For years, gravel racers have looked to mountain bike tyres for speed on rough terrain. But what if suspension is the real key to going fast?
Two recent four-day testing blocks conducted by Marc Graveline, a performance engineer best known for co-developing the Notio Konect aero sensor and consulting for WorldTour teams on aero and tyre testing, using his in-house drag measurement system, IMUs (Inertial Measurement Unit, which track acceleration and angular velocity) and Unbound-bound pro racer Hannah Shell, turned a belief that big, fat, mountain bike tyres are fastest on rough gravel on its head.
Gravel racing has always sat in the grey area between road and mountain biking. And lately, a growing number of riders have been leaning toward the MTB end of the spectrum, fitting mountain bike tyres for improved speed, comfort and control on chunky terrain. Testing has shown that these big tyres are faster. But Graveline's testing adds a large caveat to that idea.
The big revelation? On the rough gravel roads, mountain bike tyres were only faster than narrow tires when paired with a rigid fork. Once a suspension fork was introduced, gravel tyres flipped the script, outperforming not only the gravel tyres paired with a rigid fork, but also MTB options. The improvements came in both feel and in considerable, measurable wattage savings.
The results further our understanding of what goes fast on gravel, building on the work of pros (turned tyre science enthusiasts) like Dylan Johnson and Alex Howes, who have helped popularize significantly wider tires in gravel racing.
Speaking on this week’s Performance Process podcast, one of Escape Collective's members-only pods, Graveline shared the surprising findings from two testing blocks designed to optimise every aspect of Shell’s Unbound setup.
“It really shocked me,” he said. “We ran both tyre types on both fork setups, and the performance reversed completely when we added suspension. The gravel tyre became faster. That was the moment the penny dropped, every component interacts with the others on gravel in ways we didn’t fully appreciate before.”
Structured testing for chaotic terrain
Graveline utilised a structured, repeatable testing method combining real-world field protocols, drag sensors, and IMUs to isolate the effects of tyres, pressure, and suspension on gravel performance. The protocol is similar to that which Escape Collective has been developing with John Buckley of Streamlines Aero and seemingly similar to testing done by Dan Bigham at this year’s Paris-Roubaix.
To (overly) simplify the concept, think of it like breaking down a complex equation. Multiple variables, including aerodynamic drag, rolling resistance, drivetrain losses, and vibration losses, shape cycling performance. By directly measuring power, speed, and wind conditions using sensors and structured testing, you can calculate these variables and compare setups to determine which one actually yields the faster results.
The findings emerged from two four-day blocks of highly structured testing, tailored to Shell’s upcoming Unbound Gravel race. Graveline, a veteran of road and triathlon aero optimisation who was part of the team that delivered the Notio Konect, the first so-called aero-meter, and has more recently worked with several World Tour teams running aero and tyre testing, approached gravel with the same level of rigour.
Each trip started with a full day of aero testing on smooth roads using road tyres to isolate baseline drag figures. The remaining days focused on tyres, pressures, surface mapping, and eventually suspension fork dynamics.
Trip one focused largely on understanding how tyre pressure and compound impacted rolling resistance across different gravel surfaces. By the second session, that testing evolved. One day was allocated solely to tuning and understanding the role of the suspension fork. Another day re-tested tyre setups, now with forks added into the equation. The final day consolidated and validated the findings, evaluating the full system in race-like conditions.
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