Re:
25.4mm quill is 1 inch but it fits a 1 1/8" headset.
22.2mm quill is less than 1 inch, but is for 1 inch headset.
28.6mm quill is 1 1/8" but is to fit 1 1/4" headset.
They have to be smaller otherwise they wouldn't fit into the steerer tube.
Sorry if I'm teaching you to suck eggs...
25.4mm quill is 1 inch but it fits a 1 1/8" headset.
22.2mm quill is less than 1 inch, but is for 1 inch headset.
28.6mm quill is 1 1/8" but is to fit 1 1/4" headset.
They have to be smaller otherwise they wouldn't fit into the steerer tube.
Sorry if I'm teaching you to suck eggs...