As gravel has emerged as its own definitive segment, at times it has been a challenge for riders to decide which components to outfit their bike with. The options were out there, but nothing that was solely dedicated to gravel riding and racing, which left riders choosing between a road groupset, a dedicated cyclocross groupset, or a mixture of components that even included mountain bike parts. Fortunately, Shimano spent the last two years developing the new GRX group that's specifically designed to tackle dirt roads and singletrack on drop-bar machines, and they incorporated plenty of feedback from dedicated gravel racers and enthusiasts in the process. The GRX ST -RX600 STI Shifter & Disc Brake Caliper are a key component of the new group, and are positioned just below the premium RX810 levers, representing a more cost-effective approach that still gives you gravel-inspired ergonomics and superior braking performance. The RX600 mechanical shifters are largely similar in design to Shimano's current road shifters, offering the same light shifting action that rider's have come to know and love. The changes lie in a refined lever shape that improves comfort for mixed terrain riding, as well as a textured anti-slip surface on the levers that improves braking grip and control. The RX400 hydraulic calipers are effectively the same as Shimano's flat-mount road calipers, delivering powerful braking performance with heat-dissipating Ice Tech brake pads, as well as simple set up and maintenance thanks to One-Way Bleeding technology.