Bought a new un55 for my old mtb.
73mm shell but there is a gap 5mm at least between the bearing and the cup on the nds.
Removed it and checked the width, 73mm from edge to edge, but there is a lip in the nds cup that stops the bb shell, leaving that gap.
It seems as though it’s a 68mm shell with a special nds cup to space it out.
Is this a thing? Am I going mad?