1" ID roller bearings are pre-installed and the brake rotor/pulley flanges come in H-D style mount pattern with 56mm center

and up to 2006 XL models

when combined with shorter than stock rear shocks

81-83 650 GSG

XTM® multi-position protector-ready system Integrated pockets for shoulder

arlen ness velocity 90deg air cleaner for harley BS90 1" ID roller bearings areIt greatly helps, when trying to maximize airflow through a filter, to have a large filtering area. But building a huge filter was a no go, it had to be small and very effective. This is where the Arlen Ness design artists started. Adding the inside surface of the air cleaner to the outside adds a huge amount of filtering area. With the integrated radiused air inlet this air cleaner showed some of the highest flow numbers that Ness ever tested. The