Building a gravel bike from the frame up means sourcing a dozen components that all need to work together, which is where a curated kit saves you the compatibility headaches. The Shimano GRX-RX825 Di2 2x12-Speed Kit bundles the shifting, braking, and drivetrain components into one package, leaving only the frame-specific pieces for you to source separately. You get the ST-RX825 hydraulic brake and Di2 shift levers, BR-RX820 calipers, front and rear Di2 derailleurs, a 12-speed chain, the 11-36T cassette, the internal Di2 battery, and the charging cable. What's not included: a crankset, bottom bracket, rotors, and the SD300 Di2 wires that connect the battery to the derailleurs.

The GRX RX825 shifters use wireless communication with the derailleurs, powered by CR1632 coin cell batteries that last three to four years under normal use. That eliminates the Di2 wires running from the cockpit down to the frame, which makes installation on bikes with integrated handlebars and internal routing significantly easier. Each lever has three Di2 buttons you can assign through the E-Tube Project app, and you can add satellite shifters on the tops or drops if you want more shift points. The hood shape has been refined for flared handlebars with a rounder profile that eliminates pressure points, and the anti-slip coating on the brake levers keeps your grip secure when conditions get wet or muddy.

The rear derailleur functions as the communication hub for the entire system, handling wireless pairing with the shifters, hosting the charging port, and running the multi-function button for battery checks and adjustment mode. Shadow RD+ technology adds a gravel-tuned clutch that maintains chain tension over rough terrain, with an ON/OFF switch for easy wheel removal. The front derailleur uses a +2.5mm chainline compared to road derailleurs, creating clearance for wider tires and reducing mud buildup around the chainstays. Both derailleurs connect to the BT-DN300 internal battery via slim SD300 wires that run through your frame.... Read More