Over the past several seasons, the flat-mount standard has proven to be the predominate "new-normal" mount on road, gravel, and 'cross framesets. So if you've got a perfectly good SRAM Force hydro group with older post-mount calipers and you're looking to build up a new frameset using a flat-mount standard, invest in the SRAM Force 22/Force 1 Flat Mount Caliper, and with a quick bleed, you'll be good to go for transferring your group over to the new ride. Yes, we're quite familiar with the adapters out there that allow you to use your post-mount calipers on that flat-mount frameset, but honestly, it looks horrible, and by placing the calipers so far away from the fork leg and chainstay, we'd venture to say that it muddies up the aerodynamics quite a bit too. And, we're not fans of using adapters for adapting sake if viable options exist and besides, were fairly certain our ride could use some new pads and a fresh bleed anyways.
The biggest advantage with the flat-mount standard is its simplicity allowing for a sleek design that saves weight and provides a better interface for more powerful and better-modulating brakes. The front caliper requires an adapter that can be oriented in two directions for either 140 or 160mm rotors, while the rear caliper attaches directly to the frame's chainstay for 140mm native use or you can use a small adapter for 160mm rotors. This serves to clean up the appearance department and it offers some claimed aerodynamic benefits. While we can't verify the claim of less drag by the seat of our cycling shorts, it certainly makes sense as the closer the caliper sits on the frame or fork, the smaller the footprint is to the wind. Now that many aero frames are coming equipped with disc brakes and citing nearly zero aero drag penalties versus its rim brake versions, we feel this claim holds water.
Besides losing the post-mount ears, the flat-mount caliper is virtually the same as the ones you plan to replace. It shares the same pads, bleeding technique and tools, and DOT brake fluid. Please note that flat-mount calipers will only work with 140 and 160mm rotors depending on which adapters are used.