Shimano introduced their first “gravel specific” gruppo in 2019, so some of this is not new news.  This being said, we wanted to get a little time with the new Shimano GRX 800 components before providing an overview.

The “gravel group” parts from Shimano are designated GRX and are available in three levels – 400, 600 and 800.   400 is a 10 speed group that is comparable to the Tiagra level of road components.  600 is parallel to 105 and 800 to Ultegra.

Ultegra is the “sweet spot” for many on the road, thus we expect Shimano GRX800 to be the most popular level of GRX for our clients.  Shimano GRX800 is available in electronic Di2 shift version and mechanical shift and 1x and 2x formats.  It is of note that GRX800 1x is Shimano’s first foray into a 1x system designed for a road oriented bike.  It will be interesting to see where Shimano takes this in the future.

Without further ado, here are some of the highlights and notes on the intriguing GRX 800 groups from Shimano.

Shimano GRX 12 Speed?

Prior to release, it was anticipated that Shimano’s new GRX group was to be their first foray into 12 speed on a road bike.  Shimano kicked that can down the road though.  While this may have come at the expense of a 10 tooth cog (see below), it is hard to fault how well most of Shimano’s 11 speed systems currently perform from a mechanical perspective.  Staying with 11 speed also offers more potential for GRX to be used with some components from other Shimano road groups (Ultegra in particular…).

Shimano GRX 2x Gearing Options

Shimano offers GRX 2x in both Di2 (GRX815) and mechanical (GRX810) shift options. Out of the box, GRX 2x  gearing is 48/31 up-front mated with an 11-34 cassette. GRX810 2x cranks provide three teeth lower in the front than Ultegra compact (31 instead of 34 teeth).   GRX is almost 2.5 gear inches lower than Ultegra.

We welcome Shimano to the sub-compact offerings on the market.

Shimano GRX 1x Gearing Options

Shimano GRX 817 Di2 and GRX 812 mechanical shift are the 1x offerings.  They offer a 40T or 42T chainring that can be mated with a 11-40 or 11-42 in the back.

So, with the 40 tooth, they provide slightly lower gear possibility as Ultegra 1:1 ratio.  However, you have to give up at least 8 teeth on the high end for the simplicity of the 1x.  This will work for some, but be too much of a compromise for others.

“Hybrid” Gearing Options

It is worth noting that, while Shimano does not endorse it, we have evidence that SRAM XD 11 speed cassettes with 10 teeth play pretty well with GRX in many cases.  This allows a 40 tooth front chainring to be mated to a 10-42 cassette in order to get below 1:1 with a 1x GRX drivetrain while gaining back some of the lost high gearing.  SRAM AXS 1x with an Eagle 10-50 cassette is still the king of being able to go as low as possible with 1x.  However, the jumps in the 10-50 are greater than some like; a modified Shimano system potentially fills this gap nicely.

Likewise, depending on the frame the components are installed, Shimano rear derailleurs frequently can accept cassettes that are two teeth bigger than the max capacity listing without much protest on many bikes.  This would mean that on GRX 2x, a 46/31 can be paired with a 11-36 on many bikes, providing a low gear of 31-36.  If you switch to the GRX600 crank, you can even get a 46/30 up front for the small chainring.   It is worth noting that SRAM has some new 2x gearing options coming out very soon that should prove very strong competition for Shimano.

While GRX out of the box offers gearing that is definitely lower than Ultegra, pushing the system a bit with some retrofitting is where the opportunity lies for many in search of that “ultimate” gravel road gearing range.

It seems that the golden age of gearing options has arrived, even if the golden age of compatibility has not.  Shimano and SRAM are leapfrogging each other with options that meet just about everyone’s desires and needs.

GRX Front Derailleur Compatibility

Shimano GRX cranks kick the chainline out 2.5mm compared to their road groups.  This increases tire clearance.  It is recommended that GRX cranks be used with GRX front derailleurs that are designed to work best with the wider chainline.

While SRAM and others have closed the gap a little in recent years, the Shimano’s 2x front shifting quality remains the benchmark.

Subcompact Crank Option for the Pavement Rider?

While GRX is designed as Shimano’s gravel group, the RX810 crankset with 48/31 gearing works well for many pavement riders as well.  If you have wanted lower gearing than what your 105, Ultegra and Dura Ace group offers, a GRX crank and front derailleur could be just the ticket.

We expect the new RX810 crankset to sell really well for us as an aftermarket upgrade/change for riders pursuing lower gearing.   As mentioned earlier, the 105 level RX600 crank takes this concept 1 tooth further by offering a 46/30.

Shimano GRX Crank Length Options

As of spring 2020, Shimano is offering GRX810 cranks in 170, 172.5 and 175mm.   The lack of a 165mm is a large hole in the offerings.  Thankfully, the GRX600 crank with 46/30 gearing is available in a 165mm and is cross compatible, albeit at the expense of about 100 grams of weight.  Hopefully Shimano will expand crank length offerings in the 800 level over time.

GRX Shift Levers Ergonomics

Others have stated it – the new GRX hoods have a nice feel.  Many will prefer it to other Shimano road levers they have used in the past.  The ergonomics are good enough that we have encouraged some manufacturers to consider pairing the new GRX lever with their Ultegra road offerings too.  This would help them reduce the number of shifters they need to stock while potentially offering a lever feel that many will prefer to the current Ultegra lever.

It is worthy of note that the mechanical shift RX810 shifter and the Di2 electronic shift RX815 have a significantly different shape and feel to them.  The mechanical shift lever has more rounded lines and a longer reach to the lever while the Di2 version is more compact with a convex lower and more angular feel.

The Di2 RX815 levers also use a higher brake lever pivot location (18mm higher) to increase leverage.  The higher brake lever mount is not found on the mechanical RX810 levers.

While many media sources have reported that GRX levers are the first drop bar levers Shimano has produced with ServoWave, this is not the case.   All of Shimano’s prior hydraulic drop bar based shifters list ServoWave as a feature.

Clutch Equipped Rear Derailleurs

Up until GRX, the only Shimano rear road derailleur to have a clutch was the late edition Ultegra RX.  Shimano continues to recognize that chain slap can be an issue when riding rough roads as well as trails.  GRX 800 rear derailleurs includes a switchable clutch.

In-Line Brake Lever Option

Shimano is making a GRX in-line bar top “CX” brake lever (GRX BL-RX812) that can be added to GRX shift levers for those desiring bar top hydraulic brake levers. While we don’t expect to install a lot of them, these levers do have their place and are a nice option.

 

Dropper Post Lever & Other Shifter Options

The GRX 800 1x shifter set has an option to actuate a dropper post from the left shift lever.  For hardcore off-road gravel riders (or those just looking to make it easier to get their bike in their car…), this is a nice option.  This feature is compatible with cable actuated droppers where the head of the cable is located at the shift lever.  STI levers that offer this feature are designated “LA” (RX-810-LA).

It is worth noting that another option with the Di2 levers set-up 1x, is to reprogram the left levers to shift the rear derailleur one way and the right levers to shift it the other (a la SRAM eTap).  On a 1x, this puts the otherwise useless left Di2 lever to good use and makes shifting with heavy gloves more accurate.

Shimano GRX 800 Impressions

From our perspective, the three biggest stories regarding Shimano GRX are as follows:

1. Lower Gearing Options. We are really glad to see Shimano continue to expand their lower gearing options for drop bar bikes.  While living in a hilly area may skew our perspective on gearing, people are still asking for lower gearing options.  Albeit with a new front derailleur in some cases, the fact that GRX cranks will work with Shimano’s pavement groups is a big benefit.  It is nice to see Shimano provide some additional gears; we hope they will continue to expand that.
2. New Lever Architecture. The new GRX levers are ergonomically different from Shimano’s other road levers.  We are not going to be surprised to see some of the new ergonomics trickle over to the next generation pavement groups.  Again, like the crank, it is nice to see some cross-compatibility between GRX and road.
3. 1x.  We’ll see where this leads, but Shimano is now building a 1x road group.

 

The surprise with GRX is the lack of a 12 speed option – especially on the 1x.  On 2x, the gearing range of a 46/30 with a 10-36 would have made Shimano the clear leader in the gearing department.  This being said, it is great to see that many GRX parts will work with existing Shimano 11 speed road groups.

On the groups we’ve been able to build to date, GRX maintains Shimano’s hard-to-fault smooth and precise shifting.  The gearing options are the broadest Shimano has offered on a road group to-date and the new lever ergonomics are some of the best available.  GRX takes everything that Ultegra offers and increases the range of climbing gears.  We expect Shimano GRX 800 to be a very popular spec on many gravel (and pavement) bikes moving forward.

Contact us to learn more about upgrading the gruppo on your bike or getting a new bike using the proven “Rider First” approach that we helped pioneer.