyone, just genuinely feel sorry for the op
Caustic soda would still work I'm sure. I've done 4 or 5 that way. I'd not leave it in there it would drive me nuts
Adjustable reamer? - you'd need to be able to measure the remaining elements of the seatpost to figure if it would work or not
Can't get the eBay link to work. Search for
"Expanding Adjustable Hand Reamer HSS Cutting Tool 6-84mm All Size Metric Reaming"
However - £40
Any updates mate? If you want to sell me the stooge cheap I love a project ?
Come on chap, we are dying to find out the progress