The smaller the rolling element (the balls) the more sensitive to preload the headset will be. To fit bearing cartridges inside a headtube and outside of large diameter steerers the parts need to be small. Also the angle of contact the balls have between the races come into play.


Long story short, yes, some headset designs have very little range of best preload. And the best preload is nearly none. Start the adjusting process with the headset a tad loose then tiny bit by tiny bit loosen the sten pinch bolts and snug up (remember tiny bit) top cap and retighten the pinch bolts. Test the adjustment having slop by applying the front brake and rocking the bike fore and aft. You should be able to feel the slop if the adjustment is loose, placing a finger at the gap between the fixed (head tube) and the moving (steerer mounted parts) helps to feel this slop. When the headset is properly adjusted the slop will just have disappeared. the problem with trusting the swing of the fork is that there is a lot of leverage the wheel and bars have over the bearings. The fork can feel easy to swing yet the bearings can be too tightly set. Headset adjusts are harder to get best then many (who haven't done one) think they should be. Andy.