The RX822 sits at the top of Shimano's 12-speed mechanical GRX line, and the GS medium-cage version is the one to grab if you're building around a 10-45T cassette rather than the wider 10-51T range. This is a 1x-only derailleur — there's no clutchless option and no front derailleur compatibility built into the design brief — so it slots into the gravel racing and fast-adventure category rather than loaded bikepacking. Shimano borrowed the interchangeable cage concept from the mountain side, which means if your gearing needs change later, you swap the cage rather than the whole derailleur.

Shadow RD+ handles chain management. The clutch tensions the cage to keep the chain quiet over washboard, chunk, and drops, and the on/off switch lets you release tension for wheel removal without fighting the spring. It's the same principle Shimano uses on XTR and XT mountain derailleurs, adapted to the geometry of a drop-bar setup. Practical effect: less chain slap on rough descents, fewer dropped chains, and a quieter cockpit when you're actually paying attention to line choice instead of drivetrain noise.

Construction is aluminum body with fiberglass-reinforced composite outer plates and stainless steel hardware at the wear points. Four PTFE-coated pivot pins reduce friction through the parallelogram, which shows up as lighter shifting feel at the lever. Cage capacity is 35T total, which covers a 10-45T cassette with a single chainring — pair it with a 40T or 42T ring depending on how much top-end speed you want versus climbing gear.... Read More