Swollen Seatpost?

Just been giving my Plug a bit of long overdue maintenance and found the seatpost to be jammed in solid.

There's a slight bulge on the seat tube that I've never noticed before, almost as if the seatpost diameter is too big.

It's the stock alloy post in a steel frame, has anyone ever had anything similar?

Is it best to just leave it in there or am I about to cause myself a whole load of hassle trying to get it out?

Ive bent my seatpost and its also jammed in. Any suggestions for unjamming it also welcome!

cheers, Cris

**Sheldon Brown to the forum please, spillage in aisle C**

Cheers pants, already seen that.

I was more wondering why a stock post which fitted perfectly would appear to have swollen and done that to the seat tube. Sounds mad I know, but can this happen?

Or is it more likely bent? (although there's only about 100mm showing)

😕

(mostly put it up in response to kitecris)

I don't see why a bent post should stick – assuming the bend is above the clamp

Is it possible there's not much post in there and you HAVE bent the post inside the tube ? (doesn't sound that way from your 100mm showing)

I can't believe that swelling is just internal corrosion or whatever the electrolytic equivalent might be (I think steel & alu supposedly can interact can't they?)

… but then I'm more of an idle speculator than a facts kind of bloke

Alloy seatpost in a steel frame can catalytically corrode – and the corrosion takes up more volume than the alloy it replaces. I find it hard to believe this can be enough to bulge a steel tube however but I am not metalurgist

You got any pics this sounds bizarre.

Just replied to a similar post by Mucker, check my profile for advice on removing.

I'll try and sort some pics later, although I don't think they'll show much – it's not a lot to look at, but you can feel it when you run your fingers over it! 😯

I'm not desperate to remove it, but can't say I'm happy with it being like that.

More concerned about the consequences if I do need to change it.

Here you go, it's about as good as I can get…

Or try here if the image doesn't show[/url]

I suspect the 'bulge' is actually butting on the seat tube that you just never noticed before – i.e. totally normal.

If the seat post is stuck then that's a separate problem. Could be real corrosion, or it could be that you bent it a little then put it down too vigorously and jammed it. Try clamping/wedging the saddle in something and twisting the whole frame to slowly twist it out.

Agree with b17 – likely just an externally butted seat tube. Normal process for removing stuck seatpost required.

Cheers b17/sam, hopefully picking up a vice later so I'll give it a go.

I'd be really surprised if it's bent and been rammed back in despite me being a heavy handed idiot! It's never had any more than 100mm showing and has only been removed/adjusted once since I've had the bike.

Which probably suggests corrosion as I originally thought.

Anyone here with a Plug that can confirm whether or not the frame is butted in this area? (I didn't think there was any on these – plain gauge all over)

If it is corroded in and you decide you do want to try removing it then you need to crack the corrosion. It you've tried the usual screwdriver/twisting the saddle without success then you can try this…

Remove the wheels and mark the seatpost with a (washable) pen just where it enters the frame. Place the bb on a piece of scrap wood. Hold the frame upright and cover the top of the seatpost with another piece of wood then hit it with a hammer – as Sheldon Brown says – you shouldn't install a seatpost with a hammer, but here you're just trying to crack the corrosion. At the first sign of movement, stop, and try pulling it out again…

If done carefully you won't damage the frame/post and its easier than the blow-torch/hacksaw method.

I removed a stuck post by carefully tapping a tread on the inside of the post (the head of the post came off during previous attempts) then used a slide hammer with an apropratly sized bolt welded on the end. Worked a treat. The post looked like it had been stuck on some roughness at the bottom of the seat tube.

double post, soz!

Thought I'd update this for anybody that may have been interested or struggling…

The post had corroded badly and pushed the seat tube diameter out by 1mm. Not happy with it staying in there so over a few weeks I soaked it in lots and lots of plusgas, from above and eventually from the bottom (when I knew I wouldn't be needing the bike and I could be arsed to take the BB out)

Drilled through it and used a rod to twist it out. Wouldn't budge.

Stilsons and more Plusgas. Still nothing.

Repeated the above with the help of a heatgun. Didn't wanna know.

Cut the top off and tried sawing/chiseling it out. Just stayed in there, welded to the seat tube.

Finally, turned it upside down and bunged up the bottom. Poured acid (tested on a sample piece off the tube first) in through the hole in the BB shell. Left standing in a bucket, smoking away for a few hours and…result! 🙂

Hope you flushed and flushed again after the acid trip?

Yeah, pretty thorough…I'll update again if the seat tube collapses on me!

Gotta love the acid 🙂