First Ride Review: Introducing Shimano GRX Mechanical 12-Speed Components – Josh Weinberg | The Radavist | A group of individuals who share a love of cycling and the outdoors.

Today, Shimano released the long-awaited mechanical 12-speed versions of their popular GRX gravel-focused drivetrain. With three 12-speed varieties to choose from (two 1x configurations and one 2x) and a list of desirable accouterments (optional dropper lever, interchangeable derailleur cages, refined wheelsets, updated ergonomics, and more), Shimano is covering a lot of ground in this new generation of gravel components. Josh recently had a chance to click through and pedal the wide range GRX RX820 groupset and, below, details the full product launch along with his first ride review…

I’m not sure if I remember any product(s) being rumored and leaked so much before launch as with GRX 12-speed. We’ve known it was coming but, until today, the extent of the launch was unclear. And I had questions:

Would it be mechanical or electronic shifting? Mechanical/cable brakes or hydraulic? Would they make existing MTB mechs compatible with drop bar levers or would it be something new?

Today’s full release seems to offer an exciting mix with a fair amount of cross-compatibility that incorporates current products like MTB cassettes, chains, and rotors with new derailleurs, levers, brakes, and wheelsets. Let’s take a close look at each of the three new mechanical 12-speed GRX options below.

GRX 1×12 with 10-45T Cassette

Paired with the RD-RX822-GS medium cage rear derailleur, which is designed for use with the 10-45T cassette, this drivetrain option is similar to its 11-speed predecessor but with an expanded range and additional cog. It’s designed for riders who want closer gear steps and aren’t riding on steep terrain with loaded bikes. Interestingly, in a first for Shimano, the cage of the RX820 rear derailleur is interchangeable with the long cage RX822 mech described below, meaning that you can swap between cassettes depending on the type of riding you’re doing. Additionally, cassettes and chains for this system are the same M8100 series that have been around since the beginning of Shimano’s entry into 12-speed mountain products.

Full groups with drivetrain, brakes, chain, etc will range between $1,572 and $1,542.

FC-RX820-1 Crankset

1×12-speed gearing
Crank arm length: 170 mm, 172.5 mm, 175 mm
Chainring options: 40T, 42T
SHIMANO HOLLOWTECH II construction
655 grams (172.5 with 40t chainring)
$249.99

RD-RX822-GS Rear Derailleur

SHIMANO SHADOW RD+ Chain Stabilization
Max cassette range: 45T
Interchangeable, replaceable GS/SGS derailleur cage
290 grams
126.99

CS-M8100-12 Cassette

Freehub type: MICRO SPLINE
10-45T range
461 grams
$164.99

GRX 1×12 with 10-51T Cassette

In perhaps the most exciting reveal of this new product lineup, GRX finally gets low gears to a 51T cog. While their 11-speed counterparts have been lauded for durability, ergonomics, and shifting performance, many riders found the max 11-46T range rather limiting. Now, Shimano has firmly entered the wide-range game with a long cage RX822 derailleur compatible with their 12-speed 10-51T mountain cassettes. This functionality is possible, in part, by incorporating MICRO SPLINE mountain bike hub technology to gravel with both 1×12 mechanical GRX setups. The MICRO SPLINE aluminum freehub design integrates with 10-tooth top gears and features smaller, more widely spaced splines that help limit cog damage over time. Currently, only two chainring sizes are available from Shimano for the RX820 cranks (40T and 42T), but hopefully they will be expanding the range soon. For now, Shimano there is a 38T chinring from the 610 series cranks (described below) that is coompatible. Also, we have confirmed Wolf Tooth will have both smaller and larger rings available shortly. For bikes with boost spacing, you can run an MTB (XT, XTR, etc.) crankset along with the new RX822 derailleur and 12-speed levers for a wide-range mechanical dropbar MTB.

Full groups with drivetrain, brakes, chain, etc will range between $1,572 and $1,542.

RD-RX822-SGS Rear Derailleur

12-speed
SHIMANO SHADOW RD+ Chain Stabilization
Max cassette range: 51T
Interchangeable, replaceable GS/SGS derailleur cage
288 grams
126.99

FC-RX820-1 Crankset

1×12-speed gearing
Crank arm length: 170 mm, 172.5 mm, 175 mm
Chainring options: 40T, 42T
SHIMANO HOLLOWTECH II construction
655 grams (172.5 with 40t chainring)
$249.99

CS-M8100-12 Cassette

Freehub type: MICRO SPLINE
10-51T
470 grams
$164.99

GRX 2×12 with 48/31 Chainrings and 11-34T or 11-36T Cassette

Don’t worry, Shimano didn’t forget about the 2x disciples looking for an ultra-wide gear range in this launch. For those seeking tighter rear cassette gear steps for more subtle cadence changes, the new 2×12 RX820 drivetrain utilizes gravel-optimized 48/31 front chainrings paired with an 11-34T or 11-36T cassette. Rather than MICRO SPLINE compatibility like the 1×12 options, however, the 2×12 cassettes interface with most existing 700c wheels thanks to use of the established HG freehub body design.

Full groups with drivetrain, brakes, chain, etc are $1,585.

FC-RX820-2 Crankset

2×12-speed gearing
Crank arm length: 170 mm, 172.5 mm, 175 mm
Chainring combination: 48-31T
SHIMANO HOLLOWTECH II construction
721 grams (172.5 with 48/31t chainrings)
$249.99

RD-RX820 Rear Derailleur

12-speed
SHIMANO SHADOW RD+ Chain Stabilization
Max cassette range: 36T
270 grams
$126.99

FD-RX820 Front Derailleur

2×12-speed
Toggle link construction offers more cable routing options
Wider tire clearance
- Chainline +2.5mm vs. conventional road FD
Precise and easy adjustment with integrated cable tension adjustment
95 grams
$61.99

CS-R8100-12 and CS-HG710-12 Cassette

CS-R8100-12 range: 11-34T
- 345 grams
- Freehub type: HG and HG L2
CS-HG710-12 range: 11-36T
- 391 grams
- Freehub type: HG and HG L2
$87.99

Updated Ergonomics and Brakes

The new GRX shift/brake levers have undergone some ergonomic improvements from their 11-speed counterparts while reportedly retaining the smooth and snappy shifting Shimano is known for. Optimized for use with both standard and flared dropbars, Shimano claims that by reducing pressure points and increasing surface area, riding with the updated levers will result in less hand fatigue while improving control and handling. Additionally, the new 1×12 groups carry over functions for the left lever first introduced with the original GRX: a brake lever-only model and a dropper-specific option that seamlessly integrates braking and dropper post-actuation.

The new ribbed-textured hood surface boasts better grip in rugged terrain. And, interestingly, blades on the RX820 levers feature an anti-slip coating; a technology borrowed from Shimano’s fishing equipment side of the business. Similar to their 11-speed counterparts, these brakes are hydraulic and there is currently no option for mechanical calipers. For the new brake sets, Shimano redesigned the rotor carrier out of shaped aluminum, an update that is purportedly shown to reduce the heat distortion that leads to a pronounced rubbing noise while breaking at speed. Additionally, calipers have 10% wider pad clearance to further decrease rotor noice.

Brake assembly pairs with dropper levers are $864.99 and 829.99 as levers only.

ST-RX820-R/L – Hydraulic Disc Brake DUAL CONTROL Lever

Gravel-specific brake lever and bracket ergonomics
Optimized for use with flared handlebar
Anti-slip coating on brake lever surface
Light and responsive mechanical shifting
5 grams (2×12 ST pair)
2 grams (1×12 ST pair)

ST-RX820-LA – Hydraulic Disc Brake and Dropper Lever

Left side brake and dropper post lever
Gravel-specific brake lever and bracket ergonomics
Optimized for use with flared handlebar
Anti-slip coating on brake lever surface
263 grams

BL-RX820-L – Hydraulic Disc Brake Only

Left side brake lever
Gravel-specific brake lever and bracket ergonomics
Optimized for use with flared handlebar
Anti-slip coating on brake lever surface
222 grams

GRX RX610 Components

Shimano is also introducing a selection of 12-speed GRX components for more budget-focused builds. While these will likely be found offering a wider price range on new complete bikes, it’s nice to see trickle down technology as part of this larger product launch. Notable features include:

Textured hoods and anti-slip brake lever coating.
New cranksets offer gearing options that specifically cater to the demands of gravel riding.
RX610 2×12 crank features 46/30 chainrings and comes available in 165 mm, 170 mm, 172.5 mm, and 175 mm crank arm lengths.
The RX610 1×12 crank has the same four crank length options and is available with highly durable steel 38T (a new option) and 40T chainrings to pair with a 10-45T or 10-51T cassette.
Complete groups retail for $1,165.92 for 1x and $1,233 for 2x.

These graphics show the current and new products as part of the GRX ecosystem

FC-RX610-1 Crankset

1×12-speed gearing
Crank arm length: 165 mm, 170 mm, 172.5 mm, 175 mm
Chainring options: 38T and 40T
815 grams (with 40t chainring)
$159.99

FC-RX610-2 Crankset

2×12-speed gearing
Crank arm length: 165 mm, 170 mm, 172.5 mm, 175 mm
Chainring combination: 46-30T
815 grams (with 46/30t chainrings)
$159.99

ST-RX610-R/L – Hydraulic Disc Brake DUAL CONTROL Lever

Gravel-specific brake lever and bracket ergonomics
Anti-slip coating on brake lever surface
Light and responsive mechanical shifting
611 grams (2×12 pair)
- $679.98
542 grams (1×12 pair)
- $664.99

BL-RX610-L – Hydraulic Disc Brake Only

Left side brake lever
Gravel-specific brake lever and bracket ergonomics
Anti-slip coating on brake lever surface

RX880 Carbon Gravel Wheels

And, last but not least, what would a complete group launch be without an accompanying wheelset? Along with GRX mechanical components, Shimano is also introducing an updated carbon gravel wheel that’s reportedly purpose-built to handle the rigors of dirt road riding. The new RX880 wheelset is a 64g lighter per pair than its predecessor and features the same shallow 32mm rim height. The RX880 wheels are tubeless-ready and with a 25mm inner rim width that’s suitable for tires from 32mm to 50mm wide.

User-friendly compatibility is further enhanced via a revamped “direct engagement” hub design, borrowed from DURA-ACE wheels, that easily converts between Micro Spline and HG L2 12-speed freehub bodies. It features quick and efficient engagement for rapid acceleration no matter the riding surface.

WH-RX880-TL Carbon Tubeless Wheels

DIRECT ENGAGEMENT freehub
Rim height: 32 mm
Internal width: 25 mm
Full carbon rim
Recommended tire size: 32-50 mm
Replaceable freehub body – switch between MICRO SPLINE and HG L2
- Note: Not compatible with 11-speed HG cassettes
1394 grams (MICRO SPLINE)
1397 grams (HG L2)

GRX 12-speed First Ride Review

My first ride with GRX 12-speed was just that: one ride. We were planning to spend multiple days with the components, but intense wildfire smoke in southern Oregon cut our time short. So it goes these days. But I do have a group in for longterm review and look forward to evaluating it both individually and against the Campy/Ingrid drivetrain I’ve been using on my Amigo Bug Out for the past year. Where I live in southern Arizona, with flat valleys surrounded by steep mountains, a wide range 1x drivetrain is necessary. I’ve had another bike set up with GRX 11-speed for a while now and, due to the terrain I typically ride, the 11-48T cassette isn’t enough. To that end, I also think 40 and 42T GRX chainrings currently being offered by Shimano aren’t adequate in this expansive product launch, so I hope to see more sizes available in the future. For my review, I’ll be using either a 36T or 38T ring from Wolf Tooth.

In my limited time riding with this new group, I found it to shift similarly to GRX 11-speed but with noticeable improvements to lever hood/body ergonomics. The ergo updates seem to make quite a difference in both comfort and control on and off road but, of course, the most meaningful evaluations will come on longer rides. With the dropper lever functioning similarly to the new MicroSHIFT Sword lever (with the lead cable end situated in the lever and a knarp/ferrule at the dropper) I’ll be testing its performance against my hacked Campy Chorus lever also described in my Bug Out review linked above.

Of course, I must relate my disappointment for lacking support of a mechanical brake option with this groupset. While I have never experienced a problem with any of Shimano’s hydro brakes in the past, mechanical brakes matched with a mechanical drivetrain is a priority for a lot of riders, particularly those that spend a lot of time in the backcountry. On the other hand, I appreciate that Shimano launched this mechanical group in advance of an electronic equivalent that has a bunch of features riders have been asking for with competitive pricing. Further, the ability to change out a derailleur cage for use with different sized cassettes is desirable feature and one I look forward to testing, as Shimano hasn’t yet released any information about how this is actually accomplished.

For myself and a few others, we experienced minor cable tension issues about 30 miles into our 40-something mile ride. With such a short distance it’s impossible to know if this was because the cables and housing weren’t cycled through (pre-stretched) at time of install or if the overall system is just sensitive due to cable pull ratio and close steps throughout the compact gear range. This is another aspect I plan to monitor closely during my long-term review.

It’s been a long week and my brain is mushy, so it’s possible I missed some important information and insights here. Drop your questions/feedback in the comment section below!