Product news / Gravel: Gravel bikes have long since outgrown their former niche and with their increasing popularity, the need for components specially tailored to the universal racers is also increasing. Shimano's answer to this is GRX - a complete series of special Gravel components that break new ground in several respects. We have all the information about the new Shimano GRX.
Shimano GRX Gravel group: RX 800, RX 600 and RX 400
With the new Shimano GRX, the Japanese are breaking new ground. This not only affects the group itself and its orientation, but also its location in the Shimano cosmos; like the gravel sector itself, the GRX cannot be clearly assigned to the road or MTB sector and therefore occupies a certain hybrid position between the two established categories in the Shimano product portfolio.
Similar to Dura Ace, Ultegra and 105 or XTR, XT and SLX, there are also quality and price gradations within the GRX products. Specifically, this means: The top group gets the abbreviation RX800, is both as mechanical as well as Di2 variant available, switches over at the rear eleven sprockets and at the front optionally with one or two chainrings. The middle class listens to the name RX600, Likewise 11-fold, a few grams heavier and also with one or two chainrings. The entry-level components from the RX400 Group are for one only 2×10 translation designed. In order to make the subdivision more user-friendly and variable, all components are compatible with each other - provided the number of gears and the type of gearshift (mechanical / Di2) match.
Mix and Match: High variability within the GRX groups
The special Gravel path that has been taken also continues in the selection of components within the individual subgroups: All individual components are only available in the top group, while the RX600 does not have its own rear derailleur, but instead has an 11-speed crankset 10-fold variant for the RX400 components. At first glance, this division seems confusing – for us too. Therefore, you will find a graphic below that lists the respective possible combinations.
Also interesting for owners of current road bike groupsets: The 11-speed GRX STIs are compatible with current 11-speed road derailleurs. It should be noted, however, that with the exception of Ultegra RX no Shimano road bike rear derailleur is equipped with Shadow+ damping. Conversely, this also means that existing 11-speed Road STIs can be ridden with the new GRX rear derailleurs. For many, for example, a cheap way to convert the existing 2×11 road drive on a crosser or gravel bike to a 1×11 with a wide range of cassettes.
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Shimano GRX Gravel group: rear derailleurs compatible with road bike and MTB cassettes
The obvious special position of the Shimano Gravel group also becomes clear when using the cassettes. Instead of own chains and cassettes, the well-known components from the racing bike and MTB sector are used. Both are compatible Road (11-30 / 11-32 / 11-34) as well as most MTB Cassettes (11-40 / 11-42). The RX800 rear derailleur is available with a long (RX812 / RX817) and short cage (RX810 / RX815). The long version should be used by those who want to drive a 1-speed drivetrain with a wide MTB cassette. Conversely, the short version is interesting for everyone who is using a front derailleur. The RX400 10-speed rear derailleur can be ridden with two chainrings and either 11-32, 11-34 or 11-36 at the rear.
All rear derailleurs have in common the ones known from the MTB sector Shadow+ rear derailleur damping. This ensures a higher chain tension and thus significantly reduced chain slap in the field. This is particularly important if you are only on the move with one blade, as otherwise there is a risk of chain drops.
Shimano GRX Gravel group: cranks with one or two chainrings and large gear steps
As known from the Japanese, all cranks are made of aluminum and use the well-known Hollowtech 2 bottom bracket standard. Both the RX800 and RX600 cranks are available with one or two chainrings. If you rely on a 1-speed drive, you can choose between a 800 or 40 tooth blade for the RX42 crank, the slightly cheaper RX600 only comes with 40 teeth. The dual variants of both cranks are exciting: with one 48-31 gradation Shimano relies on a completely new chainring combination on the RX810-2 - the jump of 17(!) teeth is the largest that Shimano has ever had. The 2x version of the RX600 crank has a slightly smaller gear jump from 46 to 30.
Transmission bandwidths Shimano GRX:
RX810 2x with 11-34 cassette: 479%
RX810 1x with 11-42 cassette: 382%
RX600 2x with 11-34 cassette: 474%
RX600 2x with 11-36 10x: 502%
A special feature of the GRX cranks is the chain line, which is further out than the previously known racing bike cranks. Shimano tries to create more space for large-volume Gravel tires in the very narrow bottom bracket area when using a front derailleur. However, this also means that the GRX 2-speed cranks will only be compatible with the GRX front derailleurs.
Shimano GRX Gravel group: STIs only for hydraulic disc brakes and with special Gravel ergonomics
Now we come to the STI shift brake levers. There is even more choice here than with the other components. For the sake of simplicity, let's start with the similarities: All GRX are STIs exclusively for hydraulic disc brakes designed. Rim brake fans are looking into the tube - although the proportion of rim brake riders in the gravel area is likely to be negligible anyway.
Otherwise, there are the right controls on the cockpit for every conceivable combination: In addition to the RX815 Di2 STIs, the mechanical 11-way levers are available in both the RX800 and the RX600 series. If you can do without a front derailleur, you can left a brake lever without any shift mechanism drive. Those who are also on a gravel bike with a dropper post will also find a left brake lever, with which mechanically controlled dropper posts can be operated. This should be compatible with most dropper posts - the only requirement: the cable must be clamped to the post because its head is in the lever. This special dropper post STI is only available for the mechanical groupsets and at RX800 and RX600 level.
The RX815 Di2 variant continued to be Ergonomically completely redesigned. The grip area is a little higher to provide more security off-road, and the axis of the brake lever itself moves up a bit and thus generates greater braking power. The Hood and brake lever surface are knurled, so that you always have a firm grip even in the heat of the gravel battle. The other STIs also have the textured surfaces, but are otherwise ergonomically based on the well-known Hydro-STIs from Shimano.
Shimano GRX Gravel Group: Two brake calipers and innovative additional levers for the upper link
Two GRX calipers will also be available to match the Hydro-STIs. The RX800 saddle is intended for the RX600 and RX810 groupset, the 10-speed RX400 group gets its own brake. Both are optically and technically strongly based on the well-known road brake calipers from Shimano, only available with Flatmount mounting and also bring the proven ICE technology including its cooling fins.
Additional brake lever for the upper link one or the other may know it from the past, but with the RX812 levers, Shimano is bringing this idea into 2019. The two compact brake sensors are clamped right next to the stem and, so to speak, "interposed" on the brake line. So anyone who likes to grip the top link a lot will find the right brake levers.
Shimano GRX Gravel group: wheels for 700c and 650b
Matching wheels will also be available to round off the Shimano Gravel group. These listen to the name RX570 and will both as a classic 700c and for the smaller 650b tires may be available. The rims have one inner width of 21.6mm and are of course tubeless-ready. Thanks to the compact rim height of 22mm, the weight can be kept low and comes to 1600g (700c) or 1540g (650b). The Shimano Gravel wheels are exclusively with 12mm thru-axle in front and 142x12mm in the back .
Shimano GRX Gravel group: weights and availability
Unfortunately, the GRX groupsets will only be available later this summer. Shimano plans to launch the mechanical groupset in July, followed by the Di2 variants in August. The additional brake levers and the brake lever for dropper posts are not expected until September.
Already known weights of the individual components:
Component | designation | Weight |
---|---|---|
Crank | FC-RX810-1 | 655g |
Crank | FC-RX600-1 | 753g |
Crank | FC-RX810-2 | 722g |
Crank | FC-RX600-11 | 816g |
Crank | FC-RX600-10 | 819g |
Front derailleur | FD-RX815-F | 131g |
Front derailleur | FD-RX810-F | 94g |
Front derailleur | FD-RX400 | 95g |
derailleur | RD-RX815 | 288g |
derailleur | RD-RX817 | 322g |
derailleur | RD-RX810 | 251g |
derailleur | RD-RX812 | 264g |
STI | ST-RX815 | 565g |
STI | ST-RX600 | 611g |
STI | ST-RX400 | 613g |
caliper | BR-RX400 | 143g |
wheelset | WH-RX570 700c | 1600g |
wheelset | WH-RX570 650b | 1540g |
Luke Grundner says
Hallo,
They write that "the GRX 2-speed cranks will only be compatible with the GRX front derailleurs."
But what about the compatibility between GRX front derailleurs and Shimano 105 STI?
I would like to equip an existing Shimano 105 R7020 with a GRX crank 48/31 or 46/30. Is replacing the crank and front derailleur enough here?
Thank you!
Lukas
Michael Faiss says
Hi Luke,
Good question - I think that the components are compatible, but just to be on the safe side I checked with the German Shimano sales department. I'll add the answer here as soon as I have it!
Regards
Michael
Michael Faiss says
Hi Luke,
I now have the answer directly from Shimano. The GRX derailleurs are compatible with all current Road STIs. So nothing stands in the way of your project.
Here you can find the entire compatibility list again in black and white:
https://productinfo.shimano.com/#/com?cid=C-453&acid=C-455
Regards
Lukas says
Hi Michael!
Cool overview - perfect!
Thank you for your quick and precise answer.
lg
lg
Andy Wheels says
I bought the complete 800 group. Now I have the problem that my frame only has a post mount for a 160mm disc at the back.
Is there an adapter for the GRX saddle on a post mount, or can I install an XT post mount saddle instead and do the brake lines of the GRX STIs fit?
Norbert Walter says
Can the GRX RX 810-2 be combined with the long cage (RX 817?) and an XT cassette with 11 – 42 teeth?
Harold Kirchtag says
that's exactly what interests me as well. I often travel with luggage and I want it to be easier up the mountain.
Norbert Walter says
I'm over 70 and travel a lot in the mountains and would like to make it a little easier for me.