New Standert Triebwerk build — headset feels a bit loose, what did I do wrong?

Hey everyone,

over the past few weeks I’ve been building up my very own Standert Triebwerk, and I’m absolutely loving it so far — it rides super smooth! However, after my first proper ride I noticed that the headset feels a little wobbly, not as stiff or solid as I expected.

My main bike is a Canyon Aeroad, which has a really stiff front end, so at first I thought it might just be the difference between a carbon and steel frame. But when I looked closer, I saw that the fork can visibly move inside the headset. If I hold the front brake while standing still and rock the bike back and forth, I can see and feel some play in the fork — enough to not feel fully safe. The bearings themselves are quite snug on the steerer tube, but it seems like they can tilt slightly inside the bearing cups. I tried pressing the top cap down really hard when tightening it, but there’s still a small gap — it just won’t seat fully. Is that normal? Could I be missing a specific step or tool that ensures the fork sits tightly in the headset? I’ve attached some photos in the post. Would love to hear from anyone who’s built up a Standert or had a similar issue — any advice or ideas on what might be wrong would be super appreciated 🙏

PS: Stack height will come down, don’t worry 😅 — I’m still experimenting before cutting the steerer. I’ll also be swapping to Elitewheels with Vittoria Corsa Pro soon, so I’ll share final pics once it’s all dialed in!