Times were that a new standard in cycling tech warranted an entirely new bike. That's still the case with some things (axle types, we're looking at you), but TRP's HY/RD Flat Mount Disc Brake Caliper bumps a standard set of cable brake levers up to hydraulic disc functionality. The caliper is compatible with most current generations of cable-actuated Shimano and SRAM shift/brake levers, so chances are good that it already works with your current drivetrain. The calipers relocate the hydraulic reservoir from the levers to the brake itself, reducing cockpit clutter and keeping the hoods nice and sleek. The HY/RD features automatic pad wear adjustment so braking is always consistent and it uses pads that are compatible with Shimano M525/M515 brakes, so replacements are always easy to find. The HY/RD comes with semi-metallic pads that work well in dry conditions but may wear quickly in wet/muddy conditions. If you plan on CX riding an upgrade to full metallic is recommended, but they will be slightly louder. You can chose 160mm or 140mm rotors, though TRP recommends always running 160 up front.