Hi guys,
I have finished my (first ever) built and ran into the same headset problem, its already more than tight and there is still play left. I dont fully get why and how you guys fixed it, so I would immensely appreciated your feedback. I also had to move the settings of the derallieur almost as much "inwards" as possible for the derallieur to sit over the cassette properly and was worried but shifting is smooth so I dont see any reason to change it.
Here is my built:
Grx Di2 827 (fully wireless) with 105 brakes and levers, enough for me and I much prefer the "slimmer" handles.
Elitewheels whatever

Velobuild Gravel handlebar
44t chainring, I will need bigger. Might even try a 9-45 cassette if 46 is the max chainring.
I would be very grateful for you input. Attached you see the expander, the cover and how the expander sits on top of the fork.
How on earth can I get rid of that headset play?
Shim? If yes, where is that supposed to go?
Shorten the fork another mm? -> From how it looks, that shouldnt make a difference. The cap sits correctly and I can properly "pull" the expander towards the top cap.
It feels more like there is "back and forth play" so when I pull the front break and push / pull the bike, the whole cockpit and spacer tower moves back and fort about 1-2mm.
Is that what you guys are describing?
Its driving me nuts and I am really at a loss at this point.
@Niculasch: LOVE your built, looks sick! Great colour, very nicely done.
Which handlebar have you got? It seems you can easily use a different expander, because the round top cap from the Deda fits?
I got the gravel handlebar from velobuild with the custom top cap, that wouldnt work / look stupid.
Also, is the chainline ok? The p515 is a narrower crankset than GRX / SRAM xplr, right? I initially wanted to built it with a p515 as well, have one in stock, but stepped away after reading about chainline.
@Motus: That looks like the same handlebar I got. Did you have play in the headset and how did you fix it?