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Gravel bike drivetrains: 1x or 2x?

By Spencer Powlison


One ring to rule them all … or it takes two to tango? Nearly every bike company has jumped on the gravel bandwagon in the last few years. That results in far more choices when it comes time for you to build up your dream gravel bike. So how do you decide between a single-chainring and a double-chainring drivetrain?

Let’s weigh the pros and cons of the two setups. We’ll start by considering the two basic quantitative differences between single- and double-ring setups, stuff we can easily measure. Then, we’ll outline the more qualitative differences that set the two apart.

A group of people riding bikes on gravel roads


Gravel is a new bike category, different from road, mountain bike, and even cyclocross, but they’re still subject to the same scrutiny in terms of weight. Lighter bikes are almost always more desirable.

As you’d expect, a single-chainring drivetrain with fewer components is lighter than a double-ring bike, all things equal. But how much lighter?

In the case of SRAM’s Force AXS drivetrain, a front derailleur weighs about 200 grams, and a double-chainring crank is about 46 grams heavier than a single-ring. Shimano’s gravel-specific GRX group also offers both options. Its double-ring crankset is 55-66 grams lighter, depending on chainring size, and it’s cable-actuated front derailleur weighs 96 grams. An electronic GRX Di2 front derailleur weighs 135 grams. So, worst-case scenario, a double-chainring setup adds 246 grams.

“If you’re looking at ultimate weight, then going one-by makes a lot of sense,” says Nick Legan, author of “Gravel Cycling” and Shimano’s road brand manager.

Do you care about 200-250 grams of additional weight? That’s your call. If you’re trying to wrap your head around what that weight means in the real world, a full, 21-ounce water bottle is about 650 grams.

Gearing — range and gaps

Kansas has a reputation for being “flat as a pancake.” Anyone who’s ever ridden the famous Dirty Kanza gravel race will tell you that is bogus. Nearly anywhere you find gravel, you find hills. That’s because beautiful, quiet dirt roads don’t usually take the direct, flat route from point A to point B. When it comes to bike gearing, you’ll have to consider the length and steepness of your hills as well as how fast you plan to ride up (and down) them.

The first gearing consideration is range: How much difference do you have between your hardest gear and your easiest gear? In terms of modern drivetrains, double-chainrings usually win this debate.

Within SRAM’s Force AXS drivetrain family, the easiest possible single chainring is 36 teeth and the hardest is 48 teeth. Combined with a 10-36-tooth cassette, one ring doesn’t offer the range of a 46/33- or a 48/35-tooth Force AXS crankset on the same cassette. You run into the same limitation with Shimano GRX, which only offers a 40- or 42-tooth single ring. That can’t match the range of a 48/31-tooth double crankset on a standard 11-32-tooth cluster.

“Sometimes, you’ll see a really strong rider with a one-by because they don’t need that gear range. They are climbing hills much faster, so they have a narrower range of speeds from minimum to maximum,” says Legan. “Don’t always look to elite riders to choose your equipment. Some of the gearing I’ve seen on their bikes at gravel races is truly impressive.”

Gravel bike with two chainrings
Fortunately, you can get a single-ring gear range close to that of a double-chainring setup using a wide range cassette. With SRAM products, you can opt for a Force 1 mechanical drivetrain that runs a 10-42-tooth cassette. For even more range, you can also run an Eagle AXS mountain bike rear derailleur with a 10-50t cassette with Force AXS shifters — colloquially known as a “mullet” drivetrain. Shimano also has an 11-42-tooth XT cassette that would work with a long-cage GRX derailleur.

Those wide-range cassettes all have a drawback, however. They have larger gaps between gears. As you shift through the cassette, you won’t always be able to maintain the ideal cadence and effort level, depending on the terrain.

“Oftentimes, one-by has a narrower total range, and sometimes it has larger jumps between gears,” Legan says. “On gravel, I’d admit I don’t notice the jumps as much as I thought I would, but a lot of roadies talk about wanting the tighter gearing.”

As you might expect, a SRAM AXS mullet drivetrain will be heavier in the cassette and rear derailleur — 352 and 354 grams, respectively — compared Force AXS, which weighs in at 309 grams for a 10-36T cassette and 326 grams for the rear derailleur. However, if you compare the mullet to a double-ring setup on Force AXS, that 71-gram difference is offset by the weight of the front derailleur alone.

Simplicity vs. complexity

Even a double-chainring devotee has to admit that there is a simple elegance to a single-chainring bike. SRAM has led the uprising against the front derailleur, especially on mountain bikes, and that technology has translated into cyclocross and gravel bikes.

Without a front derailleur, shifting logic is simpler. That’s good for new riders who don’t have the experience to know when you should (or shouldn’t) shift your front derailleur. Plus, without a front derailleur, you have one less wear item, one less adjustment to make when tuning a bike, and one less thing to go wrong when you’re out in the boonies.

“One-by is good for beginners,” Legan adds. “It’s easier because you don’t have to think about shifting too much. Plus there is less to maintain, it's lighter, and aesthetically pleasing — one-by has a lot going for it.”

In terms of maintenance, you might also argue that chainring wear is distributed between two rings on a double drivetrain, making that less of a concern than it would be on a single ring.

Gravel bike with one chainring

Rider background

As mentioned in the last section, SRAM has made front derailleurs virtually extinct on modern mountain bikes. Shimano has followed suit. On the road, however, you still see plenty of bikes with double-chainring drivetrains.

The great thing about gravel riding is it is a meeting place for riders who come from mountain bike backgrounds and those who come from the road. As such, drivetrain choice can sometimes reflect an individual’s prior experience. A single-ring gravel bike will feel more familiar to a mountain biker, for instance.

“A lot of our decisions with gravel are informed by our origins. If you’re coming from mountain biking, you have a certain experience and from road, it’s another experience,” Legan adds. “I’ve ridden mountain bikes for a long time, but I am certainly a road cyclist. The two-by system is home to me. That ‘s where I feel comfortable.”

Chain security

When we talk about current groupsets like SRAM AXS or Shimano GRX, we take for granted the fact that they all have clutch rear derailleurs. The clutch mechanism holds the derailleur cage tight, preventing chain-slap on bumpy roads. This also helps reduce the risk of dropping your chain.

It’s worth noting that previous drivetrain generations don’t always have clutch derailleurs. You might encounter some pre-owned gravel bikes with Shimano 105, Ultegra, or Dura-Ace, or others with SRAM Rival, Force, or Red.

With one of those drivetrains, you won’t have as much chain security. In that case, your best option might be SRAM Force 1, a single-chainring group that has been around for several years and always has employed a clutch rear derailleur. It also has a narrow/wide chainring, which is designed to hold a chain on. Double cranksets employ chainrings designed to facilitate shifting with pins and ramps, and those aren’t conducive to chain security.

If you ride mellow dirt roads, this may not be a problem. If you’re adventurous and often end up on chunky Forest Service roads or even some singletrack, a clutch derailleur could be … well ... clutch.

Spencer’s take

Up until Shimano and SRAM started offering clutch rear derailleurs for double-ring drivetrains, I was a devoted single-chainring rider. The roads and trails I ride are rough enough that I don’t want to worry about chain security. I also ride mountain bikes a lot, so it’s normal to have a wide-range cassette. Plus, the simple aesthetics of a single-ring look good.

However, I also like to race some gravel events, and I do notice the gearing limitation if I’m riding in a group. Sometimes I feel like I just can’t get comfortable with my pedaling cadence. Other times my gear range isn’t wide enough.

So, for my next gravel bike, I’ll choose SRAM Force AXS. It seems like the perfect combination of features for me.

Legan has a similar take, and I trust the guy. After all, he literally wrote the book on gravel:

“I’ve done Dirty Kanza several times — on singlespeed, two-by, and one-by,” he says. “Personally, I still resort to a two-by. Part of it is how I use my bike. I use it as my road bike, as well as my gravel bike with a change of wheels. Because of that, I’m going fairly quickly, especially in Colorado on long descents, so I don’t want to give up my top-end gear. I want maximum versatility, even if I have some overlapping gears.”


  • I solved the single speed problem on my Shi.ano Ultegra setup with a White Industries front crankset. It will run a double… Which I did for a couple years. Same crankset supports a single ring from a low of 32 up to 48. The singles have a special tooth profile to maintain chain contact and eliminate the possibility of of derailing. Works great. I called them recently to see if they have something for SRAM Rival/Force/Red eTap AXS and was told that it’s in the works.

    Donald W Moore on

  • I’m currently in the process of building a dream-come-true gravel bike, so I’ve been looking at details. According to my calculations, Red AXS 2x is 28g lighter than Red/XX1 AXS Eagle 1x, when considering derailleurs, cassettes, and cranks.

    Justin on

  • I’m 68 and still pretty fast and fit. I do 250± miles a week during the season. I’ve ridden most of my life but for some years after I got a drivers license. Like most my age I had road bikes before mountain bikes. Mountain didn’t exist till the eighties I think. The first mountain bikes had triples of course so no real learning curve coming from the road. Some twenty years ago I added a cyclocross bike to the fleet and built it up with a 9 speed triple. I don’t, and never planned to race cyclocross. I use it to avoid cars on clay and dirt mixed with as little pavement as possible. I also put a 9 speed triple on my primary road bike. I have a second road bike with an 8 speed double that is only used for mostly flat rides. I ride in north Florida where there are flat lands and also lots of rolling hills. There is plenty of climbing but nothing of the length you would find in the mountains. In January I bought my first full suspension bike which is equipped with a 1x 11 speed. I love the bike but hate the 1×. I’m a real cadence rider and like close spacing on the cassette. For this build I chose a 36 tooth chain ring and a 12-34 cassette. Compared to my hard tail 29r with an 8 speed triple I gave up one bigger and one smaller gear. This has proven to be a good choice for my area though I really miss that one smaller gear (That small gear is a 26f x 28r) on the steepest climbs on my local rides. The biggest problem I find with a 1x besides the limited range is you have the worst possible chain line in the biggest and smallest gears. A double or triple has a much better chain line in the biggest and smallest gears. That and the 11 speed drive train is far less durable than both the 9 speed and especially the 8 speed on the hard tail 29r. I measured the 11 speed chain length before and after the first ride, 25 miles, and it grew 1/4 inch. In one ride! Ridiculous.

    To me the 1x is the answer to the question that nobody asked. Another stage of planned obsolescence forced on us by manufacturers. If I could put a front derailleur on my plastic wonder FS bike I would. I’d be happy with a double with the 11 speed rear. But you can’t put a front derailleur on this thing. I love watching World Cup cyclocross and mountain bike racing. I can see the advantage of a 1x for racing at this level but the vast majority of cyclists do not race at all. I wish the manufacturers would keep this in mind when they design bikes. I will never again buy any bike that cannot have a front derailleur fitted.

    Kirk on

  • I just went to a 2x bike from a 3x and had the option of 1×. I’m still adjusting to the 2x as I liked to ride using the middle gear up front and jumping up or down a gear on rolly paths I ride. Then I’d use the rear to fine tune as needed. I can’t imagine using a 1x despite the weight advantage. Then again I don’t race and don’t do group rides where I have to keep up with others. Also, what about chain wear from bending the chain laterally due to a single ring? There are lots of articles about avoiding cross chaining with 2x and 3x, what do you do with 1x where you can’t “straighten” the chain by shifting up front?

    George H. on

  • This article isn’t a pro-con comparo of 1x vs 2×. This is a one-sided pitch in support of 1×.

    John Ohotto on

  • The awkward jump between ratios is greatest on the front chainring shift! I think tradition more than anything dictates the slow adoption of 1×. Mountain bikers seem less afraid of change and that’s where we see most new technology that slow migrates to road.

    Threadless headsets, sloping top tubes, disc brakes, hydraulics disc brakes, wide range cassettes, narrow/wide chainrings, tubeless tires etc were seen on mountain bikes first.

    Roadies are traditionalists so change is slow and met with skepticism even if its a beneficial change.

    Nate on

  • I have a gravel bike and I have been doing some kind of magic with the transmission, the rear derailleur is a 1x rival with a 10×42 cassette, I have thought to use a sram gx high clamp top pull (road style) for the front derailleur with some chainrings mountain sram gx 1000 (36 × 24). All this adorned with 11-speed hydraulic sram red shifters.
    I know that back works well, but the front derailleur I do not know yet, if this puzzle does not work I would like to use a 1x mtb crankset of 30 or 32 teeth.
    the very simple question, do shifters work with the front derailleur or better I don’t get in trouble and use the 1x crankset.
    I like the relationship very short because here in Colombia we have a lot of mountains and the trails have average slopes of 10%, I do not want a speed roller but I can do a lot of mountains without fear of giving up at 50 kms.
    I hope you can help me and that you have made me understand.

    Juan Becerra on

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