ec70 carbon post stuck in aluminium frame, WD40 wont do it and now the top has just come off with the saddle still attached, wtf do i do to get this bit of carbon out?

hold bike upside down… seatpost in bench vice….. gently turn frame…. should do it!

ah, I need a bench vice!

good luck to you. as the saddle has come off can you get some penetrating fluid down the seat tube?
i had one stick so badly that i had to cut it out with a hacksaw blade wrapped in a wrag so i could hold it. not fun on a frame worth 1.5k! it worked but it was touch and go, use loads of copperslip now (aluminium seat tube and seat post NOT carbon!)

sure your local car workshop or LBS will help!

Personally I'd leave it in there unless you really need it out. I had the same with a Easton carbon post. It stayed put for 2yrs- still there now with the new owner!

carbon posts…

worth it?

if its snapped you can cut/drill it out mate. worthless now anyways.

How about using a curved file or angular file (like a hacksaw blade but without the pain) and file it out – cut it to the seat post level then file it down the the tube untill you just hit metal – then you should be able to compress it and then soak in GT85 . As its Carbon its easy to file down unlike 7 series alu 😉 Use one of these:

plus gas might help.

or pour boiling water around the seat tube and the seat tube will expand allowing you to be able to remove the seat post.

then you should be able to compress it and then soak in GT85

It's never that easy but there may be no other options.

A vice will crush the post. Leave enough post remaining to grip it afterwards.

Sorry I mean cut it down a bit so you don't have to file as much – Agree with cynical though – leave a bit sticking out – Hopefully uou only need to file a 3-4mm long gap in the post and then you can compress it with some plumbers pliers ?

oh bother, im tempted to leave it in and glue the head and saddle connection back on, what glue etc etc?!?

If all else fails, and you really are at your wits end…… you could burn it out. Blow torch down the tube will burn off the epoxy matrix, leaving a bundle of fibres that will fall out….at the expensive of quite alot of paint on the frame, so very nasty fumes and some unstable carbon fibres.

I have been known to do this in a profressional capacity, in a slightly more controlled way, to unpack impact damaged carbon fibre laminates to track delaminations through the thickness (yes, it's as boring as it sounds 😉

How has it become stuck?

I thought seatpost corrosion was caused by using two dissimilar metals?

I always had the opposite problem with carbon posts in that they wore away with the number of saddle adjustments and eventually became too loose.

Carbon has a low CTE so heating may help.

boiling water didnt work, im just gonna reglue the seat clamp back on top of the post, whats the best glue for alu-carbon bonding? Araldite 2 pk resin??

If the raw carbon fibre is exposed to a nice reactive metal, like aluminium, then you have yourself the makings of a nice low voltage electric cell and it will 'weld' itself together. Best-practise for putting metal inserts into carbon parts is to put a layer of glass fibre between the insert and the carbon fibres as a barrier to stop this happening. That's a lot of faff on a carbon seatpost, in a production environment. The above ins't helped by the act of moving it int he frame which cleans up the alu and exposes the fibres if it sratches sufficiently to go through the surface coats of epoxy/gel coat on the post.

Low CTE – coupled with its low conductivity (of the laminate – the raw carbon is actually a very good conductor) – is a blessing and a curse. With hot water you'll be OK, beyond that you're probably getting towards temps that will damage the matrix. Certainly beyond 200 deg C and you'll start to pyrolyse the matrix, if not actaully cause it to char/burn – which is abviously bad news.

The new joint isn't likely to be too clever – you'll be almost certainly trying to bond over the top of the existing adhesive. Ideally the carbon part should be prep-ed to clean the surface/expose nice, clean fibres to react with the adhesive. The (I assume) metal head would be at least shot-blasted to remove the surface oxide, and better acid etched or use a chemical paint primer. Even after that, the joint probably needs to be jigged to control the bond line thickness…..

In short, it's fubar-ed and you need to get it out one way or another. Soz.