Shimano’s new GRX RX820 adds a long-anticipated 12th cassette sprocket to the brand’s top-tier gravel groupset.
GRX remains mechanical for now, but the 12th sprocket and extended gear range bring it closer to SRAM and Campagnolo’s gravel groupsets.
But it’s the weight we’re focusing on here – what will be the effect of an extra cassette sprocket and larger cogs on Shimano GRX RX820?
Before Liam Cahill reviewed the Shimano GRX820 Unstoppable groupset, we put everything on the scales to find out what each component actually weighs.
New Shimano GRX RX820 and RX610: a primer
- No Di2 (for now) and no mechanical disc brakes
- Single and double chainring options
- Unbeatable, Undroppable and Unstoppable are the three new GRX configurations
- 10t smallest cog on 1x groupset
- Choice of 10-45t and 10-51t 1x cassettes
- RX22-GS and SGS derailleur cages are interchangeable
- Second-level GRX RX610 moves to 12-speed in 1x and 2x set-ups
Shimano GRX RX820 groupset component real weights
Shimano GRX ST-RX820 shifters weight
Shimano claims the ergonomics of the new GRX brake lever and bracket are “gravel-specific” and designed to be used with flared gravel handlebars.
The anti-slip coating on the brake lever is borrowed from Shimano’s fishing rods. This aids grip in wet weather, according to the brand.
We weighed a pair of the 1x12 ST levers at 530g – the left contributing 298g and the right 232g.
- Claimed weight: 511g
- Actual weight: 530g
Shimano GRX RX820-1 crankset
On our scales, the single ring, 40T Shimano GRX810 RX820-1 crankset weighs 646g. Our sample has 172.5mm cranks. 170mm and 175mm lengths are also available.
In a 1x drivetrain guise, you can also choose a 42T chainring. The sole 2x drivetrain (Shimano GRX810 RX820-2 crankset) configuration is 48/31T.
Both cranksets incorporate Shimano’s Hollowtech II technology.
- Claimed weight: 655g
- Actual weight: 646g
Shimano GRX RX822-SGS rear derailleur
Shimano GRX820 has two types of rear derailleur for its 1x drivetrains and one for the 2x option.
The long-cage Shimano GRX RD-RX822-SGS rear derailleur has the capacity for a 10-51t cassette.
The medium-cage Shimano GRX RX822-GS rear derailleur has a maximum sprocket size of 45t.
Both the 2x cassette sizes (11-34t and 11-36t) work with the RX820 rear derailleur. The largest sprocket it can accommodate is 36t.
We weighed the long-cage rear derailleur (RD-RX822-SGS) at 295g.
- Claimed weight: 288g
- Actual weight: 295g
Shimano CS-M8100-12 cassette
The Shimano CS-M8100-12 cassette intended for the GRX 1x drivetrains comes in two sizes: 10-45t and 10-51t.
Both have Micro Spline freehubs to accommodate that 10t sprocket. By contrast, the 11-34t and 11-36t cassettes are compatible with HG and HG+ freehubs.
Shimano calls the pairing of the mountain bike-style 10-51t cassette and RX822-GS rear derailleur GRX RX820 Unstoppable. This is the brand’s first mullet drivetrain for gravel riding.
The toothiest 10-51t cassette tips our scales at 473g and the 10-45t size is claimed to weigh 461g.
- Claimed weight: 470g
- Actual weight: 473g
Shimano BR-RX820 brake caliper and hose
Shimano has updated the GRX BR-RX820 brake caliper with its freshest hydraulic caliper technology.
The bleed port moves to the outward-facing side of the caliper to be easier to access. You can now open it with an Allen key instead of a spanner.
Shimano has also introduced Servo Wave technology and increased pad clearance by 10 per cent in a bid to quieten disc brake noise.
We weighed the front BR-RX820 brake caliper and hose together at 156g. Shimano says the front caliper weighs 146g on its own.
- Claimed weight: 146g (caliper only)
- Actual weight: 156g (caliper and brake hose)
Shimano RT-CL800 160mm rotors
Shimano GRX820 uses RT-CL800 disc brake rotors, which were first unveiled when the Shimano 105 Di2 R710 groupset was launched. These, in a road context, are Ultegra-level.
The rotors have a heavier aluminium carrier which is claimed to stop them from deforming when they heat up.
The 160mm RT-CL800 rotor weighs 109g on our scales, which is 5g lighter than the claimed weight.
- Claimed weight: 114g
- Actual weight: 109g
Shimano CN-M8100 chain
Shimano has stuck with the 12-speed CN-M8100 chain originally developed for its mountain bike groupsets but is also used for its Ultegra Di2 R8100 road groupset.
As seen originally on the Shimano Deore XT M8100 groupset, the extended link plate is claimed to enhance the chain’s engagement and retention.
- Claimed weight: 252g
- Actual weight: 247g
Shimano GRX RX820 groupset total weight
All in, the £1,349.92/$1,542.92 Shimano GRX RX820 Unstoppable groupset weighs 2,822g (excluding bottom bracket).
From SRAM, there’s no 12-speed, mechanical option equivalent. Force is 12-speed but electronic-only.
The closest competitor is SRAM Apex Eagle, which weighs a claimed 3,148g and costs £1,071/$1,020.
