Weight-Weenie Fixed Hillclimb Bike

You might need one or more of the shims which come as part of the hidden 5th bolt package, depending on exactly how thick the chainring is, and you need a conventional chainring bolt to replace the long stepped 5th bolt, but you don't need any thick spacers unless you're using the single ring in the inner position and need to take up the slack where the outer ring used to be.