Being the first kid in the sandbox can be a big deal in the bike component industry, and Shimano has claimed exactly that with their new gravel-specific groupset. Most drivetrain manufacturers have components designed for offroad riding, but the new Shimano GRX 800 gravel kit is the premier offering for the burgeoning dirt-road genre.
So what has Shimano changed to optimize this gruppo for grinding that gravel?
Cranks
To accommodate various styles of gravel-specific bikes, the GRX cranksets and front derailleur come with a +2.5mm chainline for increased tire and frame clearance. Double ring setups will work well for fast racing and heavier touring gravel-whips alike, while the single-ring version simplifies shifting activity and frees up your left hand for Shimano’s RX810 STI-style dropper post lever.
Cranks will be available in the top-shelf RX800, and a more affordable RX600 series, with all components interchangeable between two. Either series can be purchased in 1×11, 2×11, 1×10, or 2×10 configurations. Shimano recommends pairing their new drivetrain bits with an existing mountain bike or road cassette and chain that best fits your gearing needs.
Rear derailleur
New GRX derailleurs look like svelte versions of an XTR mechanism from the recent past, including a clutch system called SHADOW RD+ “to manage ‘chain chatter’, minimize unnecessary derailleur arm movement and provide uninterrupted shifting performance.” Alongside all of that chain chatter silencing, you can have the new derailleur with Di2 electric servos if you like. I think they could have named the electric version with a nod to the Flintstones, like “Robopebble,” but the marketing department forgot to call me before the new gruppo dropped.
Hydraulic brakes
The gravel gruppo’s hydraulic disc brakes are available in four different lines. The RX815 utilizes the same servo-wave tech that many riders love in Shimano’s mountain bike brakes, while the RX810, RX600, and RX400 offer stopping characteristics similar to Ultegra and 105 disc road options.
Wheels
Lastly, the new GRX kit includes a fresh set of Shimano hoops, designed with full days of grind in mind. “Shimano tips its cap to the experimental spirit of gravel with two gravel/adventure-inspired 12mm E-THRU axle wheelsets. The 700c or 650b (non-Boost) tubeless-ready wheelsets offer an optimal balance between weight, stiffness and gravel durability, bringing a wider 21.6mm inner rim width (comparable with MTB XC wheels) and an offset rim height of 22mm.”
Mechanical groupsets will be available in July in the EU and USA, and Di2 will hit the shelves in August. The sub and dropper levers should be available in September.
