Gravel bikes these days are divided between 1x and 2x groupsets and it is up to us to decide which solution we want. This is not an easy task, believe me, but after testing a couple of gravel bikes with 1x groupset (both Shimano and SRAM) I think I can help you decide. Or at least I can show you the differences that I can see so you can make a more informed decision.
My site is all about gaining as much comfort as possible without losing the fun of the ride in the process. Comfort is a big topic so to make things easier I will break it into two main areas: Cadence and Convenience. Cadence, because this is the main complaint that people make towards 1x groupsets and convenience, because this is the main advantage, at least for many, of a 1x drivetrain.
To make everything more interesting, I will compare rather extreme cases of both 1x and 2x drivetrains. 1x is going to be represented by SRAM Eagle AXS wireless rear derailleur with a huge 10-50 Eagle cassette (12 gears) paired with 42T chainring at the front and SRAM Force eTAP leavers. Exactly this is on Canyon Grail Grail CF SLX 8.0 ETAP that I am currently testing (a full review coming soon).
The 2x drivetrain is represented by my own benchmark bike (Jamis Renegade Exploit) but it is no ordinary setup either. At the rear, I changed the cassette from 11-32 to 11-40 to get more range and better climbing possibilities (to make this work I also needed to replace the rear derailleur for Shimano 7000 GS long cage one and use a longer chain). At the front, there is a standard Shimano 50 / 34 crankset but everything is paired with brand new GRX 810 leavers (because I wanted to finally have fully hydraulic brakes – up to this point I was using a TRP Hy/Rd brakes).
Round 1: cadence
This is a very complex topic, so let’s break it into smaller parts. First is the speed that you can travel with at the lowest and highest possible gear. To calculate that I used this website and the data says that at 90 RPM cadence the speed you will achieve on a 1×12 setup is 50 km/h (700c 40 mm wheel, 42×10 gear ratio). At the same cadence, my benchmark bike can ride 4,2 km/h faster (50×11). Not a lot but it can become handy when you ride downhill a lot. Yet when you go down, you also have to go up and in this scenario, the difference is even smaller. On 1×12 setup at 90 RPM you travel at 10 km/h (42×50 gear ratio) and on my 2x setup it is 10,1 km/h (34×40 gear ratio). It means that going is very much the same hassle on both bikes. This I can confirm because I climbed on both bikes on the same hill and I was equally exhausted at the end (maybe it is time to really work on my stamina because 34×40 gear ratio is quite forgiving…). Of course, the difference could be bigger in 2x favor when changing the front crankset for GRX 48 / 31 (which I will do on my new benchmark bike), but then the max speed would be slightly lower also (but still you would travel faster than on 1×12 setup of Canyon Grail bike).
So, the max and min speed difference is not that differentiating between two tested setups but now it is the time to talk a little bit more about the jumps between the gears. This is the area where 1x drivetrain is criticized the most and now I can see why. It is all about the bike you have and the rides you usually do. I normally ride alone and my steel bike is not that power efficient and fast so it could work with 1x setup. But on a fast carbon bike like Canyon Grail you start to notice that the 1x drivetrain is somehow limiting you. On 2x setup you can find the cadence you want and on 1x it is more like riding at the cadence your bike is proposing you. You can feel it both when accelerating but this is even more obvious when you want to find convenient traveling speed. When riding on Canyon Grail there were situations when I felt that I could travel a tad faster but when I switched the gear, it became too tiresome to maintain the cadence so I had to slow down and then switch back to the previous gear. It is somehow frustrating not to be able to ride at the edge of your (in my case rather limited) abilities. I really think that on my steel Jamis Renegade bike I would not feel that frustrated when riding on 1x setup but still, now I can appreciate the gear range that 2x drivetrain offers. This, to be clear, comes not only from different gear ratio of the rear cassette (which becomes obvious when you pass the 24 cogs mark) but also because of the lack two chainrings at the front (which you can change to find the best combination with the rear gear). Also, you have to bear in mind, that I use 11-40 rear cassette and when using something more traditional for 2x Shimano setup (11-34) the gear jumps would be even smaller through the whole range.
So, who wins the cadence battle? In my opinion, 2x drivetrain is simply better and more suited to my abilities. Especially, because I mix the rides (40 on the tarmac, 60 on gravel) and the gear range of my current setup suits me better. But if you ride mostly on gravel and singletrack and/or you have powerful legs, then 1x setup could be more beneficial (it will force you to ride harder because you will be on a gear that you would normally not use).
Round 2: convenience
This is a very interesting battle because after riding a couple of 1x bikes I really think that 1x is much easier to live with than 2x drivetrain. Let’s start with the shifting. On Grail there is ETAP Electonic shifting that works beautifully. You use left shifter to go for easier gear and right to go for a harder one. You click and it is done. No matter if under load or not, SRAM ETAP is a joy to use and you don’t need to think about the gearing at all (but you definitely have to think about the battery being loaded because otherwise there will be no shifting at all). But even a Shimano GRX 1x drivetrain offers the simplicity that can be very enchanting (you simply use one lever to go up and down). On the other hand, you have the 2x setup where, yes, you can find your perfect gear but you have to work harder to make it happen (shifting both rear and front gears). Then, you also have to remember not to cross-chain too much which means not using the biggest front and rear rings at the same time (which in real life somehow limits the gear range you can really use on 2x setup).
Yet this is not the end of the convenience story. Not at all. My bike is not that new anymore and I can really hear the downsides of having two chainrings at front. What I mean by that is the crankset movement that makes the derailleur adjustments much harder and without that, chain robbing the derailleur will make you at least, slightly irritated. With 1x drivetrain, you don’t need to worry about anything. You just keep the chain lubed and enjoy the ride. No adjustments needed even when your crankset is not working in perfect line anymore. 1x drivetrain usually also means a bigger tire clearance but to be fair, new GRX derailleur is designed to achieve the same result with 2x setup. Old Shimano 105, that I have, was causing a lot of issues when I was experimenting with big tires at the rear (basically I could not use the bigger chainring in those situations even the frame itself was still having enough clearance to accommodate the tire).
So, who wins a convenience battle? 1x setup. Yes, you can find the right gear more easily on 2x setup, but other than that, I really think that nothing can beat simplicity of a 1x drivetrain.
And the winner is….
I don’t think that we can a clear winner in this battle. For me, and my style of riding I think that I will stick with the 2x system and change the front crankset to 48 / 31 for even lighter gears when climbing. Yet I can totally understand those who fall in love with 1x setup. The easiness of use is really addictive and after spending a lot of time with SRAM ETAP 1×12 setup it was hard for me to go back to my 2x bike. Yes, part of the charm was definitely the electronic shifting but still, I really enjoyed the simplicity of 1x setup. Yet at the same time, the irritation of not being able to find the perfect gear was too frequent for me to ignore and that is why, especially with a really fast bike like Canyon Grail, I still would go with a proper 2x Shimano GRX setup…