I rode both while preparing to build my gravel bike (Hakka MX, GRX Di2 50/34 w. 11-34). My experience with AXS as well as the experience of my riding buddies is that it's noisy and still throws the chain quite a bit. GRX is the classic Di2 experience, with a clutched RD. I love it -- battery lasts forever, fast and reliable shifts, etc. I use my gravel bike on the road quite a bit, which is why I went with a compact 2x up front.

My take? If going 2x, Shimano. 1x? SRAM.

Both groups work really well, but the extra cog (and extra small cog) on AXS really do make a difference for 1x use.

With 2x, Shimano just does front derailleurs better, and synchro (or semi-synchro) means you can, if you want, basically run the system as you would a 1x.

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Tech writer/support on this here site. FIST school instructor and certified bike fitter. Formerly at Diamondback Bikes, LeMond Fitness, FSA, TiCycles, etc.
Coaching and bike fit - http://source-e.net/ Cyclocross blog - https://crosssports.net/ BJJ instruction - https://ballardbjj.com/

Sounds like you’re set on 1x and I agree with your conclusion on the 10-50 gearing.

As fredly alluded to above, I think for 2x Shimano probably has the edge. I just ordered a 2x setup with GRX Di2 48/31 and 11-34. Better high, low, and spacing seems like a no brainer to me if you’re set on AXS/Di2 anyway.

I looked at both options you mentioned but ultimately went with Obed, partially for the GRX Di2 option (I went 2x but they offer 1x too). But I’ve never ridden AXS or Di2, just taking my experience with Shimano and SRAM mechanical and reading up on them both.

Well....my initial preference was 2x for some better road use gearing, but I wanted to be able to run a larger tire with a 700 wheel....up to ~45mm tire. Going 2x really restricts that. Open Wide is fine, Exploro is able to a 42....1 or 2x.

Di2 on both road bikes. SRAM AXS x1 on the gravel bike I've just built up. Parts/prep video here. Build video here. The SRAM setup on my gravel build is perfect. One side up, one side down. Simple. I have a set of MultiClics on order so I can be lazy and change gears while holding the top bars. The only thing I really miss on the SRAM setup is the hidden buttons to change screens on my GPS head unit.

On the gravel bike I run a 42 on the front and 10-52 on the back. I was told I'd spin out too quickly on open roads (haven't yet), I'd hate the gear spacing (it's fine), and I'd never use the 52 (I do). 🤷🏻‍♂️

I'm planning on putting a set of road wheels on the gravel bike later in the week to see if it's a 'do it all' bike or not. I suspect the 44 chainring might be the limiter with faster wheels.

*Edit: 42 on the front not 44.

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Shane Miller - GPLama
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Maybe take a look at the Obed Boundary, which fits 700x45 according to the website. Seems to check all your boxes. Can’t go wrong with either of the others, but it’s nice to have exactly the drivetrain you want when you’re spending all that money.

Just use the shimano 11-46 XT cassette if you want little easier gearing and want to stick with shimano. I believe shimano says the RD maxes out at 42, but I have ridden with friends who use a 46 with zero issues. for what its worth, I would always prefer shimano myself, but when I was building my gravel setup they didnt have their grx and I wanted 1x, so I went with sram force etap axs. couldnt be happier. but a shimano grx di2 1x sounds amazing too

I have my first rides in on my new Ventum GS1 with mullet AXS 42/11-50. Works very well. I ride di2 road, sram 1x force cross, and have MTB with 1x Shimano and SRAM.

The mullet AXS works well.

I agree Shimano front derailleurs are better. 1x? SRAM makes it work really well.

I’ve had 1x Di2 (D/A or Ultegra with XTR RD) on 3 gravel bikes (and 2x on current road bike) prior to current rig with Force AXS. IMO there’s little if any difference—other than SRAM is available and Shimano is hard to find.

Shifting quality is nearly identical, and current setup with 44t Wolf Tooth front ring and either SRAM 10-50 or e*thirteen 9-46 cassette has been flawless. For 1x SRAM’s 12-spd is a major plus if only for narrowing gear jumps and 10t cog.

If I were building a new bike I’d go with SRAM.

Both of the groups have their plusses and minuses.
I have been using 2x Shimano gravel DI2 for several years. My setup has been 34/50 for chainrings and 11-40 cassette.
Also using the Shimano climbing shifter than has both buttons on one side. And my Wahoo is paired with the D-fly.

Advantages to the Shimano setup
1.) Gearing is pretty well rounded and relatively small jumps
2.) Climbing shifter is really good
3.) I love having the top buttons on the Shifters to operate my Wahoo

Disadvantages to Shimano
1.) Even with GRX and a clutch the chain rattles and occasionally drops on rough terrain
2.) Front derailleur somewhat limits clearance for rear wheel
3.) Needs more wide range gearing options- Preferably with a 10 tooth cog

My SRAM Setup is a Red AXS Hydro setup 1x 44 tooth ring, 10-50 cassette, Hope brake calipers, and also experimenting with blips and multi-clips on the tops.

Advantages to SRAM
1.) 1x is pretty flawless
2.) 1x provides more clearance for big rear tire

Disadvantages to SRAM
1.) Big jump from 42 tooth to 50
2.) No Wahoo/Garmin compatibility
3.) The blips are pretty terrible. Hard to push the buttons, difficult to find a position on the bar that is out of the way, and easy to press. Still working with the multi-clics. Multi-clics are easier to press, but they stick out and get in the way depending on how you hold the tops
4.) Jumps between gears are larger than with Shimano

This ^^^^^.

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Colorado Triathlon Company, CO2UT 2021, Crooked Gravel 2022, Steamboat Gravel 2022

What about the brakes? SRAM mountain bike breaks are often swapped out for Shimano. Scott even puts Shimano brakes are top of the line SRAM equipped mountain bikes.

That may drive my decision as much as the shifting. Obviously, you can't SRAM for shifting and Shimano for breaking on a drop bar gravel bike.

SRAM really seems to have gotten their s**t together, brake-wise, over the last couple/few years. It's not the gigantic issue it was.
Frankly, I've heard of more people having issues with the Shimano road/gravel brakes than with the SRAM, and I've had a couple of broken pistons myself.

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Tech writer/support on this here site. FIST school instructor and certified bike fitter. Formerly at Diamondback Bikes, LeMond Fitness, FSA, TiCycles, etc.
Coaching and bike fit - http://source-e.net/ Cyclocross blog - https://crosssports.net/ BJJ instruction - https://ballardbjj.com/

gravel? mullet eagle/force axs. complicating this now is that it got cheaper, both on the eagle side and on the axs etap side (with rival).

i'm building up a fleet of open wides for the compound, and i'll probably be opting for cheaper eagle and rival etap, except perhaps for the force crank. my person gravel bike is an open wide with force throughout from the crank forward and eagle in the back, with ENVE G27 650b wheels and schwalbe 53mm g-one bites. on the fleet i'm building it'll be those tires, but HED emporia wheels in 650b. and 10-50 12sp on everything.

what gplama said about the shifting. this is one reason that electronic is better than mechanical. it's very intuitive, when you're so tired you're stupid, left shifter shifts the derailleur left, right shifter shifts it right.

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Dan Empfield
aka Slowman

I purchased a Cannondale Topstone with 1X GRX cable and put 2X DI2 on there. Personally for the riding I have done I would have enjoyed a 1X far less as I like the closer ratios, use a bigger gear than a 1X 42/10 and with the DI2 I can think about my shifting far less. That aside the GRX DI2 is flawless and I even installed the satellite shifters on the tops that is a sweet touch.

Another thing to consider is if you’re already in the Di2 camp you don’t have to learn anything new with GRX (same charger, same software, same shifting, same way of bleading brakes, same chains, same cassettes, ...)

I’ve never ridden AXS, but GRX is brilliant.

Yup......I have 2 other bikes running Di2 and just for simplicity sake went GRX Di2 on my new gravel bike. Slowman's review of the Open UP.ER. sold me and I went that route. 42T 11-42 gearing is almost perfect for me where I ride.......I did a ride last week where a 40T-42 would have been nice at times, but might have been easier to walk at that point.

Had Ultegra 1x Di2 on two different gravel bikes over three years (and have on current road bike). Works great, clean shifts and only real issue I had was more frequent bleeds than expected. Gearing is a little tricky depending on where you live but fine. Battery life is great, just have to remember to charge occasionally.

In December I got a new bike with SRAM mullet build, 44 Wolf Tooth upfront and e*thirteen 9-46 cassette. SRAM wins on gearing with 12spd closing the jumps between cogs and a better range. I’ve also come to like the slightly larger levers, especially for mixed terrain. Battery life is shorter, I just charge weekly when I plug in bike computer and carry an extra on big days.

Have a new ENVE bike on order and went with SRAM. Don’t think you can go wrong with GRX (but probably can’t find it) or SRAM, just a matter of preference.

As this thread popped back up, just wondering what you decided upon? If Shimano, are you still waiting for the bike?!? ;)

A few months ago, I got an Open U.P. with Force/Eagle mullet (40 x 10/50) and could not be happier. Very similar to Slowman's fleet, with 650b wheels. I do admit, however, that having Di2 on my road bike is somewhat inconvenient, as I sometimes have to "remember" how to shift the bike I'm on that day! For that reason, I will strongly consider Sram when it's time to upgrade the road bike.

I ended up ordering an Open WI.DE. with GRX Di2 1X (42T 11-42), Easton carbon cockpit. Great bike and loving everything about it. I actually had no issues with the build...ordered and delivered in a matter of a few weeks. Only item I had an issue with was wanted Reynolds ATRX wheels which had delayed availability so I switched to Zipp 303s wheels instead.

Nice! Sounds like a great build; hope you enjoy.