Shimano

GRX RD-RX812 Rear Derailleur

What Our Gearhead® Experts Are Saying:

"I switched to the GRX RX812 for my 1x gravel rig and haven’t looked back. The clutch keeps my chain tight over chunky descents, and shifting stays smooth even when my drivetrain’s covered in dust and mud. It’s basically MTB toughness adapted perfectly for drop bars."

From washboard descents to rocky doubletrack climbs, we rely on the Shimano GRX RX812 Rear Derailleur to keep our shifting crisp and our chain quiet. Purpose-built for gravel and adventure riding, this derailleur brings proven Shimano MTB tech into the drop-bar world, so we can charge harder without worrying about dropped chains or ghost shifts.

The RX812 uses a clutch-based Shadow RD+ design to maintain consistent chain tension, especially when the terrain gets rough. It's optimized for a 1x11 drivetrain with an 11–42t cassette range, giving us simplicity up front and plenty of gearing in the back. Whether we’re racing a gravel grinder or tackling a weeklong bikepacking route, this derailleur delivers smooth, reliable performance with zero drama.