Shimano has today announced a whole range of gravel components under its new GRX name.
Sitting alongside its existing road groupsets, GRX adds new hydraulic disc STI levers, cyclocross-style in-line levers, clutch-equipped derailleurs and cranks, including — for the very first time from Shimano — dedicated 1x components for drop-bar bikes. There’s also a new ‘gravel-tuned’ wheelset available in both 650b and 700c versions.
Shimano is keen for a slice of the gravel, adventure and bikepacking segmentShimano
Shimano GRX: Three levels of gravel goodness
GRX components will be available at Ultegra Di2, Ultegra, 105 and Tiagra levels, but there aren’t groupset-specific versions of every component. The corresponding product code for each groupset is as follows:
Ultegra: RX800 (Ultegra mechanical shifters are ST-RX810, Ultegra Di2 shifters are ST-RX815)
RX400 components are 10-speed, while the rest are 11-speed (except for the 2×10 RX600 cranks) to fit in with the existing groupset hierarchy.
Curiously, while 11-speed riders will have the choice of 1x or 2x cranks, the 10-speed cranks are 2x-only, although doubtless some riders will throw caution to the wind and mix and match components.
RX800 Di2 offers two derailleur options and both 1x and 2x cranksShimano
The mechanical 11-speed option gives you similar choicesShimano
10-speed GRX is designed to be 2x-onlyShimano
Shimano GRX STI levers: new shape, Servo Wave, dropper control
The GRX range includes levers restyled for off-road ridingShimano
The GRX range includes completely new mechanical and Di2 levers with a profile that’s said to be sculpted for off-tarmac comfort. The brake lever’s pivot point has moved upwards by 18mm, creating a more pronounced hood hump, which should make sitting on the hoods more secure on rough terrain. The levers themselves have more of a curve against which to hook your fingers, and both hood and levers have a textured finish for grip.
GRX Di2 levers (RX815) will also benefit from Servo Wave, a design borrowed from the company’s MTB brakes. Servo Wave makes the relationship between lever and brake pad movement non-linear.
In the first part of the lever stroke, the pads move together quickly to meet the rotor. Part way through the stroke, the rate of closure slows, trading speed for power and modulation.
As a bonus, Shimano says that riders running 1x GRX mechanical setups will be able to use the left shifter to control a dropper post. For riders who want 1x only with no dropper, a brake-only lever with no shifting internals will be available.
Shimano GRX levers claimed weights
RX815 Di2 levers (pair): 565g
RX600 levers (pair): 611g
RX400 levers (pair): 613g
Shimano GRX ‘sub brake levers’
We reckon Shimano is the first to bring a hydraulic inline brake lever to marketShimano
GRX offers cyclocross-style in-line hydraulic levers — Shimano calls them ‘sub brake levers’ — which mount on the bar tops and get the product code BL-RX812L/R.
In-line hydraulics require some clever engineeringShimano
We don’t yet have precise details of how the new GRX ’cross levers work nor claimed weights, but we’re intrigued to find out more.
Shimano GRX brakes
The branding is new, but the GRX disc calipers look just like existing road onesShimano
GRX disc brake calipers come in RX800 and RX400 flavours and are, branding aside, virtually identical to Shimano’s current road calipers. They’re fitted with Ice Tech finned brake pads as standard and use the now nearly-universal flat mount standard.
Shimano GRX brakes claimed weight
RX400 (per caliper): 143g
Shimano GRX rear derailleurs
The Ultegra-equivalent RX810 takes over from the existing Ultegra RX derailleurShimano
The Di2 option isn’t significantly chunkier than its mechanical counterpartShimano
Building on the existing Ultegra RX option, GRX rear derailleurs make use of the same Shadow RD+ design borrowed from mountain bikes, which entails a switchable “chain stabilizer system”, i.e. a clutch to keep your chain in check over rough ground.
The new line-up includes mechanical RX400 and RX800 options, plus RX800 Di2 versions.
The Tiagra-level 10-speed RX400 rear derailleur is intended for cassettes ranging from 11-30t to 11-36t.
The mountain bike DNA of the GRX derailleurs is obvious. This is the 10-speed RX400 optionShimano
For 11-speed, riders running 11-30t or 11-34t cassettes should choose the RX810/815 (mechanical/Di2) option, while those running 11-40t or 11-42t cassettes will need the longer cage RX812/817 (mechanical/Di2) version.
Shimano GRX rear derailleur claimed weights
RX815 Di2: 288g
RX817 longer cage Di2: 322g
RX812 longer cage: 264g
Shimano GRX front derailleurs
GRX front derailleurs are designed for a chainline that’s 2.5mm wider than that of the road groupsetsShimano
It might not seem very edgy to keep making front derailleurs, but it’s safe to say they aren’t going anywhere for a while. Shimano is offering three options for GRX: RX400, RX810 and RX815 (Di2).
The design isn’t radically different to existing products but, critically, the chainline has been shifted outwards by 2.5mm to increase tyre clearance and be better optimised for wider rear spacing. The mechanical derailleurs share the same compact design that’s been steadily trickling down since the launch of Dura-Ace R9100.
Officially, the front derailleurs will clear 42mm-wide tyres and we’re assuming that’s for 700c rubber — wider should be feasible with 650b.
Shimano GRX front derailleur claimed weights
RX815 Di2: 131g
Shimano GRX cranksets
Shimano has finally, FINALLY made a dedicated 1x crank for drop bar bikesShimano
GRX cranks use a four-arm spider to match existing options. 1×11 riders will have the choice of 40t (RX800/RX600 level) or 42t (RX800 only) cranks. The 1x options make use of Shimano’s Dynamic Chain Engagement tooth profile, which has been used on the brand’s MTB groupsets for at least the last five years to provide better chain retention over rough ground.
The 2×11 RX810 crank is a 48/31t, which Shimano notes has the widest range it has ever offered in a double crankset.
Shimano isn’t going to stop making 2x cranks any time soonShimano
The RX600 crank is 46/30t and comes in both 10 and 11-speed versions. Shimano nerds may raise an eyebrow at a nominally 105-level crank being 10-speed, but there you have it.
To match the front derailleurs, GRX cranks share that 2.5mm wider chainline, meaning they likely won’t work optimally with existing setups if you were thinking of retro-fitting parts.
Shimano GRX cranks claimed weights
RX810 1×11: 655g
RX600 1×11: 753g
RX810 2×11: 722g
RX600 2×11: 816g
RX600 2×10: 819g
Shimano gravel-tuned WH-RX570 wheels
The RX570 wheels aren’t exactly groundbreaking, but they look to offer a useful all-round specShimano
Alongside the groupset components, Shimano is launching a ‘gravel-tuned’ alloy wheelset called the WH-RX570. This will be available in both 650b (non-boost) and 700c versions weighing a claimed 1,600g and 1,650g respectively.
These will be tubeless-only, featuring a rim that measures a healthy (if not radical) 21.6mm internally and which is 22mm deep.
Shimano GRX compatibility
GRX components are designed to work with existing Shimano components, so as long as you stick to the same number of gears (11 with 11, 10 with 10), you have the choice of any of Shimano’s current cassettes and chains.
The 2.5mm wider chainline means that you’ll be best off matching GRX cranks to GRX front derailleurs.
Shimano GRX pricing and availability
Pricing on all components is to be confirmed, but we’re confident that it will be within shouting distance of the equivalent components at a given groupset level.
Full availability is also to be confirmed, but we’re told that mechanical 1×11 and 2×11 components will be available from June, while 1×11 and 2×11 Di2 will arrive in August. The sub-brake levers and dropper compatible shifter will emerge around September.
In any case, we’re expecting to see GRX on some 2020 model year bikes.
Shimano GRX — BikeRadar’s take
GRX will be welcome news to Shimano fans who’ve yearned for an offical 1x option for drop barsShimano
GRX has been a long time coming. Shimano isn’t really known for its risk-taking, preferring to let a market segment develop and evolve before diving in.
SRAM has been making 1x groupsets for drop-bar bikes for around four years and, in the meantime, gravel riders who preferred Shimano had to make do with mix-and-match setups.
As an announcement, it may lack the pizazz of SRAM’s Force AXS launch, but GRX is a very logical step that will delight Shimano fans as well as bike brands looking to spec Shimano-only gravel and adventure bikes.
We’re looking forward to seeing the new components on next year’s bikes and we’ll bring you more as soon as we can lay hands on them.
Matthew Loveridge (formerly Allen) is an experienced mechanic and an expert on bike tech who appreciates practical, beautifully-engineered things. Originally a roadie, he likes bikes and kit of every stripe, and he's tested a huge variety of both over the years for BikeRadar, Cycling Plus and others. For a long time Matthew's heart belonged to the Scott Addict, but he's currently enjoying Specialized's sublime Roubaix Expert and having a torrid affair with a Giant Trance e-MTB. At 174cm tall and 53kg, he looks like he should be better at cycling than he actually is, and he's ok with that.