Shimano GRX 12-Speed Mechanical Drivetrain in Detail

“With the introduction of Shimano GRX RX820 12-speed mechanical components, SHIMANO continues its legacy of innovation as the originator of gravel-specific components. Rooted in simplicity, reliability, and adventure, the new 12-speed GRX lineup delivers more gearing options along with unrivaled ergonomics so riders get the most out each unpaved adventure, wherever that might be.” – https://gravel.shimano.com

Shimano GRX 12-Speed Mechanical Drivetrain Video

Alternative Video Link for those reading via email subscription.

In this video, JOM of the Gravel Cyclist crew covers everything learned about the updated Shimano GRX 12-speed mechanical groupset, courtesy of a visit to Bend, Oregon, for the media camp.

Continued from Above:

“With a focus on the heart and soul of gravel cycling, Shimano mechanical GRX receives this 12-speed upgrade delivering top-tier performance without an over-the-top price. And since gravel is all about personal expression and freedom to choose how and where to ride, Shimano GRX includes three unique 12-speed mechanical drivetrain personalities to cover the full spectrum of riders and rides.”

Shimano GRX 1×12 with 10-45T

“Riders who love pushing for personal PRs or duking it out at the sharp end of a race will appreciate the gear steps of the RX820 1×12 UNBEATABLE setup with a 10-45 cassette paired with a 40- or 42-tooth chainring. Just like its 11-speed predecessor, RX820 delivers smooth, reliable shifting but now features a wider gear range and extra cog, making it easier to find the optimal cadence for maintaining your position in the pack.”

This setup employs the RD-RX822-GS medium cage rear derailleur designed for use with the 10-45T cassette and includes SHIMANO’s integrated SHADOW RD+ chain stabilizer, providing quieter shifting, and secure chain management in rough terrain.

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)

RD-RX822-GS Rear Derailleur

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

CS-M8100-12 Cassette

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

Shimano GRX 1×12 with 10-51T

“For all-day—or multi-day—adventures heavy on climbing, the new RX820 1×12 UNSTOPPABLE option features SHIMANO’s wide-range, 10-51T cassette along with a 40- or 42-tooth chainring. This setup delivers optimal climbing gears for the steepest jeep roads or high mountain ascents.”

“The UNSTOPPABLE 1×12-speed setup includes the RD-RX822-GSG long-cage rear derailleur with integrated SHADOW RD+ chain stabilizer that is optimized for use with the 10-51T cassette. New for this generation of GRX is the ability to change or replace the derailleur cage between 1×12 options. This means if you need to replace your cage or your gearing needs change, you don’t have to buy a whole new derailleur.”

“Additionally, Shimano brings its proven MICRO SPLINE mountain bike hub technology to gravel with both 1×12 mechanical GRX setups. This lightweight aluminum freehub design seamlessly integrates with 10-tooth top gears and features smaller, more widely spaced splines that limit cog damage over time.”

RD-RX822-SGS Rear Derailleur

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

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)

CS-M8100-12 Cassette

• Freehub type: MICRO SPLINE
• 10-51T
• 470 grams

Shimano GRX 2×12 with 48/31 & 11-34T or 11-36T

“For riders seeking the best of both worlds, the new 2×12 RX820 UNDROPPABLE drivetrain utilizes gravel optimized 48/31 front chainrings paired with an 11-34T or 11-36T cassette. This setup delivers an ultra-wide gear range for spinning a comfortable cadence when cruising the flats, smashing endless dirt road rollers, or tackling a massive backcountry climb.”

“This option delivers precise mechanical front and rear shifting and features integrated SHADOW RD+ chain stabilizer for ultimate drivetrain security over bumpy terrain. It maintains tighter rear cassette gear steps, ideal for subtle cadence changes during competitive racing and spirited weekend group rides. And the 2×12 setup seamlessly interfaces with most existing 700c wheels thanks to its use of the tried-and-true HG freehub body design.”

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)

RD-RX820 Rear Derailleur

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

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

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

Updated Ergonomics & Brakes

“GRX’s ergonomic distinctiveness continues with its redesigned shift/brake levers. Adding 12-speed shifting without any additional lever bulk, the RX820 series shifters are designed for all-day comfort when using flared drop bars, a gravel cycling staple. By reducing pressure points and increasing surface area, your hands will feel less fatigued, and you’ll be better in control as you test your limits.”

“The new GRX shift/brake levers offer light and responsive mechanical 12-speed shifting. While the left lever of the UNDROPPABLE 2×12 GRX group delivers Shimano’s unrivaled smooth front shifting, 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.”

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
• 572.5 grams (2×12 ST pair)
• 511.2 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
• Photos unavailable at this time.

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 820 Series Line-Up & Gear Ratios

Shimano RX880 Carbon Gravel Wheels

“Along with GRX mechanical components, Shimano is also introducing an updated carbon gravel wheel that’s purpose-built to handle the rough-and-tumble rigors of dirt road riding. The new RX880 wheelset is a full 64 grams lighter per pair than its predecessor and features the same shallow 32 mm rim height for faster acceleration and quicker climbing. The RX880 wheels are tubeless-ready and employ a progressive 25 mm inner rim width that’s suitable for tires from 32 mm to 50 mm 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. The RX880 hubs and rims are laced with 24 J-bend spokes front and rear that maximize strength and reliability no matter how adventurous your next ride gets. ”

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)

Shimano GRX RX610 12-Speed

“For the more budget conscious consumer and to allow a wider price range on complete gravel bikes, Shimano has also updated its 600-series cranks and shift levers for 1×12 and 2×12 setups that utilize trickle-down technology from the original 800 series GRX component line.”

“Top features include textured hoods and anti-slip brake lever coating that bolsters control on rugged terrain. The new cranksets offer gearing options that specifically cater to the demands of gravel riding. The RX610 2×12 crank features 46/30 chainrings and is 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.”

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

FC-RX610-2 Crankset

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

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)
• 542 grams (1×12 pair)

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
• Photos unavailable at this time

2x Weigh-In (sorry, 1x parts unavailable)

Additional Photos

Visit the Shimano Gravel Website for more information.

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Links of Interest:

• Shimano Website – https://bike.shimano.com
• Shimano Gravel – https://gravel.shimano.com
• Gravel Bike Tyre Pressure Guidelines
• Tailwind Nutrition (JOM’s choice of on-the-bike hydration)
• Gravel Cyclist’s Route Library

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