I'm assuming you are referring to an older style headset nut. It can be tightened and loosened but too tight and the bearings will get wrecked quick and too loose and there is dangerous play in the entire front end. Either way, it seems unlikely that on-the-road adjustments for the purpose of refining the handling are unlikely in a race situation where the mechanics would be out of work quick if the headsets on the bikes they work on needed any adjustment at all.
But what do I really know?
Last edited by 55/Rad; 06-01-08 at 10:37 PM.