Bikes and Tech
Shimano GRX is well suited to the OPEN U.P. carbon...

Inside the development of Shimano’s GRX gravel gruppo

Japanese company's new off-paved-road-specific component group aims to provide array of options for gravel and cyclocross riders

Dave Lawrence was on a shop visit in Minnesota in 2013 when he first got wind of the coming gravel cycling phenomenon.

“They told me about these meet-ups that were happening and how they were selling more cyclocross bikes in May than any other time of the year,” recalled Lawrence, Shimano North America’s road product manager. “One of those meet-ups was [the Almanzo gravel cycling event] and like 700 people had shown up that year. That got our attention and we knew we had to do a deeper investigation.”

A year later, Lawrence flew to Colorado for another series of shop visits, and spent some time riding road bikes off-road around Boulder and Golden. The stories heard and feedback gleaned were the same: At a grassroots level road cycling was in the midst of a fundamental change, with many riders gravitating to more versatile bikes with features such as more progressive frame geometry, wider gear ranges, and hydraulic disc brakes that allowed clearance for larger tires. And it was all being done in the name of riding road bikes off road, be it on gravel, singletrack, or somewhere in between.

Then in 2015, Lawrence and some of his Shimano engineering colleagues took what he calls a deep dive trip to Kansas, home to the famed Dirty Kanza gravel cycling event, which started in 2006 and has grown to 2,750 registered riders in 2019. There they started initial research and development on what would eventually become the Japanese company’s gravel-specific GRX gruppo that was released earlier this year. Shimano also began recruiting ambassadors for what spawned its Gravel Alliance, a group of 16 multi-surface-focused cyclists who served as both product testers and marketers as the company began releasing gravel-specific products.

The Shimano Ultegra RX rear derailleur was the company’s first significant foray into gravel componentry. Photo: Shimano

That unveiling commenced in earnest in 2018 at the Almanzo race/ride, where Shimano launched its RX rear derailleur, which like its mountain bike cousin, has a clutch mechanism that reduces unwanted chain movement, quieting the drivetrain on rough terrain. But RX, which was compatible with existing Shimano road groups, was just a bridge along the path towards the full gravel emersion that now permeates the entire drop bar-bike category. Indeed, that derailleur is now positioned as an aggressive road bike offering. If you really want to go all-in on drop bar bike riding on dirt (be it gravel or cyclocross), GRX is Shimano’s answer thanks to a new rear derailleur that’s more rugged by design, with bigger pulleys. But there is much more to this story.

That brings us to Whitefish, Montana, at the end of August this year when Shimano hosted a gaggle of cycling industry tech editors, providing the opportunity for first rides on its 800-series GRX Di2 electronic shifting drivetrain, which is the current pinnacle of the gravel-specific group, equating to an Ultegra-level offering. There is also a mechanical 800-series 11-speed groupset, along with a more budget friendly lower-tier 10-speed mechanical group.

The Shimano GRX group includes a wide array of gearing options for 1x and 2x drivetrains, including this 48-31 set-up with 11-34 cassette. Photo: Shimano

What was arguably most interesting about the experience was that each editor was given carte blanche in building up their test bike, helping illustrate the wide variety of choices GRX provides. Most of us trended toward gravel road-friendly, meaning 2×11 set-ups with wide gear ranges for climbing steep, loose terrain. On the VeloNews test bike, an Open U.P., the choice was a 48-31 chainring (the widest delta the company has ever made) paired with an 11-34 cassette, the rationale being that a 31-34 low gear will allow for easy spinning up most climbs, while the 48-11 won’t leave us spun out when bombing downhill.

Shimano also offers a 46-30 chainring option, along with 11-30 and 11-32 cassettes, allowing riders to prioritize gear range versus tighter gear steps. Additionally, they have the lower-priced 2×10 GRX group that comes with a 46-30 chainring combo that can be paired with 11-32, 34, or 36-tooth cassettes. All the GRX front derailleurs employ a +2.5mm chainline for increased tire and frame clearance. Just note that GRX front derailleurs must be used with GRX cranksets and vice versa.

The Whitefish area proved to be a great place for gravel road and trail riding. Photo: Shimano

“Gravel as a discipline is wonderfully democratic and we see a broad range of riders and bikes and backgrounds and experience levels,” explained Shimano North America Road Brand Manager Nick Legan. “We wanted to make sure GRX was attainable for almost anyone who was interested in gravel and that’s why it extends from the 800 series Di2 to a 10-speed series.”

GRX is also Shimano’s anointed group of choice for cyclocross, and thus includes a 1×11 option with 40- or 42-tooth front chainring that racers would most likely pair with an 11-40 or 11-42 cassette and the requisite longer cage rear derailleur. You could also use a shorter cage 2x rear derailleur on a 1×11 set up and pair it with an 11-30, 32, or 34 tooth cassette if closer gear steps were a priority and race course conditions would allow for the smaller gear range. In all cases, you’ll get the same clutch benefits that first appeared on the RX derailleur last year.

“GRX is really a story about options,” added Legan. “What someone may want or need for gravel riding on the West Coast may be different than the Midwest or East Coast. And what you need for gravel riding and racing is obviously different than cyclocross, so we needed to make sure there were a lot of different product options and we knew what we had before was not optimized for that. This isn’t a gimmick. We honestly believe this will be a sustained part of the market for years to come and are thus treating it that way.”

The new GRX hoods provide ample hand security when bombing down dirt. Photo: Shimano

Brake hood ergonomics and brake design are arguably the other most prominent features of the GRX group. Understanding that it’s one thing to plummet down a paved road, but an entirely different animal if that road is strewn with rough, loose gravel (or it’s a trail instead of a road), Shimano’s GRX dual control levers have a brake lever axis that’s 18mm higher than its road cousin. This provides more leverage when braking in the hoods, making it easier to stay there during situations where you might otherwise be forced into the drops to maintain control.

Additionally, the brake levers utilize a curved blade design and have an anti-slip texture that aims to further improve brake feel and power, while the accompanying PRO Discover Big Flare Handlebars have a 30-degree flare and are designed for seamless Di2 integration. The GRX Di2 levers also include additional buttons that can be programed as shifters or to flip through screens on your paired cycling computer.

The dropper post lever can be actuated with your thumb from the drops or index finger from the hood. Photo: Shimano

“The idea is that you can drop into the gnar and stay in the hoods, rather than feeling like you have to be in the drops, which would normally be the case,” explained Lawrence. “There’s also more hood purchase and texturing with GRX that’s meant to help provide a secure place for your hands.”

And if that’s not enough security, you can also add in sub levers (think MTB-style brake levers) that mount on the tops of the handlebars, giving you yet another way to slow down in those gnarly sections.

Other GRX-related options include a budget-friendly tubeless-ready aluminum wheelset that comes in 700c or 650b with a rim width of 21.6mm to accommodate wider tires. It’s also offering a 70mm travel dropper post that on 2x set-ups is controlled with a lever that’s attached to handlebars and can be actuated from the hoods or drops with your thumb or index finger. And if you go with a 1x set-up, Shimano sells a left side brake lever that will manipulate the dropper since you don’t need it for shifting.

The brake levers utilize a curved blade design and have an anti-slip texture that aims to further improve brake feel and power. Photo: Shimano

For our test bike, we went with 700c wheels for better on-road performance, and added the dropper post and sub levers because why the heck not.

Initial impressions of the group after a few shakedown rides in Montana were decidedly positive, but we’ll withhold making any definitive declarations until running it all through a longer test session. For now, let’s just say that Shimano has put a lot of time and thought into the needs of gravel and cyclocross riders, then done its best to provide a wide array of functional options.

“We decided it was really important to create a new set of components specifically for gravel and ‘cross,” said Legan. “We believe that there is enough differentiation from road riding to create a set of components for that world instead of an all things for all people option. GRX is really about providing choices and not a single solution.”