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.
Last year’s launch of the MTB-style clutch-equipped Ultegra RX derailleur was a hint that Shimano might be waking up to the fact that people like riding drop-bar bikes off-road.
As it turns out, it was a teaser for so much more. Read on for full details of GRX including, where we know them, claimed weights for the new components.
- Shimano GRX — dream gravel groupset or too little, too late?
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- Shimano GRX gravel groupset review
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)
- 105: RX600
- Tiagra: RX400
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.
Shimano GRX STI levers: new shape, Servo Wave, dropper control
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 RX800 series levers (both mechanical and Di2) 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 1× GRX mechanical setups will be able to use the left shifter to control a dropper post. For riders who want 1× 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’
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.
We think these are the first production levers of this type; Hope showed off a similar setup (in conjunction with SRAM levers) back in 2016, but it was never made available to the public.
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
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
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.
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
- RX810: 251g
- RX812 longer cage: 264g
Shimano GRX front derailleurs
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
- RX810: 94g
- RX400: 95g
Shimano GRX cranksets
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 1× 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.
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
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.
11-speed GRX components are broadly compatible with 11-speed road groupsets (so you can run road shifters with GRX derailleurs, for example), but 10-speed RX400 components are officially only compatible with Tiagra 4700 components, and not other 10-speed groupsets.
GRX’s 2.5mm wider chainline means that you’ll be best off matching GRX cranks to GRX front derailleurs. For full details of what works with what, consult Shimano’s detailed compatibility charts.
Shimano GRX pricing
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 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 1× 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.