Do you need a gravel bike to ride gravel roads? Of course not. One of the most appealing things about gravel riding is the lack of hard-and-fast rules. Your endurance road bike or cyclocross bike can easily be transformed into a gravel-capable machine with nothing more than good tires and a sense of adventure.
Gravel bikes have become popular because they address the specific needs of off-pavement riding. Compared to road bikes and cyclocross bikes, gravel bikes offer better comfort and stability. They have more relaxed geometry and much more tire clearance. These features enhance the experience of riding dirt, trails, gravel, logging roads, and everything in between.
But what about the original off-road machine? Long before the gravel trend, people were already riding mountain bikes on dirt and gravel roads. And though gravel bikes look a lot like road bikes, most of the technology they use — such as tubeless tires, disc brakes, and clutch derailleurs — was adapted from mountain bikes.
When looking for a new bike, some riders may find themselves torn between choosing a gravel bike and a fast XC mountain bike like a 29er hardtail. Both are good options for exploring mixed terrain from gravel roads to light singletrack trails. But which is better for you?
I have experimented with both gravel bikes and hardtail 29er mountain bikes. I rode them for everything from commutes to fast gravel group rides and races. So, let’s help you choose the right bike by comparing the technical differences between gravel bikes and mountain bikes and the advantages and disadvantages of each.
If you needed to pick one physical trait to separate gravel bikes from mountain bikes, the handlebars are most obvious. Gravel bikes are equipped with drop handlebars while mountain bikes use flat handlebars.
Though it is possible to quibble with this distinction — flat bar gravel bikes and drop-bar mountain bikes are rare but they do exist — it serves as a very reliable indicator of a bike’s intentions.
Gravel bikes use drop handlebars because they are normally ridden at higher speeds on smoother roads over longer distances. Drop handlebars are standard equipment on road and cyclocross bikes because they provide more hand positions than flat handlebars. The ability to adjust your hands improves comfort and reduces fatigue on long days in the saddle. The drops also provide a more aerodynamic position and leverage for sprinting. Drop bars give gravel bikes versatility for riding at high speeds, as they are meant to transition easily between paved and gravel roads. These bars are also usually narrower, making them better for riding shoulder-to-shoulder with other riders during group rides and races.
Mountain bikes use flat handlebars because they provide more control in off-road terrain. Flat bars are wider than drop bars and provide stability and leverage. On rough and technical singletrack trails, they make it easier for riders to maneuver and hang on to their bikes. Flat handlebars often position the rider more upright with their hands further apart. This can be more comfortable, but it makes you less aerodynamic when riding at higher speeds on smooth, open roads. Flat bars are best for the slower speeds encountered on singletrack trails.
Tire clearance is the biggest difference between gravel bikes and more traditional road and cyclocross bikes. Gravel bikes can fit wider tires, generally in the 38-45mm range. A few models are now capable of fitting up to 50mm tires. Wide tires are good for gravel riding because the increased tire volume allows for lower tire pressures to improve comfort and traction.
The largest gravel tires available are still narrower than most mountain bike tires. The majority of XC mountain bikes are designed to fit tires in the range of 2.1-2.4” wide (for reference, 50mm gravel tires measure about 1.97”). Mountain bike tires will have more weight and rolling resistance but offer better comfort and traction.
Like the handlebar comparison, gravel bike tires have an advantage on faster, smoother terrain, while mountain bike tires can handle rough roads and trails.
Suspension takes the edge off of the bumps and it will increase off-road comfort and control. Most mountain bikes have at least a suspension fork, but the majority of gravel bikes use rigid designs.
The downsides of gravel riding with suspension are the additional weight and loss of efficiency. Regular mountain bike suspension forks can add two to three pounds over a rigid carbon fork. Suspension travel also decreases efficiency because a small amount of pedaling power is lost to vertical motion (bobbing) instead of providing propulsion.
Both gravel and mountain suspension can usually be locked out to maximize efficiency when needed.
The Lauf Grit SL gravel suspension fork.
There are a few gravel bike models that utilize suspension, but they are rare. Many riders who desire suspension for their gravel bike will need to purchase aftermarket suspension forks. Notable examples of gravel-specific suspension forks are the Lauf Grit fork, FOX AX fork, and MRP Baxter fork. These forks provide significantly less travel than mountain bike forks — 30mm for the Lauf and 40mm for the FOX and MRP forks Cannondale’s now-discontinued Slate gravel bike featured a 30mm-travel Lefty fork.
This small amount of travel can smoothe out bumps and chatter on rough gravel roads and mellow trails while remaining efficient enough for smooth gravel and paved roads. But if you're used to the plush comfort of a mountain bike fork, you will find them to be pretty firm.
As a broad generalization, gravel bikes will have “harder” gearing which will allow riders to continue pedaling when riding at higher speeds. Mountain bikes will have relatively “easier” gearing that suits steep and technical off-road climbs.
Thanks to modern cassettes, both options have relatively wide gear ranges — that is the difference between the easiest and hardest gears. However, that range can only go so far. That means that both gravel and mountain bikes have limitations when it comes to gearing.
Take, for example, a gravel bike and a mountain bike each equipped with a SRAM 1x drivetrain. Gravel bikes with a Force 1 gravel drivetrain will commonly use a 42t chainring and a 10-42t cassette.
Mountain bikes with an X01 Eagle drivetrain usually use a 32t chainring and a 10-50t cassette.
Both have pretty wide gear ranges. However, the hardest gear combinations provided by the drivetrains are very different: 42t-10t and 32t-10t, respectively. Because the gravel bike is able to fit a much larger (42t) chainring, you are less likely to “spin out” or run out of gears when pedaling at high speeds (e.g., above 25-30mph).
The easiest gear combinations are 42t-42t and 32t-50t respectively. Because the mountain bike provides a substantially lower gear, it will be much easier to pedal up difficult climbs.
Gravel drivetrains are geared for mixed terrain to allow riders to easily transition between slower off-road riding and faster pavement riding. Double-chainring gravel drivetrains further increase a gravel bike’s top-end gearing. They will generally have a larger chainring than what is used for a 1x set-up, while still providing a small chainring for climbing. This is desirable for most gravel riders who need a wider gear range for climbing and fast group rides or races. (To learn more about the differences between gravel drivetrains, read our in-depth 1x vs. 2x article.)
Mountain bike gearing might be more desirable for gravel riders who need an easier gear for hard climbing, riding while loaded with heavy bike-packing gear, or riders riding slower and more technical gravel and singletrack trails.
Gravel bikes can be converted to use a mountain bike drivetrain (e.g., SRAM AXS allows for a “mullet” set-up using the 10-50t mountain cassette). But most mountain bikes don’t have enough clearance to fit the larger chainrings of gravel bike drivetrains and top-end speed will always be limited compared to gravel bikes.
So, the choice between the gravel gearing and the mountain bike gearing boils down to whether you anticipate your riding to be at generally higher speeds, or if you plan to grind up steep climbs. Or, if you are more or less fit, that could influence your gearing preferences,
Compared to road or cyclocross bikes, gravel bikes place riders in a more upright, endurance-oriented position for better stability, control, and comfort when riding off-road. The wheelbase and chainstays will be slightly longer, the bottom bracket lower, and the stack higher. The head tube angle may also be slightly slacker to further improve stability.
Gravel bikes can be considered a middle ground between road bikes and mountain bikes. Mountain bike geometry is even more upright and emphasizes stability and control. They will often have more stack and slacker head tubes. Mountain bikes won’t feel as quick-handling on pavement or smooth gravel compared to a gravel bike, but the increased stability is better for extremely rough gravel and singletrack trails.
Fit and comfort
Comfort is subjective, and it’s possible to make any type of bike fit more or less comfortably by changing or adjusting the fit with the handlebars, stem, and saddle. Gravel bikes are already designed to provide a fairly comfortable riding position, but if you have severe flexibility limitations or other comfort issues that a gravel bike can’t accommodate, a mountain bike that provides an even more upright position is a good option.
On gravel roads, the majority of riding comfort will come from the tires. Larger tires have more air volume, and can be run at lower pressure to absorb bumps and vibrations. Gravel tires in the 38-45mm range will be fine for typical gravel roads. If you’re riding a lot of extremely rough gravel (e.g., gravel with loose-golf-ball- to baseball-sized stones, deep ruts, roots, and large embedded rocks) or trails, you may benefit from the larger tires and additional suspension offered by mountain bikes.
Confidence and capability
Gravel bikes are capable enough to be ridden quickly by skilled riders on easier singletrack trails. They ultimately won’t be as fast as a mountain bike, but you may be surprised by how much technical terrain you can successfully ride. If you like an exciting challenge and have experience riding cyclocross or mountain bikes, riding a gravel bike on singletrack trails can be lots of fun.
If you’re not as comfortable on dirt or regularly riding singletrack trails, mountain bikes are the better option. The combination of flat handlebars, suspension, wider tires, and mountain bike geometry gives riders maximum stability, traction, and control. That's great for pushing the limit or getting comfortable venturing away from the pavement.
Even if you aren’t riding difficult terrain, a mountain bike could help you ride faster if you struggle with confidence when cornering, braking, or descending on gravel roads. (If you’d like tips specifically about how to corner, brake, and descend on gravel, read our Guide to Riding Gravel.)
Efficiency and speed
On smoother surfaces, whether paved or gravel, a gravel bike will be much faster and more efficient than a mountain bike. As mentioned earlier, the drop bars offer a more aerodynamic profile, the narrower tires have less rolling resistance, and the harder gearing is better for high speeds.
Fitness is an important factor, but it will always be much easier to keep up with a fast gravel group ride while on a gravel bike. If the terrain is smoother and flat, rolling, or downhill, a gravel bike will get up to speed and maintain speed more easily.
On very steep, slow climbs, however, a mountain bike is not a huge disadvantage. Mountain bikes will, of course, be faster than gravel bikes on true mountain bike terrain like technical singletrack trails.
Weight is also a consideration. Gravel bikes often weigh less than comparable mountain bikes (i.e., same frame material at the same price point). That is because larger tires and suspension add to a mountain bike’s overall weight.
How to choose
What is your local riding terrain like? What type of roads or trails do you ride regularly? This is the biggest factor in determining what type of bike to choose. Let’s say you mostly ride from your house to explore dirt and gravel roads at the edge of town. You might have to ride several miles of paved roads through town before you get out to the good stuff. In this case, a gravel bike that balances efficiency on the pavement with fun on the gravel would be ideal.
If you dream about wandering as far from the pavement as possible onto poorly maintained Jeep roads or rocky and rooty singletrack, then a cross-country mountain bike might be better even though it’s less efficient and fast on the road. It will allow you to ride more comfortably and explore more on the worst terrain you will encounter.
Beyond your terrain, goal events might influence your decision. Is your dream to finish the Dirty Kanza 200 gravel race or something similar? If you want to ride hard in a group of riders, race competitively, or just go fast and set new personal bests, then a more efficient race-focused gravel bike will be more desirable. On the other hand, if your friends might talk you into off-road races like the Epic Rides series or Leadville Trail 100, a mountain bike is the more versatile setup.
Who has the better bike in this situation?
Choosing the right bike can sometimes be agonizing. I’ve made those tough decisions over the past few years. I’ve been on plenty of rides where both gravel bikes and mountain bikes were present, and I've experimented with different gravel bikes and even a hardtail 29er mountain bike.
For most of 2017-2018, I rode a cyclocross bike converted to a gravel bike (read my bike write up for my Focus Mares CX). On this bike, I participated in several gravel group rides and races. I achieved a top-10 finish in the Dirty Kanza 100. It was fast, responsive, and racy feeling. I still took this bike onto some local mountain bike trails that tested the bike's limits. I didn’t ride these trails fast — mostly I just survived. But it was good fun.
In late 2018, I began fantasizing about doing gravel rides that would explore more rugged trails. I switched to a hardtail 29er that I equipped with a rigid carbon fork. The fork reduced the overall weight significantly and improved pedaling efficiency. The flat bars and large 2.25” tires still made it incredibly confidence-inspiring.
This bike allowed me to continue participating in gravel group rides. Whenever we dropped into a section of singletrack or encountered snow, I would leave most riders on gravel bikes behind. This bike was extremely fun, capable, and versatile. I likely could have ridden it forever and have been very happy.
But over time, my goals shifted toward organized competition, and the 29er hardtail simply couldn’t keep up. Because the bike's top speed was limited by aerodynamics and mountain bike gearing, I found myself regularly spun out and getting dropped when speeds started entering the high-20s.
For 2020, I’ve returned to a faster and more efficient gravel bike set-up with a Lynskey titanium gravel bike. I plan to race the Dirty Kanza 200 this year, and I want every advantage possible. In my case, I had to choose a bike that better suited my ambition.
Gravel riding is still evolving. And I'm always evolving as a rider. Whatever bike I'm on, the most important thing is that it can put a smile on my face. The only gravel "rule" you should worry about is having fun.
For the foreseeable future, I will stick with a fast drop-bar gravel bike. But that could change and you might find me riding a hardtail mountain bike once again.
Have you used a mountain bike for gravel riding or a gravel bike on mountain bike trails? What bike do you choose and why? Let us know in the comments!