If you're shopping for a new cyclocross or gravel bike (or building a new frame up from scratch) you choice of components has two primary competitors - Shimano's GRX, or SRAM's XPLR AXS group. While you'll certainly find bikes that have components from other brands, or different series components from these two brands, these two specific groups dominate the space for drop bar bikes ridden in the dirt.
Canyon's popular Grail gravel bike, for example, is offered with choice of SRAM XPLR AXS or Shimano GRX - same frame, same paint, same wheels! And since the price is similar too, the differences between the two systems might not be obvious at first glance.
Let's take a look at some of the pros and cons of the GRX and XPLR AXS groups, and how you might choose between them.
Overview of Shimano GRX
GRX is Shimano's name for components intended for drop-bar bikes ridden on a variety of surfaces - gravel, cyclocross, bikepacking and so on. For riders already familiar with Shimano's road groups, there are some natural comparisons - the "800 series" GRX parts are loosely equivalent in performance and price to Ultegra, the GRX "600 series" lines up with 105, and finally the "400 series" equates to Shimano's Tiagra budget road group.
Note that there isn't a "Dura-Ace" equivalent in the GRX line-up at this time.
- GRX RX800 has both mechanical and electronic shifting options, and is available in 1x11 single chainring or 2x11 double chainring options.
- RX600 is mechanical only, and has the same 1x and 2x options and 11 speed cassette.
- RX400 is mechanical only, 10 speed, and comes in a 2x traditional double crankset only.
If you're already riding a Shimano-equipped road bike, transitioning to GRX is easy, with the shifter buttons and operations in the same locations.
GRX is designed for off-road riding, with lower gear ratios, and includes some technical changes to permit the use of wider rear tires than might be wanted or possible on a road bike. You get hydraulic disc brakes at each level for reliable, powerful braking, and the brake lever hoods have a tweaked shape, allowing you to brake more from the hoods without pinching your fingers against the handlebar.
Unlike Shimano's newer Dura-Ace and Ultegra groups, note that top-end GRX is still 11 speed, not 12, and if you choose GRX Di2 instead of mechanical Di2, it also has the "wired" electronic shifting, not the newer "semi-wireless" setup found on the newest Shimano Dura-Ace and Ultegra road groups.
This means that GRX might seem "dated", is a 12 speed GRX group with the semi-wireless electronic shifting option on the horizon? Given Shimano's move to 12 speed on the road, as well as updated 12 speed MTB components (XTR, XT) a future 12 speed, semi-wireless GRX seems certain. But it doesn't exist yet.
Overview of SRAM XPLR AXS
SRAM (parent company of SRAM, Rockshox, Zipp, Avid, etc.) builds their XPLR line (say it "explore") as a direct competitor to GRX - it's also intended to meet the needs of riders using drop bar bikes in the dirt. Think cyclocross, gravel racing, bikepacking, off-road touring.
Unlike Shimano, who supplies the drivetrain, wheels and brakes all under the Shimano name, XPLR includes multiple SRAM brands - SRAM XPLR for drivetrain, an XPLR Rockshox suspension fork, dedicated XPLR Zipp wheels and handlebars, and so on - even XPLR tires if you like.
Also in contrast to Shimano GRX, with multiple crankset and mechanical/electronic options, with SRAM's XPLR AXS there's only one choice - wireless shifting, and a 1x single chainring crankset mated to a wide-range cassette. All the XPLR drivetrain components resolve around SRAM's AXS (say "access") wireless shifting and come in Rival, Force, and Red (low-end to high-end) tiers. Generally, these components interchange, they just get lighter and more expensive as you go up the line.
XPLR AXS uses completely wireless shifting - there's a battery in each shifter, as well as at the rear derailleur, with no internal wiring connecting the parts.
Ridden a SRAM-equipped AXS eTap road bike recently? Then you already know how their wireless shifting works - XPLR has just been updated with new rear derailleurs, single-chainrings optimzed for gravel bikes, and the wide-range 10-44 tooth cassette for low gears.
XPLR includes a couple components not offered by Shimano:
- Rockshox Rudy XPLR suspension fork - Rockshox's Rudy fork is a short-travel suspension fork for gravel bikes, designed to take the edge off bumps and reduce fatigue on all day rides. This is dead weight on a 'cross bike, but I can see the appeal of such a fork on bumpy gravel terrain.
- Reverb XPLR AXS suspension dropper seatpost - it's wireless (of course) so you need yet another battery. But the clever design combines the features a suspension seatpost for comfort, with dropper capabilities to lower your saddle on rough terrain. As with the Rudy fork, you wouldn't use this on your cyclocross bike, but it's a nice option for gravel on challenging, steep terrain. You can activate the dropper post from the handlebar-mounted buttons, very clever and convenient.
Shimano GRX Di2 (wired) electronic shifting vs. SRAM XPLR AXS (wireless) electronic shifting
Shimano's Di2 (pronounced "dee-eye-two") was launched way back in 2009. That generation of components is obsolete now, but the name - digital integrated intelligence - lives on in the current GRX group. While Shimano's Dura-Ace and Ultegra groups have moved on to 12 speed, GRX is still 11 speed.
Note that you don't have to have Di2 to get GRX, because GRX still has a mechanical shifting option. That's in sharp contrast to SRAM, where it's all or nothing - there's no mechanical shifting option on XPLR AXS.
The 11 speed Shimano GRX Di2 and 12 speed SRAM XPLR AXS both have the electronic shifting option, but it's implemented differently. SRAM's XPLR AXS is wireless - the shifters and rear derailleur are not connected by wire, instead communicating via radio waves. Shimano's GRX Di2, in contrast, uses internally-routed wires to connect the shifters to the system's battery and derailleurs. This means you only have a single battery to charge in order to power the system, which is convenient, but bicycle assembly is much more complicated to setup, due to the internal wiring. The SRAM wireless system is much faster to assemble (though to be fair, you only do that once, on new bike day).
Remember that we're only taking about wireless or wired shifting, which is exciting - no cables to stretch or become contaminated with dirt, affecting shifting performance. Hydraulic brake lines still have to be hooked up, filled with fluid, and potentially routed through the frame, if your frame/fork uses internal routing for the brake lines.
12 speed vs. 11 speed
SRAM XPLR AXS wireless components are 12 speed, and thus compatible with the SRAM Eagle AXS mountain bike cassettes, creating some interesting drivetrain choices and possibilities for cyclocross and gravel, because the components are cross-compatible.
Shimano GRX is sort of "orphaned" currently, because Shimano's Dura-Ace and Ultegra (road) and XTR and XT (MTB) have moved to 12 speed. This means that there is minimal cross-compatibility between GRX 11 speed and the 12 speed road and MTB components. The GRX 10 speed components are of course, also not compatible with the 12 speed gear.
Shimano GRX Di2 should have a longer battery life than XPLR AXS, because it's wired internally, there are no radio transmitters or receivers that suck battery power. In fairness, SRAM XPLR AXS batteries still last a very long time, but it's something to consider if you'll be away from wall charging for an extended period of time, like on an extended off-road tour.
SRAM's claimed battery life is 600 miles / 1000 kilometers, riders might reasonably expect 2 or 3 times that on GRX Di2. Real-world? Riders willing to charge once a week will probably see no difference between the two systems.
XPLR AXS shifter levers use separate, disposable coin-type batteries that can't be recharged. If I was traveling for an event, I'd bring some of these with me in my toolbox.
Crank-based power meters for the Shimano GRX and SRAM XPLR AXS groups aren't at parity with the road groups, yet. Perhaps SRAM will bring their existing Quarq power meter design to the XPLR AXS crankset in the future, but today, gravel and cyclocross riders will want to look elsewhere for crank-based power monitoring. Similarly, at some point we might see a Dura-Ace inspired crank-based power meter come to the GRX group (perhaps as part of a future 12 speed GRX re-design.)
Pedal-based power meters, like Garmin's double-sided Rally pedals, might be a better bet for this type of riding currently.
SRAM's mobile app is better
If you're considering an electronic shifting drivetrain, you're probably also comfortable in the mobile phone app ecosystem. SRAM has the edge here, allowing you to perform common tasks on the XPLR AXS group using your iPhone - firmware updates, initial system setup, and reviewing the battery charge level.
While Shimano's "E-Tube" mobile app has similar capabilities, the required Bluetooth module on the bike isn't part of the base GRX Di2 setup (although it can optionally be added.)
Shimano GRX Pros and Cons
SRAM XPLR AXS Pros and Cons
What GRX Di2 and XPLR AXS have in common
- Shift with the click of a button - like clicking the mouse on a computer
- Fast, reliable shifting
How GRX Di2 and XPLR AXS are different
- 12 speed (SRAM) vs 11 speed (Shimano)
- Shimano's GRX group (both Di2 and mechanical versions) use Shimano's "classic" freehub design. SRAM XPLR AXS needs the newer XDR driver body. XDR is becoming much more common and widely available, but there are still many more Shimano freehubs out there.
- Batteries - SRAM's XPLR AXS system uses separate batteries for the rear derailleur and each shifter, while Shimano GRX Di2 uses a single battery that powers the entire bicycle.
Shimano GRX vs. SRAM XPLR AXS - which should you choose?
Both these options are excellent, and I'd love to own bikes equipped with either of these groups. That being said, there are some key reasons to choose one or the other.
- Consider your other bikes - if they're all equipped with Shimano or SRAM, your next gravel or cyclocross bike probably should be, too. It's a hassle to switch between two different shifter setups. It makes sense to stay within the same ecosystem.
- Many experienced riders also have an entire garage full of wheelsets to suit the conditions of the day. You should carefully consider your existing wheels before choosing the SRAM XPLR AXS kit, because the XPLR AXS cassette requires SRAM's XDR compatible driver body on the rear hub. If you have older wheels, make sure they're convertible and confirm that the driver body is available. Shimano's GRX, in contrast, uses Shimano's "classic" style freehub body, which had wider availability since it's a much older design.
- Mixing and matching? Generally, Shimano's Di2 stuff doesn't interchange. You can't use an XTR rear derailleur with a Dura-Ace front, for example, so if you're planning to ride a GRX Di2 bike, expect to keep it all the same. SRAM has the edge in this area, with wider cross-compatibility of wireless components; allowing you to use MTBR rear derailleurs with road shifters or vice-versa. Keep this in mind if you have Shimano 12 speed road bikes - don't expect cross-compatibility with 11 speed GRX.
- Shimano doesn't have a competitor in electronic budget shifting. If you want Di2 GRX, the top-end GRX 800 series is your only option. SRAM, in contrast, offers electronic shifting at every tier, from high-end to entry-level.
- Gotta have the best? If impressing your riding buddies is a priority, SRAM may have the edge, because their XPLR AXS group is available in the top-end "Red" tier. The top tier GRX, in contrast, really lines up with Shimano Ultegra specs, and there's no Dura-Ace equivalent. There's an opportunity here for Shimano to build a flagship, 12 speed, semi-wireless GRX Di2 group in the future for serious cyclocross and gravel racers who want premium equipment.
- You want a mechanical drivetrain. If you're a traditionalist not interested in electronic shifting, Shimano GRX is your choice, as SRAM does not offer a mechanical shifting XPLR option at all.