I've just removed fork from my Marin Four Corners and to my surprise the upper part of headset is not IS with sealed cartridge as advertised, but ZS with loose ball bearing. As the effect I don't know the brand and model.
So I have ZS upper headset with loose ball bearing and I would like to replace with cartridge bearing. As for the specification all I have is what I can measure -- like inner depth of the cup, diameter of the the bearing, its thickness.
How to find a match? Should I look only for bearing, or new cup plus bearing? If the former should I take bearing as thick as cup depth, or the same thickness as the original bearing? And what about the angles (like 45x45 or 36x45), which one I should pick?