any ideas apart from sawing the bloody thing ?

Ive a aluminium frame with a carbon seatpost which is completely stuck. While applying brute force to saddle to help free it up, the saddle is now spinning the top section of seatpost…is this now knackered.

Ive been putting GT85 around the QR for about a week and tried whacking with wooden mallet etc. thanks.

Allyp

To be really honest you need to cut the carbon tube out – Take seat off and just leave the post – Cut a grove inside the tube below the frame and then use a screwdriver and hammer to smash the tube into bits – Also you need to take you bottom bracket out as the bottom end of your frame will be full of carbon bits –

I have had two carbon EC90'S stuck at a cost of over £200 !! 😳 and i have tried everything instead of sawing – no end of people will tell you different ways to do it, but most of them will not work – I even soaked my carbon tube and frame in Coca Cola for a whole 7 days !! – It did not work – Good look….

Caustic soad worked when we got alu and steel parts stuck. Bit of a frame eater though.

sounds like the seatpost is knackered,
in that case,
if you have a big vice then clamp the post in and use the frame as leverage,

have u tried heating the frame up to make it expand? in more sure if it will work…but the thermal expansion of Al is alot higher than that of carbon to my belief…but the plastic resin surrounding the fibre may also expand…poor boiling water down the seat tube and around it maybe? ull need to take the bottom bracket off to let the water out of course.

got the b***ard out at last, lubing it didnt help, the boiling water tratment to expand the frame didnt help. Putting the tube into vice and using bike as leverage didnt work either.

It needed good old fashioned elbow grease to saw the tube down inside the seat tube whilst it was balanced on wheelie bins to avoid dust dropping down into BB. Then it took a good old fashioned twatting with hammer and screwdriver combo to break it up and then pull out with pliers, what a **** job. !!

But at least ive got my beloved bike back.

What caused it to get stuck in there in the first place?

Corrosion between frame and carbon post?

I think the best advise i can offer to prevent this happening in the first place (not much use to you now admittedly) would to move the post regularly and perhaps clean it and put some carbon gripping paste (no idea what the correct name is)on the post so it doesnt corrode in the first place.

thanks for that but yes a bit late ! It was on my hardtail, on which I havent moved the seat since November, unilke the susser where its up and down all the time.
Ive replaced seatpost with alloy this time and plenty of lube !