TRP spyre mounts wider than rear disc mount positions

Question

I recently picked up a Cannondale CAAD12 Disc and some TRP spyre disc calipers for it. Just lining up the mount holes on the spyres to the mount positions, the front disc mounts on the fork line up great. Hoever, the mount positions on the rear are closer together than the mount positions on the spyre caliper. The two spyre calipers are the same, but the disc mount positions on the rear of the CAAD12 frame are closer together.

Is there an adapter or something I need to get? Or a completely new caliper? Will this affect what size rotors I can run?

Answer 1

That bike has rear flat mount. If there's room for a post mount caliper plus adapter, which from looking at some pictures I doubt there is, the rear post mount adapter of the right size is your part, something like:

If there's no room then you need a flat mount caliper instead.