Shimano GRX groupsets - An overview of all Shimano Gravel bike groupsets

Gravel bikes are blowing up right now! You can't go on a forest ride without seeing one. And with more and more bike brands jumping on the bandwagon, there are a ton of options out there. So, how do you know which one is good? Well, one key factor is the groupset. And when it comes to gravel bikes, Shimano GRX is a solid choice. That's why we sorted through all the Shimano GRX groupsets for you, so you can find the perfect one for your gravel bike!

What is GRX?

Shimano GRX is a groupset designed specifically for gravel bikes. Gravel bikes includes everyhting from bikepackers to cyclocrossers. Shimano GRX groupsets offer a wide range of possible fittings, including 10-speed, 11-speed, single and double drivetrains. Within the Shimano GRX range you can also choose between electronic and mechanical shifting.

Moreover, Shimano also offers the GRX group with dropper post integration, giving you the option to fit a dropper post.

Shimano did not have to create a completely new groupset. The Shimano GRX groupset is in many ways derived from existing techniques used in both road and mountain bike groupsets, with the addition of some new components. Nevertheless, according to Shimano, it is "the world's first dedicated gravel groupset".

A short overview of the current Shimano GRX groupsets

Shimano categorises GRX into 3 different groupsets, namely:

GRX 800 The Shimano GRX 800 is the best gravel bike groupset currently available. This groupset is comparable to the Shimano Ultegra road groupset. It is an 11-speed groupset available with mechanical or electronic (di2) shifting.

GRX 600 The GRX 600 is Shimano's mid-range gravel bike groupset. This groupset is comparable to the Shimano 105 road groupset. It is an 11-speed group (an optional 10-speed crank is also available). As with the 105 groupset, you can only opt for mechanical shifting.

GRX 400 The Shimano GRX 400 groupset is an ideal groupset for beginners in gravel cycling. This groupset can be compared to the Shimano Tiagra groupset for road bikes. Compared to the other GRX groupsets, the GRX 400 is a 10-speed groupset. The shifting is mechanical like the GRX 600.

No uniform hierarchy in group sets: mix and match

Things are complicated by the fact that, as already mentioned, Shimano has not decided to create a full-fledged group for each series. Take the RX600 groupset, for example. You cannot create a complete GRX600 groupset from this series because Shimano decided not to make a GRX600 rear derailleur. This is why you will never find a gravel bike groupset with a complete GRX600 groupset.

This means that if you fancy a mechanical 11-speed rear derailleur, you should go for the RX800. Why Shimano chooses not to go for a full group as they do for their road groups is not entirely clear to us, but practically at least it means you will sometimes have to mix and match to get a complete set.

A detailed overview of the Shimano GRX groupsets, broken down by component

The GRX cranksets

There are three types of cranksets to choose from:

• • 1 x 11-speed
  • 2 x 11-speed
  • 2 x 10-speed (Unfortunately, there is no 1 x 10-speed crankset)

The GRX single chainring cranksets use Shimano's Dynamic Chain tooth profile. The cranks have longer teeth that are alternately wider and narrower. This design prevents the chain from flying off in rough terrain.

It is also important to note that each GRX crankset has a chainline that is 2.5mm further out than a standard road crankset. This is because the wider tyres found on a gravel bike require extra space in the frame. Among other things, the width of the rear fork has to be adjusted accordingly. The 2.5mm offset then compensates for this difference.

Gearing

The GRX 800 series is available as a double crankset with a 48-tooth outer chainring and a 31-tooth inner chainring or as a single chainring crankset with a 42-tooth chainring or a 40-tooth chainring. The GRX 600 series is available as a double crankset with a 46-tooth chainring and a 30-tooth chainring or as a single chainring crankset with a 40-tooth chainring.

As already mentioned, not all the series are available in their entirety, so the GRX 400 series, for example, does not have a separate crankset. You are therefore forced to choose between a GRX 600 or GRX 800 crankset with double chainrings. The main difference between the 600 and 800 series is that the 800 crankset uses Shimano's Hollowtech technology, which makes it 100 grams lighter.

Een overzicht van de verschillende crankstellen:

Model	single/double	10/11-spd	weight
FC-RX810-1	1x	11-spd	644 g
FC-RX810-2	2x	11-spd	710 g
FC-RX600-1	1x	11-spd	743 g
FC-RX600-11	2x	11-spd	806 g
FC-RX600-10	2x	10-spd	810 g

The GRX front derailleurs

As mentioned earlier, the GRX groupsets are available with mechanical or electronic shifting. Here, too, there is a clear difference present with the road bike group sets, namely the extra 2.5mm of 'outboard clearance' to make room for the wider tyres. This makes it necessary to use the corresponding GRX crankset with the same extra 2.5 mm, otherwise the alignment of the set will no longer match.

Both the RX810 and RX815 Di2 front derailleur have the capacity to bridge a 17-tooth difference between the 2 front chainrings. The RX400 10-speed front derailleur is limited to a maximum difference of 16 teeth.

An overview of the different front derailleurs

Model	10/11-spd	Di2/mechanical	weight
FD-RX815-F	11-spd	Di2	131 g
FD-RX810-F	11-spd	Mechanical	96 g
FD-RX400-F	10-spd	Mechanical	96 g

The GRX rear derailleurs

Like the front derailleurs, the GRX line also has several (mechanical and electronic) rear derailleurs. Regardless of which derailleur you choose, they each use Shadow RD+ technology. This is designed to stabilize the chain when cycling on uneven terrain.

This is done by minimizing unnecessary movement of the derailleur cage. The idea is that this allows for better "chain retention," the reduction of "chain-slap" (chain hitting the chainstay) and a quieter ride with even better shifting performance.

Each rear derailleur also has a stabilizer. This is an on/off switch that allows you to change the chain tension and minimizes chain bounce.

Derailleur placement

The GRX derailleurs are positioned further below the cassette than traditional road bike derailleurs. They protrude less far from the frame when using the smallest sprockets. The idea here is that this makes the derailleur less exposed and vulnerable to damage from, for example, bushes, stones or your bike falling over.

Cassettes and chains

No proprietary cassettes and chains are made for GRX. It is common to fit a cassette from the race or MTB series. For example, if you use a Shimano Ultegra or 105 11-speed cassette with 11-30/34 gearing, it is recommended to use the RD-RX815 Di2 short-cage rear derailleur or the RD-RX810 mechanical rear derailleur.

If you opt for a 10-speed system, you will need the RD-RX400 which can handle a sprocket with up to 36 teeth. This derailleur incorporates more steel and less aluminium than the RX800 rear derailleurs, hence it results in a higher weight.

If you choose XT, SLX or Deore, you can fit a cassette with a maximum of 42-tooth. However, it is important to fit the longer-cage Di2 RD-RX817 or mechanical RD-RX812 derailleur. Both derailleurs have a 'cable-pull' ratio (the size of the gear 'steps') similar to Shimano's road racing derailleurs.

Want to read more about derailleur capacity? Have a look at our blog. Find out how to calculate your derailleur capacity.

Overview of different rear derailleurs

Model	10/11-spd	Di2/mechanical	Max T	Weight
RD-RX815	11-spd	Di2	34T	288 g
RD-RX817	11-spd	Di2	42T	322 g
RD-RX810	11-spd	Mechanical	34T	255 g
RD-RX812	11-spd	Mechanical	42T	267 g
RD-RX400	10-spd	Mechanical	36T	303 g

GRX Brake levers

Specifically for the GRX, Shimano has developed STI (brake and shifting integrated) levers for both mechanical and electronic shifting. These STI levers use an ergonomic lever design specifically designed for gravel.

The focus on off-road use is also reflected in the shape of the lever hood. It is larger than normal, which is designed to provide a safer hand position on rough terrain. This improved hood helps keep your hand behind the brake lever, even with many bumps and knocks on the handlebars. A hood prevents your hand from sliding over the top of the lever, with all the consequences that entails.

Moreover there is also a deeper scoop in the centre of the brake lever, along with a non-slip textured finish that provides even better grip on the lever.

A multitude of off-road-specific options

Besides the standard STI shifters, Shimano also offers a mechanical ST-RX810-LA brake lever that, in combination with a 1x11 drivetrain, can operate a dropper seatpost. The integrated system is compatible with cable-controlled dropper posts. Note, however, that this only works with a dropper with 9 mm 'lever-throw'.

Shimano also offers 1x11 left-side hydraulic disc brake levers designed without a dropper or internal shifting elements. These are the BL-RX810 and BL-RX600 respectively. So for example, if you want a 1x system with RX600-level components, you can buy an ST-RX600-R right STI shifter and a BL-RX600-L left brake lever.

Subbrake levers: For the real gravel enthusiasts

The BL-RX812 hydraulic 'sub brake levers' are one of the most exotic additions to this gravel groupset, as far as we are concerned. These are a second set of, 'MTB-style' brake levers that you can place on the upper part of your handlebars. They connect to the brake system's hydraulic lines, providing a second braking position.

One can imagine plenty of situations where this could be useful, for example in cyclocross or the classics on cobblestones. If you then add satellite switches (Di2), you can subsequently also shift gears with your hands on the top of the handlebars.

An overview of the different GRX brake levers

Model	10/11-spd	Di2/mechanical	weight
ST-RX815	11-spd	Di2	282 g
ST-RX810	11-spd	Mechanical	284 g
ST-RX600	11-spd	Mechanical	306 g
ST-RX400	10-spd	Mechanical	306 g
ST-RX810-LA (dropper post lever)	11-spd	Mechanical	263 g
BL-RX810-L (L-side only)	11-spd	Mechanical	222 g
BL-RX600-L (L-side only)	11-spd	Mechanical	227 g
BL-RX812	11-spd	Hydraulic	82 g

Calipers

The flat-mount calipers are no different in design from current calipers, but obviously have GRX logos. They have the same features such as one-way venting and Shimano's Ice Technologies heat-dissipating fins in the pads and rotors. It results in powerful and consistent braking as we are used to from the Ultegra and 105 brakes in road bikes.

Model	10/11-spd
BR-RX810	148g/138g
BR-RX410	148g/138g

Last but not least: GRX wheels

Shimano also has two sets of tubeless-ready GRX wheels in its range. A 700C option and a 650B option. Each has a rim with an internal width of 21.6 mm and a height of 22 mm. The hubs are based on a 12 mm thru-axle.
Shimano claims the following weights per model:

• WH-RX570 700C: Front Wheel 769g, rear wheel 951g
• WH-RX570 650B: Front Wheel 737g, rear wheel 920g