It's all lies!

[dfthe1]

Thanks all.

I tried all the "wanging it about" tricks -- pipe wrench, bench vice etc, but to no avail. And I did leave an inch of seat post visible before doing the hacksawing, but when it came to the collapsing the post in on itself bit, the visible bits broke off. Which is why I find myself where I am. Pretty sure there is some kind of chemical bond, as chiselling pieces away from the tube is hard work!

It's quite possible the saw cuts didn't go all the way through, but it's very hard to tell -- I was through at the top end and risked starting cutting the steel.

I guess I'll just persevere with what I'm doing. It's working but very slowly. Is ammonia paint-safe?

It's all a learning experience -- I'll remember to check the seatpost next time I buy an eBay bike. I suspect, like a lot of things on the bike, the post hasn't been touched for 20+ years!

 

[Yellow Saddle]

And now it is all downhill from there.

 

[Cycleops]

As you've found out if the seat post is non movable it effectively turns the bike into junk. That's the trouble if you buy an old bike without inspecting it as you might do on eBay. Always inspect before buying or at least get an assurance its free. Here endeth the lesson.
Sorry.

Edit: Your best bet would be to get it machined out on a lathe as someone else suggested. Find a local machine shop under 'engineering services'. Shouldnt cost too much.

 

[Wobblers]

Lacking access to a machine shop probably your best chance at this point is to dissolve it. Caustic soda/lye/drain cleaner (they're all the same chemical: sodium hydroxide) will certainly work. A less aggressive chemical is washing soda (sodium carbonate) which is much milder, won't attack steel and still remove the aluminium. It shouldn't be hard on the paintwork, either. Expect it to take some time: hours to days.

 

[biggs682]

@dfthe1 I have a rather nifty drill piece you can borrow if it's a 27.2 post only used once with 100% success .

 

[dfthe1]

@dfthe1 I have a rather nifty drill piece you can borrow if it's a 27.2 post only used once with 100% success .

Really? Are you anywhere near Warwickshire?

 

[Ajax Bay]

Are you anywhere near Warwickshire?

Presumably
https://www.google.co.uk/maps/place...xd69e65e7704b1d28!8m2!3d52.302419!4d-0.693964

 

[biggs682]

Really? Are you anywhere near Warwickshire?

Northamptonshire

 

[Lozz360]

Yes. I wasn't sure if the inside of the can was coated. I had added an edit about research whilst you were posting.
The only reason it came to mind was I happened to see a video a while back about someone removing a stuck bolt from an engine block, something I am struggling with at the moment.
Actually thinking a little more about it, it may have been a steel bolt in an aluminium engine block, which is the reverse of the OP's current predicament. My bad. Apologies

Aluminium beverage cans are coated with lacquer on the inside.

 

[Old jon]

[QUOTE 4782172, member: 9609"]are you sure you hacksawed through 100% of the ally post ? just a little bit still connecting them will keep them well and truly jammed in.



does coke not come in an ally can ?[/QUOTE]

An internally varnished ally can
Ooops, beaten to it

 

[Drago]

...and that's why one should not insert long seatposts all the way down like that in the first place. Cut them down if necessary.

I fit 400mm posts to all my bikes to spread the load because I'm a big fa..., er, very muscular fellow, and I've seen similarly chiselled fellows lever frames apart where the crossbar meets seat tube. However, I regularly remove the posts for inspection and keep a fine film of grease. I know that can create its own issues, but regular inspection and cleaning is a lot less stressful than a broken frame.

 

[Yellow Saddle]

I fit 400mm posts to all my bikes to spread the load because I'm a big fa..., er, very muscular fellow, and I've seen similarly chiselled fellows lever frames apart where the crossbar meets seat tube. However, I regularly remove the posts for inspection and keep a fine film of grease. I know that can create its own issues, but regular inspection and cleaning is a lot less stressful than a broken frame.

If 300mm of that 400mm is inside, it is completely excessive.

 

[Drago]

Excessive for a 19 stone man who's had friends of similar size break frames at that join? I'd rather 50cm too much than 1mm too little. Its not problem, the weight is negligible, no one sees it, I keep it clean and free, so why not?

 

[dfthe1]

I spent an hour in the garage and made another 3/4" or so progress (that's three quarters -- not three or four!)

I'm the only one who's going to ride the bike. The discussion above got me thinking about minimum post depths. I don't actually need to get rid of the stuck post all the way down -- just enough to allow me to safely put another post in, and I can cut that down to my size.

So is there a standard minimum post depth, and does it vary by post type and saddle height?

 

[S-Express]

So is there a standard minimum post depth, and does it vary by post type and saddle height?

Typically, the post just needs to extend below the seat post/top tube junction..