Currently I have a spacer between the outboard side of the crank spider and the chainring in order to give myself clearance between the chainring/chainstay. When I had the rear cog flange out, the belt was tracking in and I was considering adding a spacer to the bottom bracket to further bring the chainring outboard. I had forgotten that I now need to bring the crank inboard because I've flipped the cog flange in (as recommended by Gates) and have the belt tracking out. Still, if its safe, a spacer on the BB might be a better option for chainstay clearance than a spacer on the chainring bolts.