It’s a debate that never seems to end, and anyone considering buying or building their next gravel bike has likely spent at least some time weighing their options.
But before we get to the heart of the matter and try to decipher which of the best gravel bikes will suit your needs, it first makes sense to start with a basic understanding of the discussion. Those of us who are deeply immersed in bike technology can sometimes take it for granted that everyone understands the ins and outs of it. Not everyone does, so let’s start with what are we talking about here? What do the terms 1x (one par) and 2x (two par) refer to on a bike?
The signifiers, 1x and 2x, refer to the front trays. With a 2x, or a 3x that also exists, there are multiple front chainrings, which multiply the number of gears available on the rear cassette. This means that if you have a 2x system, for example, there are two trays at the front and another piece at the sentence. To complete the sentence, you would say “two by twelve”, or the number of gears in the cassette, and you would refer to a bike with twenty-four gears in total in the case of 2×12. If it’s a 1x system, there’s only one chainring up front and all your gearing steps come from what’s available on the cassette.
To have two chainrings in the front, you also need a front derailleur. The front derailleur isn’t often mentioned in these discussions, but it’s an important part of the debate, because it’s impossible to have two chainrings without a way to switch between them, and that has implications for the design of a a bike and how it’s ridden.
Why do bikes traditionally use a 2x design?
Pure and simple, the benefit of a 2x design is that you get more speeds. It may seem obvious that more gears are better than less, but it’s not really the number of gears that matters. What is more important is the spacing between the gears.
Road bike gears were developed for racing, and that matters because they keep your desired speed and cadence within a somewhat narrow range, allowing for smoother shifting and avoiding the jerk you feel when your chain goes over a splits. The bikes are light, the speeds are high and efficiency is the most important thing. You need lots of gears spaced as close together as possible, so you can keep your cadence just right while the pack makes small gear adjustments.
Keep following this same thread and you can see how 2x solves the problem. There is an upper limit to the number of gear ratios available on a cassette. You could space these speeds out a lot, but the jumps would be confusing and it would be difficult to find an optimal speed. If you want enough reach to climb a hill, the best way to add it is to use a second chainring. It allows a bike to have small steps between gears but also an easier second set of gears for climbing.
What drove the move to a 1x design?
This description of 2x makes it technically superior and raises the obvious question why even consider 1x? The answer to this question is not as simple as why 2x makes sense. Getting to the bottom of it all starts with gravel cycling and the unique design challenges it entails. It’s also a story about the continued development of cycling technology.
We talked about it a bit in our discussion on the best gravel suspension forks, but the bottom line is that there is no easier way to make a more capable gravel bike than to up the tire size. However, when you start widening the tires, you run into packing problems. You need room for the front derailleur, tire, chainrings and cranks in roughly the same place. Mountain bikes solve the problems by having a wider crank and a longer bike, but gravel bikes are more compact, like road bikes. The groupsets used are based on road bike groupsets, and the desired geometry is pretty close to a road bike as well.
Early gravel bikes adopted a variety of tricks to solve this problem. Cannondale used an asymmetrical rear end called AI that moves the rear wheel hub to the drive side. Most metal bike frames, like the Litespeed Watia frame, simply flatten the drive side chainstay for a short distance. For carbon bikes, Gerard Vrooman came up with the revolutionary solution of dropping the chainstay on the Open UP bike and it has been widely copied since its release.
There is another solution though, and it’s much less complicated. Instead of solving the problem, just eliminate it and use only one tray. The chainring will be smaller, to have usable gearing, and there is no front derailleur to consider, so packing issues go away. Not only that, but without the need to move the chain smoothly between the chainrings, the tooth design can focus on preventing chain drop. You end up with a lighter bike because there are fewer parts, a safer chain over the big bumps, and a nice, short bike for a snappy feel. It’s an elegant solution but one that only works because of what gravel cycling used to be.
In the beginning, gravel cycling was all about exploration and adventure. Gravel racing was not what it is today and the needs of early gravel racers did not include maintaining cadence within an optimal range while riding at high speeds in a peloton. It was okay to have bigger jumps between gears as long as there was enough range.
What are the current design trends in gravel cycling?
Gravel cycling has changed a lot since the early days. More and more people are riding gravel bikes and the growing popularity has led to increased competition. Gravel racing has grown from a small part of a small market to a major force in the use and marketing of gravel bikes. There have also been significant advancements in the gearing choices available and this is a factor in the options you have and the choices you might want to make.
In those early days of exploring, there were road racing bikes and gravel bikes for exploring. Now the market has fractured into adventure gravel bikes and gravel race bikes. Gravel race bikes have moved closer and closer to road bikes and in this transition have taken on many of the same design features. For the purposes of our discussion, that means gravel race bikes almost always have a 2x gear. There has also been an increase in the mixed mountain bike category and these also tend to be 2x.
At the same time, adventure cycling has not disappeared. There are still plenty of people out there who don’t mind having bigger jumps in speed. Descending is no problem for this group and the packing benefits that 1x gearing brings have not changed. There is even less complexity in a 1x system and that appeals to those heading away from the grid. Along the way, there have also been other gearing introductions that fall between a mountain bike and a road bike. Smaller front chainrings paired with larger cassettes have opened up the choices available on both sides of the gravel riding spectrum.
Should you choose 1x or 2x for your next gravel bike?
By browsing our list of best gravel bikes, you will have to make the choice for yourself. How bikes are designed and marketed is one thing, but it doesn’t reflect everything you need to consider. If you’re looking for a bike to do double duty at the pointy end of gravel racing as well as road riding, then you’re going to want a 2x system. The additional gear choices mean you can maintain an optimal cadence in a group and you’ll also have the ability to climb. It’s a fairly simple choice for the most competitive riders.
For those more interested in exploring the rougher routes, then 1x is where you’ll want to look. One of the biggest advantages, which we haven’t touched on yet, is the simplicity of riding a 1x group. There are fewer components to break down and that’s a plus for off-road riding, but there’s also ease of shifting. Anytime you ride a 2x groupset you’ll want to avoid cross chaining (using both large rings or both small rings at the same time) and you’ll want to consider when you’re upsetting the bike frame with the big jump that comes from the displacement of the front trays. It’s easy to make these choices on relatively smooth ground. Things change off-road, however. When you go up a steep rocky trail there is a lot going on. You need to balance your weight front to back to maintain traction and find the best trajectory. Your focus is on the ride, not thinking about what gear you’re in and it’s much nicer to have a simple “easier or harder” shift decision.
Riding 1x on a gravel bike has many advantages but also has disadvantages. You’ll either have to sacrifice range or deal with big jumps between gears. Things are changing rapidly, however. SRAM XPLR, Campagnolo Ekar, and Rotor groups modify the equation with options for 1×12 and 1×13. There is even the option of going with a gear in the rear hub by adding the Classified system to your next bike. It is now possible to achieve incredible reach without sacrificing tight spacing, but there is still a cost drawback. If you have the budget available, you might find that you can get all the benefits of both 1x and 2x on the same bike.