Originally Posted by apclassic9
So, just to recap - what I'm getting from all this is that grinding down the top or bottom of the head tube will not change the geometry? There's not too much available to reduce off the bottom (@ 2 mm before you'd hit the weld).
Here is the correct information:
1) DO NOT "grind" the headtube. Get the bike shop to use their facing tool to mill it down.
2) Removing material from the top of the headtube will make the headtube shorter
3) Removing material from the bottom of the headtube will steepen the effective head angle and make the headtube shorter.