3. The top headset bearing is recessed too far into the head tube cup, causing the headset cover to rub on the frame, preventing the complete headset stack to properly compress. If this is the case you will need a thicker headset bearing (7mm, 7.5mm or 8mm thick) or a thicker c-ring so that it sits flush with the top of the headset opening on the frame, thus preventing the headset cover from rubbing the frame. EDIT: Another resolution is adding some micro spacers between the c-ring and top cap.
This was an aha-moment (thank you for that!) for me and I ordered two bearings (7,5 and 8mm) right away today. I am having high hopes that this will might solve my problems (Velobuild VB-R-099).
Just a remark on the other resolution with the microspacers: shouldn't the microspacers be added between the c-ring and the headset/bearing cover (and not the top cap)?
I did try to use microspacers, but in my case, my compression ring is U-shaped and I did not find any U-shaped microspacers, so I ordered regular round microspacers which I cut so they would fit the U-shaped compression ring. I was not satisfied with the result however. The idea that the microspacers could shift and touch/damage my brake hose in the steering tube made me abandon this option.
