On a di2 Ultegra, this screw is already at the extreme limit of the plate

Almost built. Just waiting on rotors and tape to arrive.

Build was unproblematic. Internal hose routing through the integrated stem/bars was obviously more of a faff than external routing but not a deal-breaker. Only very minor complaint is the rear caliper mounts aren’t perfectly faced - but not so off to bother rectifying.

Without doubt the hardest and most time consuming job was mounting the Challenge tyres. WTAF. I almost cried, broke my thumbs, cut them up and set fire to them. I’ve mounted many tubeless tyres on many different rims but this was on a whole new scale of ridiculous. Not getting them off in a hurry/ever.

I plan to use it most of the time on road with offroad outings here and there - so wanted something sprightly enough for the former without being so aggressive it’s limited for the latter. I knew I wouldn’t need many if any spacers given how massive the headtube is, and I wasn’t wrong - esp with the positive angle stem / bars.

Paint looks great in the flesh - metallic effect hard to come through in the photos.

7.3kg not including pedals or rotors or bar tape. Pretty good for an XL build that’s not massively weight weenie (wheels are 1530g, tyres 335each etc)

Why not go full Dura-ace front and rear?

Money, I found a random “salvage” DA caliper on eBay, and that was still like $100, which felt like an incredible score at the time.

The other thing is that one of my XG calipers started leaking, which is why I needed to replace it in the first place

Now that I have a setup that’s super light, works well, and is reasonably aero, I can’t be arsed to troll eBay for another deal, and then fork over another $100 for a DA caliper that may or may not work.

Now I glued the little metal plate from Shimano like this.
I don't think it will hold very long time, but the feature of the screw kinda works 

There would be also the possibility to glue (2k) a little metal plate onto the hanger. But I don't know if that is necessary.

Wow!  Good job!  Hope it holds

I don't know about it working perfectly without that stabilizing screw.  The screw keeps the derailleur aligned for more consistent shifting for longer without it rubbing

Now I glued the little metal plate from Shimano like this.
I don't think it will hold very long time, but the feature of the screw kinda works 

There would be also the possibility to glue (2k) a little metal plate onto the hanger. But I don't know if that is necessary.