Originally Posted by
skinny_cyclist
It should be 50mm outer and 44mm inner. So those are the diameters to pay attention to? Not just the steer tube?
There are probably more different standards that you might run into for the internal diameter of the headtube than there are for the external diameter of the steerer tube these days - I know of at least three headtube sizes used with 1 1/8" steerers.