This was a piece one of our mechanics, Tom, put together for a mate. We thought it worth posting here.
At first glance, adventure bikes (a.k.a. gravel bikes) can appear very similar to touring bikes. They both have drop handlebars and wider tyres than road bikes. On closer inspection though, they have some significant differences that should be considered by a potential buyer. The most important of these are gearing, geometry and portage capabilities. Our technically astute mechanic, Tom, takes you through the details.
Most “off the shelf” adventure bikes come with road bike gearing. Traditionally, road bike gearing is designed to allow relatively fit riders to ride on smooth, paved roads with little or no additional luggage. This meant you could only comfortably travel down to speeds of around 12km/h. Recent pushes by professional riders to use lower gears and race organisers to include steeper roads has lead to lower road gearing, down to around 9km/h. This is great news for adventure bike riders, and most adventure bikes will come with these lowest possible road gearing ratios.
However, if you’re riding up a long, steep, unpaved climb with bulging panniers and a tent strapped on, it’s likely you’ll want to go even slower. By using mountain bike gearing, most touring bikes can be easily ridden down to speeds of around 6km/hr. Much slower than this, and you’ll probably start losing your balance.
If you’re unsure what kind of gearing you need, ask yourself the following questions:
Am I likely to do many long, steep climbs on my bike?
Is there any chance the climbs will be unpaved?
Am I likely to be carrying large loads on the bike, including things like tents, stoves and supplies for multiple days?
Do I like to climb comfortably rather than climb at my limit?
If you answered no to at least two of these questions, then you’ll probably be fine with road gearing. In this case, the world is your oyster, and you have a gamut of options open to you, including integrated brake/shift levers, hydraulic brakes and SRAM’s single chainring options.
If you answer yes to at least three of these, you would likely do well with lower mountain bike gearing. Unfortunately, component manufacturers separated their road and mountain design departments a couple of decades ago, so most of their 10 and 11 speed groupsets are not cross-compatible. This means that your modern integrated drop-bar shifters will not work with a mountain-bike derailleurs, which is one of the reasons
you generally don’t see them on heavy duty touring bikes.
Drop-bar touring bikes often achieve lower gearing by using older 9 speed components, or by using third party shifters such as the ‘Microshift’ levers seen on the 10 speed Surly Disc Trucker. Another way around it is to install a ‘shift multiplier,’ such as the Woolftooth Tanpan, which adjusts the pull ratio of the shifter to match the derailleur. They work remarkably well, as demonstrated by our staff member Oli, who just rode half-way across the world on a Soma Wolverine with just this kind of setup.
If money is no restriction, you may even consider using Shimano’s electronic gearing systems, which are compatible between road and mountain groupsets. If your eyes are glazing over, don’t worry, you can always come in store or call us up and one of our staff members can walk you through it.
A couple of centimeters make a huge difference to the handling of a bike. The rear wheel on a touring bike is generally placed a few centimetres further back than on adventure bike. This creates more space for tyres and mudguards, and more clearance between your feet and your panniers. This is important, not just to keep you dry, but also to keep you comfortable. Tyre pressure and width is by far the single biggest factor affecting vibration dampening on a bike, and a wider tyre will help to smooth out a choppy road surface. Wider tyres also provide extra grip, which is reassuring on those steep gravel descents.
The downside to wide tyres is the added weight and rolling resistance. Most adventure bikes can fit tyres around 37mm wide (32mm with mudguards). You can go even wider if you change to the slightly smaller 650B wheel size, but this is an expensive exercise. Most touring bikes can fit 42mm tyres with mudguards and room to spare.
Moving the back wheel back also affects the handling, creating more stable and predictable cornering, particularly under a heavy load. In contrast, moving the rear wheel further forward results in a more lively feeling. These handling changes are best understood by riding the bikes, which you can do any time for free by heading down to Velo.
It probably comes as no surprise that touring bikes are designed to carry a lot of gear. Disc brake equipped touring bikes generally mount their calipers inside the rear triangle. This allows the rack to be fitted without having to extend around the caliper, strengthening the rack significantly. This design, however, results in a poor cable route that collects water and grime. This often emerges as a rubbing disc rotor, a very annoying noise to hear at the start of a long cycle tour. Cable replacement is relatively inexpensive at around $40 including labour and is usually required every few years. Hydraulic disc brakes render this problem irrelevant, but are quite expensive for drop bars, and don’t come specif
ied on many “off the shelf” bikes. The forks on touring bikes are generally designed to carry larger weights and have more mounts for front racks, which allow for front pannier bags.
Adventure bikes generally prioritise performance over carrying capacity. They often mount the brake caliper for cleanliness in muddy conditions, rather than for pannier strength. They are, however, perfectly suited for bike packing, which does away with racks and panniers and utilises
bags attached to the handlebars, saddle and frame. This both reduces weight and improves aerodynamics, though the bags are a little more difficult access, and are less spacious than a four pannier setup. Check out the picture at the top of this post for an illustration of these contrasting styles. Adventure bikes are often built a little lighter than touring bikes. While this makes them more fun to ride, their wheels often have a few less spokes than those on touring bikes, making them more prone to broken spokes under heavy load.
If you are unsure what portage requirements you have, consider the following questions:
Do I need to carry significant amounts of equipment, such as stoves and food?
Am I a heavier rider?
Will I be travelling loaded on rough roads which are tough on racks and wheels?
Do I like having easy access to all my stuff at the end of the day?
Relax. Both style of bike are wonderfully versatile bikes. A touring bike will make an adequate gravel grinder or commuter, and plenty of rugged touring has been done on a gravel bike. Change your mind, and both these classic, versatile bikes should hold their resale value fairly well. Or you could always get one of each!