Well, here we are. What day is it again? We're not sure either. In the spirit of keeping the juices flowing in this time of the great shutdown, we bring you a battle for the ages. Or, for the past ten years. As storied manufacturer Campagnolo has slid more into the niche end of the cycling market, one of the most oft-debated equipment questions is the choice between the remaining two drivetrain heavyweights: SRAM and Shimano. With the advent of GRAVEL in the past few years, the question has intensified as each brand has approached the “new” market segment with differing tacks. Today we’ll be taking a (subjective) look at both of their electronic approaches to the genre on a pair of Páramo gravel bikes we recently built for clients in California. For full galleries of both bikes, scroll on down to the bottom of the page.
SRAM kept their first-generation electronic eTap kit out of the dirt when it was introduced in 2015, but when the second, updated-to-12-speed AXS version landed, we breathed a sigh of relief. Full cross-compatibility between its road and dirt-oriented parts meant one could get weird with it. Road shifters, mountain derailleurs? Yep. Do you want your road shifters to operate an electronic dropper post? Sure, it can do that. And it's wireless, at least on the shifting side. What’s that mean? It means no wires. No unsightly holes in frames, no wiring harnesses running through downtubes, no junction boxes, and as clean a cockpit as one can dream.
While the standard “road” eTap AXS setup is a 2x12 speed drivetrain, it’s limited by gearing. The maximum rear cassette size is 10-33t, which, even when paired with a combination like Rotor’s 46 / 30t direct-mount chainrings, can be a bit on the taller side. And, the Red / Force AXS rear derailleur’s light hydraulic clutch (a mechanism that maintains chain tension with the derailleur) isn’t really up to true off-road duties when it comes to chain retention. Believe us, we tried. Hard.
Hence, we favor their dirt-going 1x “Mullet” setup for drop-bar gravel builds, using SRAM’s road shifters with their XX1 or XO1 AXS MTB rear derailleur. While there’s no option for a front derailleur with this arrangement, the mountain-carryover 12-speed Eagle cassette is an enormous 10-50t dinner plate, giving us the low gear we favor for steep pitches while still keeping speed on the flats and descents. Gearing gaps are on the bigger side, but on dirt, we find they become less an issue than during steady-state road efforts.
SHIMANO GRX snuck onto the radar last year without much fanfare. Its electronic components (812, in Shimano nomenclature) retained all the same Di2-standard wires, junction boxes, batteries, and buttons as its road-going siblings, Ultegra Di2 and Dura-Ace Di2. And yes, it still “only” goes to 11, like the road kits. Shimano’s legendary glacial speed when it comes to product releases likely means we won’t see road / gravel 12-speed drivetrains to the SRAM / Campagnolo anytime soon. But that's no matter, because where GRX Di2 changes key in the Shimano lineup overshadows the lack of a spare cog.
First, where we're most excited: Lever design. GRX Di2 offers a wholly new approach to the design of a drop-bar lever for dirt. Ergonomically, they’re shaped to work well with the latest crop of flared drop bars, and a wider lever blade with shorter reach makes them approachable for riders with smaller hands. Their real party piece is the transition of Shimano’s MTB brake tech to gravel, which moves the pivot of the brake lever up, giving the rider far more braking control from the hoods.
Second, gearing options. Shimano’s done us the service of creating clutched derailleurs for both 1x and 2x setups, along with a trick 48 / 31t crankset. While we're partial toward 1x setups for dirt bikes, the ability to go 2x opens up possibilities, and Shimano’s frankly - awesome - front shifting leaves us no questions about it when the day comes.
Finally, GRX Di2 is endlessly customizable when it comes to button functionality, and spare hidden buttons near the top of the lever can even change your head unit’s display if that’s your jam. But, it does require the wireless transmitter “upgrade” to add to the wiring harness.
"HOW THEY STACK UP" is always going to feel a bit nit-picky. After all, at this level of componentry, both are extraordinarily capable and will never hold you back. Frankly, we're now in the realm of personal preference.
From the SRAM AXS side of things, we wish there were a couple of other in-house 1x gearing options beyond the massive 10-50t. Perhaps a tighter-range 10-42t? And, as always, shifting speed is a hair slower than Shimano Di2, and the drivetrain is a bit noisier than its Japanese counterpart. But, in our humble opinion, the “click” feeling of the shift button is far more positive-feeling with SRAM, something important when wearing gloves or bouncing around in rough terrain. But, their lever shape is polarizing - those with smaller hands tend to struggle with the big levers, and the reach adjust can only go so far, whereas GRX shines in this aspect. SRAM also offers fairly clean powermeter integration with their Quarq spiders, if performance is an aspect to the ride, something Shimano lacks.
Shimano GRX, on the other hand, hits some very high highs, but also manages to fall short in some other fairly critical measures. Gearing is an issue, even with the 2x setup offered. Shimano has yet to offer an 11-speed “minidriver” cassette setup to the SRAM, one that allows for a 10t (or even 9t) smallest cog, which in turn would offer greater range. Technically speaking, the largest cogset the 1x rear derailleur can fit is a 42t, though we've run a 46t setup without modification. The astute viewer will note that on the GRX Páramo, we've chosen to fix this issue with a third-party solution from Garbaruk, a Polish machine house, because we're insane. The aftermarket 11-speed 10-50t cogset paired to their oversized pulley cage expands the GRX derailleur’s capacity, and the XD driver gives it a range as big as a standard SRAM Eagle setup (with one fewer cog). And yes, it works just as well as the standard (and flawless!) Shimano setup. That said, having to use third-party parts to achieve the same level of gearing range as a direct competitor can lead to frustration. Shimano’s electronic shifting performance, however, is still unmatched. Clean, fast, dead-on shifts with minimal noise are the calling cards of a Di2 drivetrain.
Finally, where Shimano and SRAM really stand apart from one another is in ease of every day use and maintenance. SRAM’s design mentality, especially since their eTap introduction almost five years ago, seems to be one mindful of the end-user. The wireless aspect of the group keeps it free of a lengthy spreadsheet of electronic parts with a plethora of digits in their names. A Di2 bike uses no less than four wires of differing lengths, two junction boxes, one battery, and one splitter, all of which can change depending on the size of the bike, or preferences for things like the aforementioned wireless transmitter. None are necessary with AXS. Updating the firmware and adjusting preferences with SRAM’s kit is relatively easy with their smartphone app. Shimano requires the aftermarket wireless transmitter to update via their difficult to use app, and doesn’t offer much in the way of real-time diagnostics. Not lucky enough to have the transmitter? Well, there’s a desktop application. That only works on Windows. In our current DIY culture, it seems a bit silly that Shimano has largely ignored ease of use and simplicity. But, that's always been Shimano.
At the end of the day - is there a verdict? Short answer: No. We like both quite a bit, but for different reasons. And we’ll leave it at that.