I didn’t know it was a thing either. It just looked like it would fit correctly if I swapped the mount around so I tried it.AOK mentioned that he flipped the caliper mount around and it positioned the caliper properly for a 160. I didn't know that was a thing you could do
Having a 180-specific rear mount seems like an odd choice for this frame. Heck my Ripmo doesn’t have a 180-specific mount.