I wanted to find out what if any difference there was between the 3 chainrings I measured. The offset between the SRAM x-sync-2 36T (aluminum) and SRAM x-sync-2 34T (steel) and Praxis eRing (steel) 36T is very close but I did get a difference in offset. I used a digital mic and a Spider Chainring Adapter for my measurements on a glass table. So not exactly perfect but close. So my measurements are SRAM 34T (steel) is the base at 0. The SRAM 36T (aluminum) is -1.2 mm closer to the motor. The Praxis chainring is + .3 mm farther away from the motor. So for people who need to maximize the space between the frame and chainring and you want a 36T chainring you have a reason to stick with steel chainrings.