Mounting caliper brakes without center hole I recently purchased a used Bianchi Cross Concept. I'm trying to upgrade the entire groupset.
When coming to the rear brakes, I realized the bike frame has two holes (1 on each side) for mounting v-brakes. However, the new rear brakes are I got are caliper brakes which need to be mounted to a single hole in the center (see picture). It's a carbon frame so I can't drill anything.
I'm wondering if there are any methods to make this work, some sort of adapter perhaps?
You have a cyclocross bike. There is no reasonable way to add caliper brakes to that rear end, and probably the fork as well. Even if the frame was modified by bonding in a brake mount for a recessed nut, the reach of the brake that came with your group will be way too short, presuming it's a typical short reach road brake.
Low profile, smooth post cantis like you have are infamous for their finicky adjustment and tendency to squeal. If you want to modernize the bike, there are far nicer brakes you could get.