Pulled apart my OEM FC-6500 crankset the other day. There are thin spacers between the spider and the inner chainring. I believe they were put there by Shimano, but these spacers don't show up on any exploded drawing.
I pulled apart another FC-6500 because the inner chainring had been assembled "backwards" - Shimano specs that the side with the lettering face the frame. There were no spacers in this assembly, but I also noticed that the cogs are offset slightly to one side of the ring. By flipping the chainring to the "backward" position, one moves the cogs toward the frame from the spider, just as the spacers do.
Anyone know anything about this?
Are the cogs directional?