Hey all, I’ve got an update. I ended up solving my issue, I didn’t need the split ring, but needed the Fsa supplied crown race labelled h2630a. It didn’t fit any of the other bearings because it is made for the 45 degree 45 degree bearing, which is only included in the FSA ACR no55 Low stack version. The pictures on the internet of that headset have two of the same MR127 36 45 bearings, but with the LS version, there is 1 TH MR127 bearing, and 1 TH MR261A bearing. You need to use the MR127 bearing between fork & frame, and the MR261A bearing on the top, then you use the H2630A part, and then the FSA cover, spacers, (adapter), stem. Now I can finally start the rest of the assembly

did you have any update from them?

As many have already mentioned, the M5 bolt on the seat post clamp is actually too long; it doesn't sit flush with the top tube, causing the dust cap to stick out. I’ve now bought a 30mm M5 bolt, and it fits perfectly. I’m using a Giant dust cap, and it fits perfectly now, too! I can provide feedback on the headset once my handlebar arrives. I’ve ordered the FSA No. 55 LS and a Lightest HBR17 cockpit with an FSA adapter. Still waiting for delivery!

Some people heat shrink the hoses together onto the fork. I don't. I just ran 'em so they don't cross.

The front brake line is connected to my left lever. It runs into the headset on the left side and goes straight down. The rear brake line, connected to the right lever, enters the headset on the right side. Slack is both in the HT (in 3d space, so this includes depth) and going back into the frame. The lines never cross.

With the frame I bought yesterday, the headset parts were included in the total price, though an expander wasn't part of the package. However, I also purchased the FSA No. 55 LS headset along with a Lightcarbon HBR17 handlebar and FSA adapter (€168)—though that part hasn't been delivered yet. I can report back on it later. The headset itself didn't cost me much (€30). Another question: does anyone happen to have a link (perhaps from Amazon) to a rubber plug or cover for the hole near the front derailleur—the one intended for the Di2 cable? I have rubber plugs at home, but they’re too big. I assume the tiny hole under the bottom bracket (facing the road surface) is supposed to stay open so water can drain out? Thanks for your help!

I am repeating myself but the standard seatclamp cover fits great on mine.