help please

[sisyphus]

The cola didnt work because you forgot the ice and lemon!

I recently shifted a seat post from an old carlton by turning it upside down and locking the seat post in a vice - simultaneously blasting it with heat - turning the frame at the same time.....I nearly set the shed on fire but its going to Argos for a respray soon and will be like a new bike no doubt.

 

[Tel]

Alloy expands faster than steel with heat. I'm no scientist but I think that by using the heat method (which certainly works) the expansion of the two metals, despite which expands more first, breaks the chemical bond and alloys penetrating fluids in, I'd recommend Plusgas.

 

[eg2]

I'm used to cars so this idea may be a bit extreme for a bike...

weld an old socket onto the top of the seatpost, clamp the frame and then use a torque wrench on the socket. once the post is moving you should be able to remove it quite easily... :/

 

[keithglos]

You obviously need something clamped on the top to get some leverage.
Even an old frame with the same size tubing.

 

[Simon Daw]

The ideas above are all valid, but I'd just add that stripping the bike completely and clamping the seatpost into a vice, then turning the frame, gives a lot more leverage. Don't pull on the chain / seat stays by themselves, or you may end up with 60mm / 220mm rear hub spacing and a bike that rides like a crab.

Obviously, this assumes that there's something "clampable" on the seatpost. There often is, but even if not that seatpost is probably a goner anyway; consider creating flats by cutting. The trouble with using the saddle as a lever is that it absorbs quite a bit of force.

As a very last resort I have sometimes had to cut the seatpost off a little above the seat lug and then cut (carefully!) through the post, out towards the frame. You can generally tell when you've hit steel! If you've left enough it's sometimes then possible to get things moving by squashing the post and breaking the chemical bond that's holding it in place. If not, keep on cutting until you can hammer and prise the slices out...horrid job, but you'll get there in the end. Last resort, though.

 

[cobby1970]

Finally out, tried the heat method with plenty of plusgas...no joy
tried coca cola...no joy tried swearing...no joy ended up drilling an hole straight through the post and putting a long length of bar through to twist it out .....JOY brute force wins the day