Shimano GRX Di2 2x 12-Speed Review: Benchmark Shifting

"Electrifying Shimano’s 12-speed gravel component family, the new 2 x 12-speed GRX RX825 Di2

"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."

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.

Reminder:
ALWAYS BE A STEWARD FOR GRAVEL CYCLING: Respect the roads, respect the locals, respect the land, respect your fellow cyclists.

Chapters:
0:00 Introduction
1:25 Semi-Wireless
3:05 Why Not Full Wireless?
3:35 Redesigned Shifters
5:30 Satellite Shifter Buttons
6:35 Shifter Firmware Updates
7:58 Rear Derailleur RD-RX825
9:58 No 11-40 Cassette
11:22 Rear Derailleur Shifting Demonstration
11:48 Front Derailleur FD-RX825
12:20 Front Derailleur Shifting Demonstration
12:52 GRX 12-Speed Crankset
14:06 Hydraulic Brakes
14:39 Shifting Customization in e-Tube & Front Shift Next
17:24 GRX Di2 12-Speed Riding Experience
23:39 Closing
24:37 General Madness

Links of Interest:

Amazon Affiliation Link:

[tmfos]

A quality, balanced review from a straight-talking rider - nice to see kit being tested covered in real-world crap, not shiny-shiny-new as just received from the manufacturer's showroom/sponsorship department. Definitely happy with my choice so far for GRX RX 825Di2 even for a bike that'll be used 50:50 for gravel:road riding - thanks buddy great review!

[NBIgDEal]

Hey man, thanks for sharing the link to that absolute gorgeous frame! Thanks for making the video, love it!

[jonathanwoo]

The lack of a 12-speed 11-40 cassette is the reason why I'm still stuck on the 11-speed on my gravel bike, with the 11-40 cassette. I also prefer the gearing ratios of the 11-speed 11-40 for gravel (large 2T gaps on the higher gears). For my riding I shift less when the gaps are larger. I have the 12-speed group on my road bike and the gearing is fine, but I wouldn't like it for gravel. Shimano really missed a good opportunity for not having the 11-40.

[petersouthernboy]

I just love electronic shifting. It’s one of those things in life that once you try it - you’re hooked.

[christophericcio]

10-45 cassette with Wolftooth link, works just fine with GRX 12v for me. With 30-46 crankset.

[youriyimmek]

I love it. It is affordable, sustainable, easy to maintain, and compatible with other components and brands

[rykie]

Love your channel, and the and I'll always be a Sram fan until Shimano goes fully wireless.

[KoenMiseur]

Got this groupset on my new Gravel/winterroadbike, perfect for that, all the high and low gearing I need. It is a bit of an adjustment everytime I switch from my SRAM AXS bike to this, but these electronic groupsets all work so well!

[yugeno]

Having survived the 3x (and even 4x ) era, a quality 2x drive-train w/ a Type2 clutch RD is highly underrated. I'm still running a XX/X0 2x drivetrain on my OG Niner Air9 and it's rock solid. I am running a 1x on another newer bike and the bail-out gear is 'nice to have' when you 'need' it, but 26x36 has always been more than adequate (living and riding in Colorado) and I do get tired of always having to shift up and down and up and down the 12spd cassette.

[siy]

Thanks for the review John. Ben Delaney also noted that he preferred the 11spd shifters for the same reason. I'd add the 11spd look nicer. Shimano claim the 12spd handle area has a rounder profile to improve comfort with flared bars. Have you noticed a change in this area?
AirBike do a 12spd 11-42 when it's in stock. I doubt it shifts as well as a Shimano cassette and probably weighs a bit more too.
The Ultegra 12spd crank and front derailleur are aesthetically much slicker, IMO. Also lighter, and come in 160 and 165 options.
If someone is below 6ft they are better off on cranks 165mm or smaller, the fact that the GRX 820 cranks dont come any smaller than 170mm is kinda nonsensical.

[eltribun]

I would like to use my powe2max crankset 11speed with this group, could this be an issue in any way? a 12speed chain works on it as I already tested it.... Thanks from GER, nice review!

[bmwofboganville]

1x I'd rather have mechanical, 2x Di2. I think if you're going one chainring your bias is toward simplicity/robustness, two chainrings is for efficiency/speed. I hope Shimano continue to offer both.

[patrickrenschler]

I agree, a 11-40 cassette would really set this group apart and it's too bad shimano doesn't have one.

I also have a preference for more evenly spaced gears, shimano's cassettes space the high end closely and then space the low end further apart, I don't care to have 11-12-13-14-15 high end cogs, I'd rather have even jumps going through the full range.

[dvs]

If there is a 3rd port on the battery, a cable can be attached to it & the front shifters. They will be updated one at a time. I leave the cable covered & secured in my road frame & it's always there if an update is available thru e-tube.

[bubuTANK]

I would like to ask for your help, after the update, my shifting system did not shift to the smaller chainring on the first derailleur when going uphill, I don't know what the name of this function was.. but when going uphill, I shifted down a few gears and my derailleur automatically shifted to the smaller chainring in front. I have a GRX RX825 Di2 system 2x12... cranks (rx 825) 4.1.0 sw, front derailleur (rx825) 4.2.0 sw, rear derailleur 4.3.0 sw, bt-dn 300 battery has 4.2.0 sw version. Shimano GRX FC-RX820, 48x31T+Shimano 105 CS-HG710, 11-36T // cube nuroad c:62 race modell 2025.. Multi Shift is ON + SYNCHRONIZED SHIFT is on NORMAL.

[sccxvelo]

Spilt between grx 2x or sram axs or ratio tech upgrades to mechanical shifting. Looking at grx di2 for the 2x and braking coming sram 1x11 mechanical but the lack of the 40 or larger cog on cassette for range is the problem. Grx di2 12 speed max low ratio. 31 chainring / 36 rear cog = 0.86 compared to 0.78 ratio with the 40t rear cog available in 11speed for low end. On 1x setup 44 chain ring / 52 rear cog = 0.85 equals the12 speed version. Where 40t or 38t chainring will be lower ratio then the 2x11 grx. So grx di2 is not saving grams it is where the grams are at but limited low range with higher high ratio which is rarely used. When I can get ratio tech 12 speed shifter and rear derailleur cage upgrades for sram 11speed hrd for cheaper without charging worries. You miss at the high end still everything else is there. SRAM axs is 1x or it is same gear ratios on their 2x setup with 36t cog max in back too. So hard call which way to go.

[christwardzik]

Great video. Do you / anybody know how big grx will go on the crankset ? Is there a 50t option in their 2x chainring?

[liilli]

Even after the newly released SRAM RED E1, is the GRX lever still the best ergonomic lever?

[sabamacx]

I use wider Galfer 2mm rotors with this groupset and the brakes/calipers don't mind the wider rotors.

[bengt_axle]

Does LGC prefer ribbed or smooth (e.g. SRAM)? Or is it the girth that really matters?