Shimano GRX Di2 2x 12-Speed Review
“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. ” – https://gravel.shimano.com
“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.”
Shimano GRX Di2 2x 12-Speed Review Video
Alternative Video Link for those reading via email subscription
In this video, JOM of the Gravel Cyclist provides his long term review of Shimano GRX Di2 2x 12-Speed semi-wireless shifting and braking system.
Continued from Above:
“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.”
Shimano GRX Di2 2x 12-Speed Riding Experience
The jump from GRX Di2 11 speed to GRX Di2 12 speed is more of an upgrade to the drivetrain being completely honest, and those riders on 11 speed GRX Di2 may struggle making the leap, because 11 speed GRX Di2 is already so good. Haters will dislike the semi-wireless architecture of 12 speed GRX di2, but I love it, it guarantees long battery life, and the only inconvenience is initial setup if you happen to build your own bike, running a wire from each derailleur, to connect to the internal seatpost battery. That’s a moot point for many riders, as they aren’t exactly building bikes themselves.
In my experience pounding on this groupset for over six months, it is as bulletproof reliable as the 11 speed version, and shifting speed from pushing a button to gear shift execution seems on par, at least with my naked eye, of a wired 11 speed GRX Di2 groupset.
While I haven’t intentionally crashed the drivetrain, I have had some experience with crash mode on the 11 speed version, but the 12 speed variant has shrugged off every type of terrain I’ve thrown at it, with zero complaints. I expect durability is at least on par with the 11 speed version. It just shifts gears no matter what, even in the worst of mud and sludge. Additionally, I do like the aesthetics of the new rear derailleur.
Shimano provide an 11-36 12 speed cassette for this drivetrain, and its ratios are very very good. Typically, I use an 11-32 with my 11 speed GRX Di2 setup, but that additional 36T cog, so handy, and more versatility with the 12 speed version. Big positive, Shimano is charging a reasonable sum for their 12 speed cassettes, you won’t find any crazy $600 cassettes around here. However, Shimano needs a serious ding in this review, for not offering an 11-40 12 speed cassette, which this drivetrain is screaming out for.
The GRX 12 speed Di2 front derailleur is a powerhouse, and combined with Shimano’s excellent 2x 12 speed chainrings, absolutely bulletproof front shifting at the speed of near light, as I demonstrate in the video above. I have yet to drop a chain, and I doubt you will, unless you’ve knackered the installation.
The GRX 12 speed crankset isn’t winning awards for its looks, and I am a little disappointed Shimano left this crankset unchanged from the 11 speed version. However, I have racked up a crap ton of miles / kms on the 11 speed version, and what these cranks lack in beauty, they make up for in durability. On the positive, at least you can upgrade to 12 speed easily with a chainring swap. The omission of a GRX power meter isn’t something I’m concerned with, but some folks are disappointed, they may need a hug.
The revised brake hoods of the 12 speed variant are very comfortable, but I prefer the 11 speed shape due to the smaller top hook of the lever hood. Riders with larger hands may prefer the 12 speed version, but realistically, no complaints here. Something else worthy of mention, there is an LED on the front of each shifter that indicates battery life. If you hold both shifter buttons on each shifter at the same time, the LED lights up, green for 11% to 100%, and red for 1% to 10%. You can also see this battery status inside the eTube app.
System battery life has been very good. I haven’t been closely logging how many miles or kilometres between a recharge of the internal seatpost battery, but easily over 1,500km per charge, but that will depend on where you live, terrain you ride, and especially number of shifts of the front derailleur.
I love the customization options of eTube as they relate to the shifter buttons, a few of which I demonstrated with my personal configuration in the video above. The Shift Next feature for front derailleur shifting is ace. However, I do hope Shimano sorts out wireless updates of the shifters. Running a cable to the shifter for a firmware update seems out of place with the advanced nature of the system.
The revised brake calipers versus the 11 speed version are a nice update, particularly the additional 10% of pad clearance. I’ve yet to see a perfectly straight brake rotor out of the box, so this feature helps account for that a little. I mentioned it earlier, these brakes are just so so good.
I don’t cover GRX’s own 12 speed carbon wheels in this review, but I did review the 11 speed variant of those wheels. Honestly, the 12 speed version is pretty much the same, on terms of weight, and a few minor tweaks. You can see my review of the original grx carbon wheels linked here. I spent time riding this groupset with Shimano’s GRx 12 speed carbon wheels, and a high zoot DT Swiss GRC 1100 Dicut wheelset.
Overall, Shimano’s GRX Di2 2x 12 speed is a superb groupset, undoubtedly the benchmark 2x option for an electronic groupset designed for the rigors of gravel cycling. More of an upgrade from 11 speed than an outright new groupset, it is still a worthy upgrade if you’re on 11 speed GRX Di2. Bonus, Shimano’s 12 speed cassettes will work on 11 speed cassette bodies.
Reminder: ALWAYS BE A STEWARD FOR GRAVEL CYCLING: Respect the roads, respect the locals, respect the land, respect your fellow cyclists.
Learn more at the Shimano Gravel Website
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Links of Interest:
- Shimano Gravel Website
- Framework Bicycles Website
- Framework Bicycles Custom Gravel Bike Review
- Shimano GRX 12-Speed Mechanical: Bigger Cassettes, More Range
- Better Shifting Website
- Shifting Big Gears with Shimano GRX: 2x 48/31 with 11-40 XTR Cassette
- 2023 Rock Cobbler 10.0: Bakersfield, California
- Surviving Stetina’s Paydirt: Fractured Ribs & Clavicle Injury!
- Shimano GRX Carbon Gravel Wheels (11-Speed) Review
- North Florida Freeride Gravel Series
- How to Create Amazing & Fun Gravel Routes!
- Gravel Cyclist’s Route Library
- Gravel Bike Tire / Tyre Pressure Recommendations
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Does this lockout the 2 small cogs on the cassette so they can’t be used with the small ring on a 2X set up? I like that feature for running 11×40 cassette which unfortunately isn’t available in a 12 speed Shimano Cassette at this time – if it was I might consider moving from my GRX 11 speed Di2 at some point but without it I’ll stick with 11 speed.