Shimano chainsets - rings

lef Posts: 728
edited August 2011 in Workshop
Does anyone know whether the rings that are described in the tech docs as Y-1F3 16000 are always required? These are the rings that sit between the cranks and the BB cups.

I was just checking something up on their techdocs as overhauling the BB and noticed these were shown in the exploded diagram. However I have a couple of bikes with ultegra 6700 and a bike with 7900 and none came with these rings on.