Shimano UN-54/55 are not designed to be adjustable in chainline, that's why the have the lip on the left cup. It's not needed at all, but they chose to add it. This is another reason why I do not choose their BB's. Yes, you can add spacers on the right, and I have(no more than 1.5mm) but you'll notice the left cup can't go in any further of course. It's not that big of a deal really, performancewise, as the left side on the cartridge really only needs to be stabilzed, it has nothing to do with the actual bearings spinning.