No matter where you ride, there's a bike just for you.
No matter where you ride, there's a bike just for you. (Photo: JJAG Media)

What the Hell Is a Gravel Bike?

More and more bike companies are selling road bikes built to be ridden on dirt roads. Are they marketing hype or the future of cycling?

No matter where you ride, there's a bike just for you.

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Along with disc brakes, the biggest buzz in road riding is around bikes built for a variety of terrain (dirt roads, singletrack, etc.), not just pavement. These drop-bar machines tend to have longer wheelbases than a normal road bike, more upright positions, lower bottom brackets for stability, and clearance for wider tires. They’re being promoted as gravel bikes, adventure bikes, all-road or all-terrain bikes, and a host of other names.

Marketing aside, if one thing can be said about this emerging segment of bikes, it’s that there are no hard-and-fast rules about what falls into the category. Road bikes have always existed on a continuum, from light, fast, aggressive race models to longer, stabler touring machines. The gravel movement has a similar scale. Cross-bikes have been around forever, too, and though they generally have quicker steering and are oriented more toward short, fast, aggressive efforts, comparing geometry numbers shows that the differences between them and adventure roadies are blurry. Like mountain bikes, there’s even debate over wheel size, with several brands opting for 650B (and the additional tire clearance it affords) over 700c. All of which is to say: the adventure road category encompasses everything from a skinny-tired steel touring bike, like the Breezer Inversion Team, all the way up to a monster cross machine like the Rawland Ulv, with three-inch tires on 26-inch rims.

So how is a consumer to make sense of it all? Do we need all this variety? And are these bikes even that useful or fun to ride?

We had so many bikes (14) in the adventure road category at this year’s Outside test that we dedicated an entire day to dirt road testing. Several of our more traditional road bikes also had tire clearance and other features to keep pace on dirt. I’ve been plugged into this scene for a while, having raced events like the Dirty Kanza and done quite a lot of dirt road bikepacking, but for many testers, it was their first or second experience riding drop bars on dirt, and feedback was all over the map. Some people loved the excitement and challenge of smashing along on skinnier tires on dirt. Others found it tough going and hard on the body, and they wondered why you wouldn’t just ride a hardtail mountain bike.

I put that question to Dave Koesel, general manager at 3T America, which produced one of the favorite roadies of our test, the 3T Exploro. “If you primarily ride smooth trails and fire roads and don’t care about the speed, a hardtail may be a good choice. But for riding gravel at speed, a road-oriented position offers huge savings,” says Koesel. “A mountain bike position has somewhere in the neighborhood of 5,000 grams of drag, a good road position has 3,500 grams, and a good [time trial] position has 2,500 grams. In the same way that you are faster on a TT bike than a road bike, you will be faster on a drop-bar bike on gravel than you would be in a wide-bar upright position of a typical mountain bike. It’s free speed.”

Nonetheless, the offerings in the drop-bar category are still all over the place. To give you a sense for just how broad the category truly is, here’s a short list of some initial tester favorites.

Lynskey GR 250 (From $2,960)

Of the gravel bikes we tried, this is probably the exemplar of the category, with a rough-taming titanium frame, fairly long chainstays (435mm), a slack head angle (70.5 degrees), and slightly knobby 42mm tires on 700c wheels. (There’s an option for 650B wheels with 2.1-inch tires, which might be good for loaded touring, but we felt the bigger wheels were plenty for everyday use.) The carbon fork is pretty much mandatory as it helps take the hard edge off road vibration. Unlike most gravel bikes, the GR 250 doesn’t come with a flared handlebar, which can add hand positions, stability, and control on loose, rugged surfaces. Testers, however, exclaimed over the bike’s balanced and comfortable feel. It feels like a nice, comfortable midpoint between a roadie and a mountain bike: fast and explosive yet stable and at ease in the dirt.

3T Exploro (From $3,000 for the Frameset)

This hybrid, billed as the world’s first aero gravel bike, was probably the most sought-after ride on the dirt road day. The biggest difference between the Exploro and its cousin, the Open U.P., is this bike’s chunky, aerodynamic tubing, which might seem strange for dirt road riding. But it actually makes sense if you consider that gravel races often entail lots of solo time in the wind. Our tester was equipped with 3T DiscusPlus 650B wheels mounted with 47mm WTB Horizon tires, a combination that’s the best of both worlds: the slicks are fast, but the width is still cushy for dirt. The Exploro illustrates the weird and cool nexus of ideas in this realm at the moment, as it’s both extremely racy (with super-tight chainstays and a short head tube) and wildly capable courtesy of all that tire clearance (room for up to 2.1 inches). And at just 17.4 pounds (less with skinny rubber), it’s still perfectly capable in a peloton.

BMC Roadmachine (From $2,000)

This is the Swiss company’s endurance road machine, and not a gravel bike at all, but it illustrates the continuum in this category. Our top-shelf model from the test is a full road racer with Dura Ace Di2, DT Swiss RC38 carbon wheels, 25mm tires, and a hang weight of just 16.4 pounds. It also has the hallmarks of all-road machines, however, including thru-axles front and rear, hydraulic disc brakes, lots of vertical compliance built into the frame, and tons of tire clearance. I’ve ridden it with up to 35mm rubber, and you might even be able to squeeze in skinny 38s. All of this means that, like the Trek Domane SLR Disc, the Roadmachine, with its preference for pavement but the ability to easily go beyond, is one of the most versatile road bikes out there.

Moots Baxter 29 (From $4,330 for the Frameset)

On the other end of the scale from the Roadmachine is the Baxter 29. Even by its nomenclature—29 inches versus 700c—this bike leans toward the dirt side of the equation, and we would even go as far as calling it a drop-bar mountain bike. It has mountain components (XT Di2 in our case), a carbon fiber Enve fork to complement the already buttery titanium-frame ride quality, and low-profile 2.25-inch tires. The Salsa Woodchipper handlebars are wildly flared for excellent off-road manners, and overall the bike is upright and incredibly stable on dirt. It’s made for dirt road touring and events like the Tour Divide, and while you could ride it on the pavement just fine with a pair of slicks, it would look and feel a bit strange in a group of roadies.

All that variety may seem bewildering, but that’s part of what I like about this category of bike. Whether you’re a strict roadie, a tourer who mixes it up on dirt and pavement, or a mountain biker getting into bikepacking, the category has something for everyone. And who doesn’t want more versatility? Something like the Exploro, for example, (or the Diamondback Haanjo, or the Trek Domane SLR Disc) can stand in for both my road-racing machine as well as my dirt-road adventurer. That’s two bikes for the price of one and little compromise at either extreme.

What’s not to like about that?

My advice: Don’t get caught up in labels. Instead, look at the bike’s features and compare them to the type of riding you predominantly do. There’s a bike for almost every niche, and most are also capable and versatile enough to freelance in a variety of other conditions.