On a different note: Turns out my criticism towards the shifting performance of my er9 was unjustified. At first I thought the ZTTO monobloc cassette was to blame. But the groupset behaved the same way on the turbo with a different cassette. But it appears that the chain was to blame. As I wrote in a different thread: I gave the ZTTO chain a try because I was impressed by the quality of their other stuff. I bought the gold chain with hollow links and pins for somewhere around 25EUR. Super cheap and super light, Turns out this chain has all the style but zero substance. It's worn after only 4000k - and that's with hot waxing. I've never worn through any chain that fast.
So I took it off and decided to put on a Campy Super Record 12sp chain, because it was heavily discounted. I got a Chorus chain on my other bike which works very smoothly and it shows barely any sign of wear after 6-7000km. WHAT A DIFFERENCE: Before, I could never set the RD up perfectly. There would always be the occasional crunchy shift. The shifting now is smoother and a lot quieter without touching anything. Just by switching out the chain. I might have to fine tune one or two gears. But it's a night and day difference, especially when shifting into a harder gear. The chain just drops effortlessly onto the next smaller cog.
I'm now actually a lot more impressed by this groupset than I was initially. This feels very nice indeed.
And I'll definitely steer clear from ZTTO chains for the time being.