This is a custom length aluminum MicroSpline spacer. No need to stack multiple sizes of spacers on top of one another, as this could replace those stacks with 2 slick pieces. Our cogs are 8.4mm wide, so the total length of both spacers and the cog should be slightly more than the length of the hub body to allow for adequate preloading. Each spacer could be different lengths, allowing you to position your cog wherever you'd like on the hub to dial your chain line down to a tenth of a millimeter!
(Note that the narrow and wide are the same thing; the shopping cart can only handle 100 variants, and this is a simple way to allow ordering a wider range)
If using our lockring, use this method to determine spacer widths:
1. Measure the spline body that the spacers will bottom on. My MicroSpline freehub measures 26.2mm from bottom flange to tallest point.
2. Our cogs are 8.4mm wide, so 26.2mm-8.4mm is 17.8mm for the pair of spacers. For a centered chainline, simply divide by 2. It's 17.8mm/2 = 8.9mm per spacer in this case.
Our lockring needs an extra 3.0mm spacing from the freehub because the threads won't go completely to the square shoulder due to tool width and lathe deceleration distance. This means the outer spacer gets 3mm added to its width. In this case it would be 8.9mm+ 3.0mm = 11.9mm.
3. If you want your ideal chainline to vary from center of the freehub, you simply add that distance to one and subtract from the other. If you wanted to be 2mm more inboard in this example, the inner spacer would then be 6.9mm and the outer one 13.9mm.
Torque spec should be 40Nm.