Are you sure the carbon is broken? and to what extent? I would probably start by removing some of the paint to check if the carbon is damaged. Carbon bikes take quite a lot of abuse before breaking properly, hitting potholes, stone hits etc. Your seatube looks like its broken under the stress of the clamp bolt, and assuming you still have a good 15cm of seatpost in the frame, it might be fine without any repair.

If you still plan to repair it then I would recommend trying reinforce the seatube against the stress the clamp bolt is applying, by creating a ring of fibre around the tube. I.e. dont worry about putting repair material where the crack is.

The way i repair stuff:

• Degrease/clean everything (i.e. seatpost removed)
• Strip back paint to carbon by sanding leaving course grit surface to bond to
• Degrease again
• Block up, mask areas you dont want resin (e.g. seatube inside)
• Apply repair material
• Compact and cure

To compact it, I would keep it simple and use strapping tape.

I would probably just use UD fibre or Biaxial.

I'm after some advice on the best way to repair a cracked carbon bicycle frame.