The gravel bike market is growing each year; but with the recent Gravel World Championships being won on a road bike, we decided to take a look at whether you actually need a gravel bike to take on the rough stuff...
A gravel bike might look a lot like a road bike, but as we soon found out, there are some key differences which make them suited to very different types of riding.
The first key difference is the tyre clearance. While a modern disc-brake road bike like the Canyon Ultimate CF SLX 8 has space for what roadies would call a very wide 30-33mm road tyre, these seem rather small when compared to the massive 57mm tyres that Jamie can fit in his Lauf.
Larger volume tyres are run at much lower pressures and are therefore better able to deform over lumps and bumps. The immediate benefit to this is comfort, with the larger tyre absorbing far more energy and preventing you from being bounced around in the saddle as much as on a road bike.
This also plays a large part when it comes to speed over 'chunky' gravel, whereas a 30mm or so tyre might be able to keep up on well-kept fire roads. As the surface gets rockier, wider tyres are required to keep up speed and prevent riders from having to carefully choose lines.
As you get to a corner, you’ll find another benefit of the wider tyres, especially when you’re on a loose surface like gravel. The wider tyre offers a larger contact patch, and therefore has more to grip on to.
The Canyon Ultimate is a road race bike and as such, the geometry is designed to tuck you down into an efficient aerodynamic riding position. It is best described as long and low with steep head and seat tube angles, keeping the handling fun and fast.
A gravel bike, meanwhile, is designed for stability, and therefore gets a slacker head tube and seat tube angle along with a longer wheelbase. This puts the rider further behind the bottom bracket, aiding traction on loose climbs and helping to prevent getting thrown over the bars on technical descents. Obviously there is a limit to how much the bike can do, though!
You'll often find that gravel bikes are a little higher at the front end. This more relaxed riding position is often more comfortable on long rides and has less of an impetus on aerodynamics as gravel riding is usually at lower speeds.
And that leads us to one of the more dangerous aspects of a road bike on gravel. When trying to navigate a technical off-road climb, you often need to steer the bike quickly while pedalling. With their short wheelbases, road race bikes can suffer from a bit of toe overlap, which is where your toe strikes the front wheel. This doesn’t usually matter, as a road bike is rarely cornered at a slow-speed while pedalling.
A gravel bike, meanwhile, has a larger trail at the front wheel to eliminate any chance of toe overlap.
A gravel bike has a clear gearing difference compared to a road bike. Jamie’s Lauf uses a 1x setup with a wide-range cassette at the back. The Canyon, meanwhile, has a 2x chainring setup and a much closer cassette.
1x drivetrains are generally better in muddy conditions and allow for wider tyres to be used. A 2x setup reduces the jumps between gears, allowing road riders to maintain a more constant cadence at road riding speeds.
Jamie’s gravel bike is at the less adventurous end of the market, but even so, it still has more mounts than most road race bikes.
It features both a bottom bracket and top-tube mounting point to accompany the standard bottle cage mounts. Some gravel bikes can be adorned with more mounting points than you could shake a muddy stick at, and riders will often bolt all sorts of carriers and bags onto their bikes as they go off on multi-day adventures.
The Canyon, meanwhile, just has the standard bottle cage mounts. That's two in the main frame triangle, which is great for when you're being followed by a team car but not so great for getting lost in the wilderness with...
Each and every bike is, no matter the brand, tested for its specific purpose. In the case of a road bike, this normally means drops of around kerb height. This becomes a problem if taking it on gravel, as you could well come across terrain that requires you to ride off larger drops.
When this happens neither the bike manufacturer nor us, for that matter can guarantee that it won't break your bike, a typical gravel bike is therefore usually rated for larger drops and impacts.
These differences don’t necessarily stop a road bike from being ridden on gravel surfaces, but a road bike will be limited to well-graded and fine gravel due to the smaller tyre volume unless you, the rider, are very skilful.
A gravel bike’s larger tyres open it up to rougher terrain and the slacker geometry with reduced toe overlap. This makes it better for tight turns and technical climbs where the bike is being steered at slow speeds.
To answer the question of whether you need a gravel bike, you have to ask yourself where you’d be riding it as the terrain is the deciding factor, but for fine, well-graded gravel, you can get away with riding a road bike.
It's worth noting that if you're looking for one 'do-it-all' bike and like the idea of heading off-road, then it's probably a better idea to get a gravel bike. You can always put slick tyres on it!
Have you considered taking a road bike off-road? Let us know in the comments section below...