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I have read about how difficult this can be, and am resigned to just smashing up the old seat post and removing it piece-by-piece. But has anyone on here done that? How hard is the nuclear option? I want to be able to replace the seat post with an aluminium one afterward.
When this happened to me I drilled a hole in the post, put some metal wire through it and poured a boiling kettle of water on the frame so that the aluminium expanded before the carbon. Then pulled for the life of me. It came out!
I used chemicals and force when trying to remove a stuck aluminium seatpost from a carbon frame. I finally used a propane torch to heat it. Might not work for you, since heating the frame with a torch sounds horrible.
Propane torch on the frame has always worked for me.
I’ve done it
I wouldn’t recommend but if needs must! I had a hacksaw Blade to make vertical cuts as deep as I could, then a sharp screwdriver and a hammer to break up the layers and peal them apart. Make sure your ‘screwdriver’ type implement is long enough to get the the bottom of the post. I had real trouble with getting anything to reach the bottom section, hacksaw or screwdriver.
Took me many many hours, I remember being on the verge of tears at 1 in the morning because I had an event I really wanted to do with mates the following day and I thought I’d ****ed it. Ended up getting to bed about 2:30am before my 200k the next day!
It also fills your frame with carbon shards And it’s really hard not to mark the frame at some point with the hacksaw. I ran out of options but, try everything else first is my advice....
The seat post is stuck due to the build-up of aluminium oxide between the carbon and aluminium - spraying ACF30 in there will help break down the oxide and help lubricate the post. Even better is you can remove the BB and get access from both ends. Clamping the post head in a vice and using the frame as a lever may help release it - or you may end up breaking the head off the post off and resort to cutting it out.
as per titusrider. i made a duct tape handle for a hacksaw blade. then spent a whole weekend sawing vertical lines down the inside of the post ( having first chopped off the top ) i used a large screwdriver and mallet to prise the pieces away from the tube. it was deadly slow, the post was very tightly adhered to the aluminium. the bike was a lovely metallic painted trek so i didn't want to use a heat gun.
i found that the inside of the seat tube wasn't linear, it was 27.2 for about 10 or 12 cms, it then widened out, the upshot of this was that the carbon expanded below the 27.2 section making it impossible to pull out without completely sawing it into slivers. like i say, a whole weekend of back and forth. it was eventually very satisfying and caused amazingly little damage to the seat tube.
i think you should also wear a mask, carbon fibre dust isn't particularly healthy for your lungs!
I just had a very stuck reverb removed as detailed here, he certainly works with carbon stuff too:
https://singletrackmag.com/forum/topic/seatpost-man-the-reverb-rises/
Mine was like titusride and harvey
Had to use a screwdriver to lever parts of the post away from the frame
Was quite hard work but not that bad
once most of it is loose you can try torque to free the rest
I've used hot water, I've also cut them out before.
I have a heat gun if you'd rather use that than boiling water. It's a bit easier to control the temperature.
Heat gun. Upside down. In a vice clamped by the seatpost without the saddle clamp. It came out. That was a steel frame though, with a liberal dose of WD40 too.