Could Shimano's new gravel-optimized electronic drivetrain technology make it to their mountain bike line?



Electrifying Shimano’s 12-speed gravel component family, the new 2 x 12-speed GRX RX825 Di2
components combine Shimano’s unrivaled electronic shifting with optimized gearing options for riding,
racing, and all-day adventures. The new suite of electronic Di2 parts features dual control levers refined
for comfort and control, a SHIMANO SHADOW RD+ equipped rear derailleur for better chain
management, and a gravel-optimized front derailleur for precise shifting.



Designed for gravel riders who live to be in the moment, who venture down lonely, unknown dirt roads,
who take on routes and races with unpredictable outcomes, Shimano GRX 12-speed Di2 delivers precise,
reliable, distraction-free performance in all conditions.

• Evolved Di2 Platform – Redesigned Di2 system with fast, precise shifting and a wireless cockpit
design for the ultimate performance and absolute reliability.
• Advanced Gravel Drivetrain – Optimized 12-speed gearing for unrivaled efficiency and
Shimano’s proven HYPERGLIDE+ technology for seamless shifting, no matter the situation.
• Refined Interface and Ergonomics – The ultimate balance of comfort and grip, GRX offers
unparalleled ergonomics, a cleaner cockpit design, and ultimate customization.

Electrified 2 x 12-Speed GRX Gearing Options
Shimano’s new suite of gravel components brings an electronic shifting option to the 2 x 12 GRX group
that launched last year. Pairing the new GRX RX825 Di2 shift levers, available satellite switches, front
derailleur, and rear derailleur with existing RX820 crankset, cassette, and brakes, riders will enjoy
Shimano’s hallmark Di2 shifting performance and reliability with 2 x 12-speed gravel gearing.

Like with the RX820 mechanical components, riders can tailor their gearing with the 48/31-tooth chainrings or opt to use the RX610 crank and its 46/30-tooth chainrings. Similarly, riders can choose from an 11-36T or 11-34T cassette for a wide gear range with tight gear steps so they can spin a comfortable cadence.

GRX RX825 Di2 compatible gearing options:
• 48/31T RX820 crank
• 46/30T RX610 crank
• 11-36T HG710 cassette
• 11-34T R9200, R8100, R7100 cassettes

Any of these gearing combinations pairs with Shimano’s latest carbon gravel wheels, the WH-RX880.
With 25-millimeter internal width and updated DIRECT ENGAGEMENT freehub, the RX880 wheels
provide a vital connection between rider and road, however remote or rugged.

Unrivaled Shimano Di2 Electronic Shifting for Gravel
Like its 12-speed DURA-ACE, ULTEGRA, and SHIMANO 105 Di2 siblings, the new GRX Di2 system is wired where it makes sense, featuring a central, multi-port battery that supplies stable, long-lasting power to both front and rear derailleurs. Smaller diameter wires connect directly from the battery to each derailleur, eliminating the need for junctions and streamlining the build process. The central internal battery also simplifies charging and remains secure over the roughest roads, trails, or whatever less traveled path a rider may choose.


Shimano Di2 Wireless Cockpit
Shimano’s 12-speed GRX Di2 features a wireless gravel-specific cockpit where raised hoods with ribbed
surface texture and anti-slip brake levers provide ultimate hand security no matter how spicy the ride
gets. That secure hand position is enhanced, as it was with the original GRX RX815 Di2 DUAL CONTROL LEVERS, with the location of the third Di2 button on the inside of the hood. Whether used as another shift location or for scrolling through screens on a cycle computer, this third
button is another way to fully experience Shimano’s electronic Di2 system.

Flared For Gravel
The new dual control levers also employ a gravel-optimized body shape cross-section for seamless
integration with flared handlebars. Rounder in shape, the transfer from handlebar to hood is smoother
and creates a larger surface area to help eliminate pressure points.

ST-RX825 – Hydraulic Disc Brake DUAL CONTROL Lever
• Wireless Di2 Connectivity
• 2 x 12-speed Dual-Control Lever
• Gravel-specific brake lever and bracket ergonomics
• New flared drop bar optimization
• Anti-slip coating on brake lever surface
• Three Di2 buttons per lever for E-TUBE PROJECT
Cyclist app customization
• Replaceable coin cell batteries (2 x CR1632) with
expected lifespan of 3.5 to 4 years
• Weight: 415 grams / pair

Accessory Di2 Shift Switches
The new Di2 system also allows for accessory shift buttons, another key advantage of electronic shifting. Plugging in one of Shimano’s satellite shifters, whether on the tops, drops, or on aero bars, riders can more consistently maintain their effort without the need to move their hands. Like the third button on the GRX Di2 dual-control levers, these satellite switches can be assigned various functions including shifting of either derailleur, to control compatible lights and cycle computers, or as a lap button during workouts.

SHIMANO SHADOW RD+ Rear Derailleur
The RX825 rear derailleur features Shimano’s pioneering SHADOW RD+ technology. With its convenient on/off switch, SHADOW RD+ makes removing the rear wheel easy when turned off. When on, the drivetrain is under additional tension that makes for a quieter ride and more precise shifting.
Like on Shimano’s road 12-speed Di2 systems, the rear derailleur is also the communication hub of the
drivetrain, communicating wirelessly with the shift levers, compatible cycle computers, and E-TUBE
PROJECT Cyclist via a smartphone. It also houses the system’s charge port and the multi-function button which allows riders to easily check battery level, pair via Bluetooth, and enter adjustment mode for both derailleurs.

RD-RX825 Rear Derailleur
• SHIMANO SHADOW RD+ Chain Stabilization
• Integrated D-FLY connectivity and charging
• 12-speed
• Compatible with 11-34T and 11-36T cassettes
• Weight: 310 grams

Wider Chainline for More Clearance
Like the very first GRX groups, the RX825 system employs a wider, +2.5mm chainline for improved tire
clearance. This is especially helpful with the trend towards wider tires and events where mud is

FD-RX825 Front Derailleur
• Chainline +2.5mm vs. conventional road FD
• Wider tire clearance
• 2 x 12-speed
• Weight: 142 grams


Using Shimano’s E-TUBE PROJECT Cyclist application, riders can choose between different gear shift
intervals for multi-shift, customize shift button assignment (what buttons perform which functions),
program different automatic shift modes like Synchronized and Semi-Synchronized shifts, and fine-tune
shifting. The launch of RX825 also coincides with the debut of Shimano’s new FRONT SHIFT NEXT functionality. With this firmware update, you can now utilize Shimano’s user-friendly E-TUBE PROJECT Cyclist app to program any 12-speed Di2 button to shift the front derailleur to whichever chainring you are not currently using and then toggle back and forth using the same button. This new firmware is compatible not only with GRX RX825, but also with Shimano’s family of 12-speed road Di2 groups. The result is simpler, more intuitive shifting for less-experienced riders and quicker decision-making for veteran riders in the heat of competition.

Along with dramatically simplifying the gear-changing process, Shimano FRONT SHIFT NEXT can also free up other switches to handle tasks such as moving through multiple screens on a paired cycle computer, turning on and off compatible lights, or hitting the “lap” button on your cycle computer so you can keep your hands securely in place, even during your hardest efforts.

For more information, please visit:

You might also like