Solution: go to ST and get educated.
The bike setup was 53/39 with 12-32 in the back. 170mm crank arms might have been the problem, but normally I'm on 172,5mm and I don't know if that would have been enough. Like I said I was a bit worried about the climbing so I wanted a kind cassette. Not cool to work your ass off and then see it all go down the drain on the other side of the mountain.
So what's the solution? 11-25 and/or 55/42?