Cutting out a stuck dropper post- will i die?

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.

Having tried to do the same with a standard alloy post in a steel frame I reckon dying of boredom and frustration are quite likely, even if exploding cartridges don’t get you.

Anyone tried the freezing penetrant spray ?

Like this one….

Crack It Shock Freeze Release Spray- 400ml (WH7-A1)

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.

Have you tried a wide bar through the seat clamp (lower part removed) for maximum twisting torque? Always worked for me.

Could get some gallium and just use it to dissolve the post.

Or caustic soda

Just get the bike over to John The Seatpost Man and have done with it

https://theseatpostman.com/

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?

Possibly 😂

Does nobody simply clamp the seat post in a vice & twist the frame anymore?

Only ever had one stuck post & that shifted it with little effort or drama.

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.

I’ll second the sestpostman.

He really is good, well worth the journey.

@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 🙂

This is clever…

https://www.instagram.com/reel/C7EiowSgZ5c/?igsh=Z2E2dHFibWlpemQ2

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 . . . .