It’s been a long time coming, but after teasing with Ultegra RX last year, it’s finally here, Shimano has announced its first dedicated groupset aimed at gravel and adventure bikes. Called GRX, the new offering provides a wide spread of possible builds including 10 and 11-speed, 1x and 2x, mechanical and electronic, wide or close-range gears and dropper post integration.
Shimano hasn’t just rushed into the gravel market. Oh no, that’s not the Shimano way. It has taken time to research, test and develop products that it feels meet the feedback it has been getting from riders around the world embarking on the new wave of adventure, bikepacking and gravel riding. And what it has developed is a groupset that is as adaptable as the bikes it’s designed for.
The GRX groupset will be offered in RX800, RX600 and RX400 series (800 being lighter and 11-speed) with 1x11, 2x11 and 2x10 drivetrains and mechanical and Di2 electronic shifting options so you really can pick a groupset configuration that meets your needs. Don’t like front mechs? Go 1x11. Prefer the wide range of a double chainset and want to stick with 10-speed? You can do that too.
“Developing the series took Shimano’s development team well outside traditional confines to create a platform that addresses riders’ needs now and into the future. Be it gravel riding, modern adventure road riding, bikepacking, or fulfilling the needs of discerning cyclocross racers, Shimano GRX provides options ranging from gravel-tuned gearing ratios to custom ergonomics, from dropper post integration to gravel-specific GRX wheels with wider rim profiles,” explains the company in its press release.
The new groupset includes cranksets, front and rear derailleurs, STI levers, a new sub-brake lever for braking on the tops, disc brake calipers and wheels. The top-end 800 series can be mixed with the more affordable 600 series components.
“This means that you can create everything from a light-weight racing-level GRX stead at the premium level to a leisure-riding GRX workhorse at the more economical level,” says Shimano.
Cassette and chain options will come from current road (105, Tiagra, Ultegra) and mountain bike (Deore, SLX, XT) groupsets.
Let’s look at the new groupset in detail and break it down into each component family.
There are three cranksets to choose from - 1x11, 2x11 or 2x10-speed - and each has a +2.5mm chainline for increased tyre and frame clearance.
The GRX double chainset is offered with 48/31 and 46/30t options with a 17 and 16t gap respectively between the two rings.
The single ring chainset employs Shimano’s Dynamic Chain Engagement tooth profile to prevent the chain bouncing off on rough terrain.
Claimed weights are as follows:
SRAM might be on a mission to kill off the front mech, but Shimano still firmly believes in the benefits it provides, and the new GRX groupset can be had with a front mech in either mechanical or electronic flavours.
Compared to regular road front mechs, the GRX front derailleur has an additional 2.5mm outboard clearance to provide space for wider tyres, up to 42mm.
For this reason the front mech must be used with the matching GRX chainset which is similarly pushed out by 2.5mm from the frame.
GRX front derailleur weights:
As you might expect, the new GRX rear mechs are based on the Ultegra RX mechs that were launched last year, and which gave the first indication Shimano was looking at the gravel and adventure bike market.
As such, the rear mechs use the company’s Shadow+ technology which helps to minimise chain slap provide more secure chain retention and a quieter ride.
There are four rear derailleurs wearing the GRX label, a short and long cage option in both mechanical and Di2. Short cage for 11-30/34t cassettes and long cage for 11-40/42t cassettes.
GRX rear derailleur weights
There are dedicated GRX levers, mechanical and electronic, which use a “gravel-specific ergonomic” lever design.
The hood shape is 18mm taller to provide a more secure hand position on rough ground, essentially to act as something to butt your hand up against to stop it sliding over the top of the hood, with a bigger scoop in the centre of the brake lever along with an anti-slip textured finish to provide a more positive finger/lever engagement.
If your gravel riding is getting rowdy and you want/need a dropper post, Shimano has developed a dedicated left-hand shifter that is compatible with cable-operated dropper posts with a 9mm lever throw.
There’s also a 1x11-specific hydraulic disc brake lever with no shifter internals, as well as a Di2 left-hand shift in which the three buttons (two on the lever, one on the hood) can be used to operated accessories like a computer or lights.
If you want more braking power, the top-end RX815 brake lever utilises the company’s Servo Wave technology from its mountain bike brakes which it claims provides a stronger braking feel with more modulation.
The regular RX180, RX600 and RX400 brake levers are closely comparable to Ultegra, 105 and Tiagra hydraulic disc brakes.
GRX STI shift/brake lever weights: ST-RX815-L/R Di2: 565g, ST-RX810-LA Left side dropper post lever: TBDg, ST-RX600-L/R: 611g, ST-RX400-L/R (10-speed): 613g
An interesting option that we’ve not seen since ye olde cyclo-cross days, and trialled by Hope a few years ago, is the new inline hydraulic sub-brake lever.
The RX812 lever attaches to the handlebar tops alongside the stem and connects to the front and/or rear brake caliper and basically gives you the option of braking when riding on the tops.
We can certainly see many situations when this would be useful to have, and chuck in the Di2 satellite shifter buttons and you could change gear and brake while on the tops.
Cyclocrossers and cobbled classic racers will also potentially find this an interesting option to have, so we expect to see it popping up a lot over the near year or two.
GRX hydraulic disc sub-brake lever weight
The flat mount brake calipers use the same design as the current road calipers but are stickered with GRX logos.
GRX calipers weights:
Rounding out the new GRX range are two sets of wheels with a choice of 700c and 650b sizes.
Both wheels are designed for the rigours of gravel riding with a wide 21.6mm internal rim width, a 22mm deep rim and 12mm thru-axle hubs.
GRX wheelset weights:
Prices haven't been confirmed yet but we'll update this article as soon as we get them.
We’re impressed with what Shimano has delivered. It’s been a long time coming but Shimano has finally entered the growing gravel and adventure market with a well-considered range of options that should keep even the most demanding gravel cyclist happy.
The range of options would appear to be ideal for those speccing their own gravel and adventure bikes, as well as giving bike brands plenty of options when it comes to building new bikes for the 2020 and beyond model years. The decision to offer three ranges with 11- and 10-speed will ensure it’s an accessible proposition too.
And finally it means sensible gearing for Shimano-equipped bikes, so hopefully no more compact 50/34t chainsets on gravel and adventure bikes.
We’ve not seen it in the flesh, or should that be forged metal, yet, but hopefully we can get a closer look at it soon and maybe even get a groupset to put it through its paces. But which configuration to go for?
If you like what you see and want to get your hands on GRX, you’ll have to wait until June for mechanical and August for Di2. More at www.shimano.com
David has worked on the road.cc tech team since July 2012. Previously he was editor of Bikemagic.com and before that staff writer at RCUK. He's a seasoned cyclist of all disciplines, from road to mountain biking, touring to cyclo-cross, he only wishes he had time to ride them all. He's mildly competitive, though he'll never admit it, and is a frequent road racer but is too lazy to do really well. He currently resides in the Cotswolds.