Just got a 2016 BH Aero RC and my LBS is telling me that the standard rear Ultegra brake caliper (BR-R8000) won't work on this frame. According to them, the only thing that will work is using a front brake caliper with a spacer. I tried emailing BH but they're not responding.

Does anyone know if this frame works with another Ultegra brake caliper like a 6800?