Thanks for the tips and the link to the topic!

I've already ordered a longer expansion plug, maybe that helps.
And I think i'm going to modify a normal round spacer and try to fasten it with the normal round topcap that was provided by velobuild. Because I also think the play is caused by the original flexible top cap that deforms when I torque it.

Will post an update if the problem is solved!

Hello everyone,

This is my first post on this forum, after many hours of reading.
I'm currently the owner of a grey-white-red GF-002 in size L.
It is setup with the Sram Rival AXS group set including powermeter.
I also used my AR56 lightbicycle wheelset with the grey Vittora tires.

Before I also had a GF-002 in matte black with a mechanical Sram Apex1 group set which I sold a couple of months ago.

I love the bikes, but on both I had/have some problems with the headset.
On the first matte black one I've used the integrated aero bar that was delivered with the old C-ring.
After filing the knobs of the C-ring and the spacers I eventually got rid of the headset play, and it stayed away.

But now on my new grey-white-red one I placed the separate stem with an FSA ACR compact bar.
So that I have the opportunity to place aerobars.

This bike already came with the newer C-ring without knobs but I can't get rid of the headset play.
Every time when I tighten it again then after some rough roads the play is coming back.
When I tighten the topcap I will get the play out and then I tighten the bolts of the stem to 5.5 Nm.
I also used Carbon paste.
But when riding over a rougher sections of road every time the play comes back.

Any ideas?
Greetings from The Netherlands