Courtesy Shimano

Can Shimano GRX Save the Touring Drivetrain?

Sep 24, 2019

There was a time, not so long ago, when mountain and road drivetrain parts from the world’s biggest manufacturer played nicely together. Road brifters had no problem shifting a mountain derailer, and flat-bar trigger shifters could pull cable on a road setup. Product managers could find a nice set of 3x9 brifters and pair them with a wide-range triple up front and any available mountain bike 9-speed cassette and bang, you’ve got a nice 20-gear–inch(-ish) low end with plenty of top-end grunt for long descents.

Those halcyon days ended in 2010 when Shimano introduced its “Dyna-Sys” 10-speed mountain bike drivetrain, which used a new pull ratio and set the brand’s road and mountain parts spinning off in different directions. This meant you were either stuck with 9-speed even as drivetrains started sprouting gears like weeds after rain (Shimano still produces the M772 XT rear derailer for this purpose), or you had to start fidgeting. Barcons are an option, as are Gevenalle shifters or thumbies. So too could you fit a Tanpan from Wolf Tooth Components, which alters the pull ratio and allows 10- and 11-speed road and mountain shifters to play nice. 

The emergence of “gravel” as a cycling category in the last few years gave product managers another tool — super-compact double cranksets like the Praxis Alba offered up 48/32T ring combos that, when paired with with a 32T or 34T cog at the top of a cassette, could begin to offer gearing appropriate for nearly any hill … so long as you weren’t carrying more than a couple of water bottles. Touring bikes continued to slog along with low-end 3x9s, with stalwarts like the Salsa Marrakesh and Trek 520 offering brifters, sure, but limited to Alivio- and Sora-level components. Burly, but not burnished.

(Despite its 1:1 pull ratio, SRAM seems generally uninterested in the traditional touring market, especially in the last few years as the brand drops front derailers entirely. Their Eagle drivetrains have revolutionized what’s possible when bikepacking, and their new wireless AXS groups offer an intriguing — but extremely expensive — mix-and-match possibility.)

Shimano GRX group's bike braking is all hydraulic
The new GRX group's braking is all hydraulic, but the drivetrain comes in 1x and 2x configurations.
Courtesy Shimano

Nearly a decade after pulling the pin on cross-compatibility, Shimano launched an entirely new category of components earlier this year called GRX. Pitched as a “Gravel/Adventure” group, it has 10- and 11-speed variants in both mechanical and electronically shifted configurations. Last month I went a few hours north to Whitefish, Montana, to ride the new group for a few days on roads and trails just off the Great Divide Mountain Bike Route and get an early sense of whether this new groupset has the potential to close the gap that Shimano opened for adventure cyclists years ago.

Full disclosure: Adventure Cyclist’s former Technical Editor Nick Legan, who went to work for Shimano around the time of GRX’s launch, extended the invite.

As mentioned, Shimano offers GRX as 10- and 11-speed cassette configurations, and it only gets more complicated from there. The 11-speed can be outfitted as a 1x or 2x with a different derailer tapped depending on the number of chainrings. And while the 1x option can handle up to a 42T cog out back, the 2x is limited to a 34T. Up front? The lower-spec RX600 series only comes in a 40T and the higher-zoot RX800 series crank can use 40T or 42T for 1x. The doubles offer a 46/30T in the 600 series or 48/31T combo on the 800. The 10-speed configuration (RX400 series) only comes in a 2x10 with a 46/30T up front and a max rear cog of 36T.

Complicating matters further is that most cyclists have become accustomed to pricing and quality generalities based on Shimano’s long-standing offerings. Is this XTR/Dura-Ace level? Too rich for my blood. Alivio/Sora? Please. Well, GRX slots in around Tiagra for the 400-level components and Ultegra for the 800-level option (the 600-level matches 105). And combined with the lowest-possible gear option of 30-36T, the 400 level potentially holds the most potential for loaded touring with a gear inch down around 22 on 700c x 32mm tires. That’s not bad, and when you consider some other perks that come with GRX, it starts to look downright interesting.

First, this is a hydraulic-brake–only group, so product managers are either spec’ing pretty nice disc stoppers here or mixing and matching another road lever (mechanical 105 seems common on early 2020 bikes we’re seeing) to actuate mechanical disc calipers. But if your new ride rocks GRX brifters, a modified pivot position (Di2-level only) makes the levers noticeably easier to use from on top of the hoods. If you keep pedaling after the tarmac ends, this really is a game changer. After spending a couple of days on a GRX-equipped bike, I can say with confidence that they’re the best brifters I’ve ever used by a wide margin — the ergonomics and brake levers really are that good.

Shimano GRX brake levers also offer powerful stopping from any hand position.
With "sub" levers, the bar gets busy but offers powerful stopping from any hand position.
Courtesy Shimano

GRX also offers clutched derailers to keep chain slap to a minimum, flat-mount calipers for most modern gravel and gravel-adjacent bikes, and nifty “sub” brake levers mounted on the tops like cyclocross levers. These mini brakes are part of the closed hydraulic system, so I’m told you still bleed them like normal from the main levers and the “subs” are simply part of the line. Practically, I found them handy on short undulations in climbs where I was comfortable on the tops without needing to shift, but the ability to make a little panic stop was appreciated. The downside is that with a more crowded cockpit, many handlebar bags are going to be out of the running. I was unable to use a North St. Bags option I like for day rides, and even a Revelate Feed Bag was a bit of a challenge to strap on without interfering with the levers.

The group also includes a GRX wheelset available in 700c and 650b diameters. The sizes share a tubeless design, 24 spokes, thru-axles, 21.6mm internal widths, and Centerlock disc mounts. The 650b wheel and RX400 2x10 would be the lowest possible gearing option in a complete GRX build.

My time riding the group has been aboard a new GT Grade, which had its stock Tiagra group upgraded to the top-end GRX 2x11 Di2 group by a blue-shirted brigade of Shimano techs. Point being, this bike was built by real pros, and it shows. And while most touring cyclists won’t spring for the electronic Di2 shifting, we do hear from plenty of riders with hand issues, such as arthritis, who prefer the light touch of a Di2 button over the full-on push of a mechanical shift. Still, it ain’t cheap, nor is it probably much sought after by most.

Testing Shimano GRX drivetrain in Montana
Fine testing grounds for a group aimed at gravel and adventure riders.
Courtesy Shimano

All that said, I did plenty of shifting in Northwest Montana as a pair of tough rides on varied surfaces pushed both bike and rider in a big late-season effort. I bottomed out the 31-34T low end for sustained climbs and even managed to spin out the 48-11T on one long tarmac decent, but for the most part kept the front derailer firmly positioned in the smaller ring. Shimano’s shifting is always precise, but Di2 is on another level with every shift perfectly falling into place with a pleasant little whir from the servo motors. Honestly, it’s a bit addicting — ride Di2 at your wallet’s peril. 

So like SRAM’s Eagle drivetrain more or less banished the front derailer on mountain bikes to the dust bin of history, can GRX put the triple out to pasture? Not quite. If you’re a credit card tourist or committed to fast-and-light packing, GRX is an intriguing option for your next ride — especially if your steed pulls double duty as an unloaded backroad, cyclocross, or supported event bike. But if you’re packing for the roads barely traveled or prefer a pile of creature comforts, GRX just can’t match the low end gearing offered by an old-school 3x9 rocking the very best 2009 had to offer. Truth is though, that’s not most cyclists — not even most adventure cyclists. And for those of us only touring on occasion and limited by space on the rack or the credit card to a slimmed-down stable of bikes, something sporting 40mm of rubber and a GRX 2x drivetrain offers a path to almost anywhere.


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Dan Cross June 15, 2020, 8:52 PM

You say the m772 is still made but everywhere I look has said it's discontinued. I managed to just score a couple of remaining inventory.

You also said that for years all you had to do is combine a set of road shifters with mountain derailleurs. That may have been true for the rear but not in front. That would require some type of adaptation to change the pull ratio.

You also said nothing about the cost or longevity of these chains.

Alex Strickland June 18, 2020, 1:51 PM

Hey Dan, we checked w/ Shimano and indeed the M772 has been discontinued since publication of this post. They still offer two Deore models that are compatible with M772 drivetrains (RD-M591 and RD-M952). There is also an Alivio (RD-M3100) option. They say, "in the long term, the Alivio will be the go-to replacement for 9-speed touring drivetrains."

Touring triples setups with "brifters" spec road front derailers to deal with the pull ratio issue (the Trek 520, for example, uses a Sora road front derailer with an Alivio mountain rear for its 3x9 drivetrain).

As for chains, Cycling Tips did an extremely in-depth analysis of chain durability and the newer (narrower) 11 and 12 speed chains from Shimano considerably outperformed older 8- and 9-speed versions in durability tests. An interesting read!

Dave January 29, 2020, 11:09 PM

The new GRX parts are more versatile than advertised. I set up my wife's Trek FX6 hybrid with the GRX 48/31 rings and the 11-42 cassette, with Shimano flat-bar road shifters. Works really well!

Mehrdad Erfani March 13, 2020, 1:49 PM

Hi Dave!

I am looking doing this exact setup ... Can you please share your setup?

The best "approved" chain capacity is 40T which would max me out at 11-34T in the rear and front crank of 48-31T. I know and have pushed the Chain capacity limits in the past, but it is always more comforting when someone has already tried an "unapproved" combo.

Can you please share your component setup ( what FD, and RD you used, and did you use any extender and/or adjusted the B screw to clear the RD, etc. )

Thank you in advance for your help.

Dave B October 5, 2019, 8:11 PM

Shimano hasn't really abandoned the triple crank, they just don't sell them here in the US. Their "Trekking" cranks (FC-T8000 and FC-T781) are available in 48/36/26 format and, combined with an 11x32 or 11x34 10 or 11-speed cassette, should handle nearly any touring condition. As mentioned, the problem is Shimano doesn't distribute them here and most UK and German on-line dealers now won't ship to the US. If you know anyone in Europe they could buy and ship them to you privately.

Gary P April 11, 2020, 9:42 AM

Those cranksets are really "mountain" cranksets, though, with Q-factors and chain lines that are suboptimal for a road bike.

Alex Strickland April 11, 2020, 11:12 AM

They're definitely not full-blown mountain cranks. A typical modern MTB crankset has a Q factor of somewhere between 166-176, depending on brand. Shimano's road cranks have a Q factor of 146mm and GRX is 151. So it's in between, for sure, but *far* closer to a traditional road spacing than MTB. If you're really sensitive to Q factor, I think they have some fancy XTR pedals w/ 3mm shorter-than-standard spindles, which could get you back to a road Q factor.

The wider chainline (2.5mm) does mean you'd have to pair a GRX 2x crank w/ a GRX front derailer -- no cross-compatibility w/ an existing road unit.

Kevin October 3, 2019, 3:11 PM

I just bought an Co-op ADV 3.1 from REI with 38/24 up front and 10sp 11-36 on the back., and I didn't buy the ADV 3.2 version because it had 40/28 in front. All in all, I'd have preferred 38/22 or 40/24--if Shimano can do a 46/30, they should be able to do one of those 16-tooth-difference variants. I do enjoy the double up front, but I also have no problem with my stable of triples either. Don't have a real need for 1X. Sorry SRAM.

michael September 29, 2019, 7:43 PM

I have no idea how much it cost Shimano to develope this new group.... but I'll bet it was big hunk of change. Then they missed the target by 50%. My touring bike has a (9*3) 22-34 low and I use it all the time. But 30-34 seems to be the lowest available with GRX. Couldn't they have just made a modified version of either their drop-bar brifters that pulls mtb cable, or a modified mtb derailleur that works with road pull ratios. Doesn't seem like rocket science to me.

Tomg September 27, 2019, 9:46 AM

I'm not sure what's wrong with 1x11 or 1x12? I bikepacked on one this summer and it seems plenty low and bigger jumps between ratios isn't really all that annoying. And maybe the budget-constrained traveler will end up with the lower priced 3x9 set-up anyway, which despite being inexpensive can be quite reliable. And then there is the "serious" tourists who have the cash, and they should spring for an internal hub bike anyway. You can get a bike that "does it all" but it won't do it all equally well.

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