Do you want to go fast, or do you want to go everywhere? Some cycling segments look very familiar to the average rider or casual observer if you park two bikes representing each, next to each other. Only dedicated mountain bikers could tell the difference if you put a downcountry and trail bike next to each other. But it’s different with road and gravel bikes, which might have similar silhouettes but are very different in many ways.
Although road and gravel bikes have drop handlebars and look similar, they feature many points of difference, accounting for components specifically tailored for each purpose.
Frame design and geometry
Road bikes are designed to be the most efficient bikes you can ride because, at speed, aerodynamics are the most significant issue influencing efficiency and performance. That’s one of the reasons why road bikes are traditionally much shorter, for a specific size than a mountain or gravel bike. When competing in a tightly bunched group, the shorter overall size allows better drafting of other riders and less crashing risk.
Road bike geometry prioritises climbing efficiency and overall power transfer, with secondary considerations for comfort and fluid handling on rougher roads. Steep head and seat tube angles are standard on road bikes, allowing riders to remain in the most powerful position when climbing. Those steep angles can also make a road bike feel more ‘nervous’ and ‘twitchy’ at speed, which can become intimidating for less confident riders on a high-speed descent when an asphalt road surface is less than perfect.
2023 Argon 18 Dark Matter gravel bike.jpg hero, by Suvi loponen
Gravel bike geometry is longer and slacker than on road bikes. The additional length creates more stability, while a slackened head angle slows down the steering, making it more predictable and confident on loose surfaces, like corrugated dirt road descents or some singletrack.
Beyond the geometry differences between road and gravel bikes, the frame designs also prioritise different properties for their tubing. Whether you are riding an aluminium, carbon-fibre or steel version of either, the road bike will always have slimmer, lighter tube sections to reduce weight compared to a gravel frame. Because a gravel bike rolls most of its mileage off-road, having to absorb the punishment of corrugated dirt roads and singletrack trails, it requires a more robust, heavier tube profile to ensure durability.
Wheels and tyres
2023 Argon 18 Dark Matter gravel bike-24.jpg, by Suvi loponen
The principles of aerodynamics, efficiency and durability play an even more distinct role in the differences between road and gravel bike wheels and tyres.
Deep-section carbon wheels look cool and reduce aerodynamic drag by lessening spoke turbulence. But for all the aerodynamic gains those deep section wheels bring, they also create risk. A deep section rim has sail-like properties in any crosswind riding conditions, and having your steering controlled by the elements doesn’t make for a great ride as those who frequently ride in blustery coastal conditions will attest.
Deep-section carbon wheels and wind gust influence are less of an issue for gravel bikes. Why? That surprise deflection you might experience because of a gust deflecting your wheels won’t necessarily push you into the driving lane of approaching traffic on a quiet dirt road.
2023-vitus-venon-evo-sram-force-riding-1.jpg, by Suvi Loponen
The biggest difference in rim choice between a road and gravel bike is not its profile, but the internal diameter. Road bikes have much narrower rims than gravel bikes because they run smaller tyres. Although road bike tyre widths have increased from a broad average of 23c to 28c, they are still much narrower than the average gravel bike tyre in the 38c to 47c range.
Gravel bike tyres need to be larger, with more layers of material to enhance puncture proofing, and hold more air volume, potentially increasing ride comfort and grip when rolling over rough roads at an appropriate inflation pressure. The diversity of tread patterns and skid depths with a road tyre is much less than with gravel bike tyres, which have to function in many applications – from dusty desert conditions to muddy trails.
Road and gravel bikes both feature drop handlebars, but if you viewed the two front-on, there’s a noticeable difference in width and flare.
Again, aerodynamics and group riding dynamics are the primary issues with road bike handlebar design. Narrow handlebars allow road riders to bunch much closer, creating opportunities for aerodynamic gains in a group. If you ride a road bike solo, the narrower handlebar slims your frontal aero when tucking into an aero position, reducing drag.
For gravel bikes, the handlebar is more about steering leverage and control than aerodynamics or positioning in a group. That’s why gravel bikes feature such radical-looking drop handlebars, which are much wider than those on road bikes and have extensive flaring at the ends.
2023 Specialized Creo 2 launch riding-3.jpg, by Specialized
The wider your drop handlebars are, the greater their steering leverage, meaning you can keep better control when riding a rocky, loose dirt road descent or flowing through a forest singletrack trail. But what about the flared shape? Hand fatigue is a real issue during that gravel adventure tour when riding for days on end over corrugated roads. Drop handlebars with the ideal width and flare blend can position the wrists to reduce fatigue.
SRAM Apex Eagle rear derailleur and cassette, by SRAM
Road bike drivetrains are beautiful, almost delicate, in their appearance. With such exact tolerances, road bike gearing shifts crisply, allowing riders to keep their ideal cadence, even when there is a sudden change in gradient or headwind.
Engineers responsible for road bike drivetrains prioritise lightness and shifting crispness, knowing that environmental contaminants aren’t much of an issue. This allows for ultra-lightweight designs and tiny mechanical tolerances, delivering responsive and rapid shifting. For gravel bikes, the needs are different.
Once you add dust, mud, and all manner of other environmental contaminates to the riding equation, drivetrain requirements change. Shifting crispness and lightness need to be balanced with the need for durability and robustness. A gravel bike drivetrain must resist the punishment of fine dust packing onto it during a summer adventure ride in Spain, or being caked with mud when riding through the average British winter.
It’s the reason why gravel bike drivetrains are slightly heavier and closer to those of mountain bikes, compared to road bikes. Durability matters more than specific gearing steps and outright speed, which are the higher principles for a road bike rider.
Suspension is where there are remarkable differences between road and gravel bikes. Although elastomer damping has been present on very few road bikes, it’s more prevalent in gravel bike design. Elastomer frame inserts, primarily found in the rear triangle bridge or seatstay joint, help to reduce rider fatigue on rough roads.
Some designs even balance the ‘softtail’ elastomer feature with an ultra short-travel suspension fork, for riders planning to navigate the most adventurous and roughes gravel bike routes. Although a gravel bike fork adds some maintenance factor, it’s a more natural feeling design than a headshock under the handlebar or a suspension stem.
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