For years, gravel riders seeking speed on bumpy trails thought bigger, mountain bike-style tires were the answer. The logic seemed simple: fatter tires offer more grip and comfort on rough stuff. But new testing throws a fascinating curveball, suggesting that the real speed secret on challenging gravel might actually be… suspension.
Contents
Forget everything you thought you knew about tire size for fast gravel. A recent deep-dive test found that once a suspension fork is added to a gravel bike, narrower gravel-specific tires can actually be faster than wider mountain bike options on rough terrain. This isn’t just a feeling; it translated into significant, measurable energy savings. The key takeaway? Your fork choice dramatically changes the tire game.
The Old Wisdom vs. The New Finding
The world of gravel riding sits right between road cycling and mountain biking. As courses get rougher, many riders have leaned into the mountain bike side, choosing wider tires for better traction and control. Testing in the past has shown that wider tires can be faster, particularly on rigid bikes where they help absorb bumps that would otherwise slow you down.
However, performance engineer Marc Graveline, known for his work in cycling aerodynamics and tire testing, conducted extensive tests with pro gravel racer Hannah Shell. Their goal was to optimize Shell’s setup for the notoriously tough Unbound Gravel race. What they discovered completely reversed the script:
On the same rough gravel surfaces, while wide mountain bike tires were faster than narrower gravel tires on a rigid fork, the moment a suspension fork was introduced, the gravel tires pulled ahead.
“It really shocked me,” Graveline shared. “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.”
This highlights how complex bike performance is. It’s not just about one part, but how all the parts work together.
How They Figured It Out
This wasn’t just a simple ride-and-see test. Graveline used a rigorous, data-driven approach typically seen in pro road racing and triathlon. His method involved:
- Structured Field Testing: Riding specific sections repeatedly to get reliable data.
- Drag Sensors: Measuring aerodynamic drag (how much the air slows you down).
- IMUs (Inertial Measurement Units): These are like sophisticated motion sensors that track movement, acceleration, and vibration – crucial for understanding how the bike interacts with bumpy surfaces.
By measuring speed, power output, and bike movement simultaneously, they could isolate how different components, like tires and forks, affected overall performance and efficiency. The testing involved several days, first establishing baseline data on smooth roads, then moving to rough gravel to analyze tire pressure, compound, and finally, the impact of the suspension fork.
The Bike That Broke the Mold
The specific setup that tested fastest for Hannah Shell’s Unbound race featured a suspension fork paired with what might seem like surprisingly narrower gravel tires: a 45mm in the front and a 40mm in the rear. This combination directly challenged the widespread belief that you needed the widest possible tire on rough gravel, especially with suspension.
Hannah Shell's Cervelo Aspero gravel bike setup for Unbound, featuring a suspension fork and faster-rolling 45mm/40mm gravel tires.
Why might this happen? While wider tires can feel more comfortable by absorbing impacts, they might also lose energy by deforming more or causing excess suspension movement on certain terrain. A suspension fork handles the big bumps, allowing a slightly narrower, potentially faster-rolling tire to maintain momentum with less energy loss on the ground and less vibration transferred to the rider and bike.
What This Means for Your Ride
This testing offers a valuable insight for anyone riding gravel, especially on rougher terrain or considering adding suspension.
- It’s a System: Don’t just think about your tires or your fork in isolation. How they work together is critical.
- Suspension Changes Tire Choice: If you have or are planning to get a suspension fork, you might find that you don’t need the absolute widest tire to go fast. Slightly narrower gravel-specific tires could be more efficient.
- Efficiency is Key: Speed isn’t just about grip; it’s about how much energy you lose to rolling resistance, aerodynamics, and vibration. Suspension helps manage vibration, opening up different tire possibilities.
This finding builds on the evolving understanding of gravel performance. While wider tires were a significant step forward from road setups, suspension appears to be the next frontier that shifts the optimization landscape. It reminds us that even in cycling, there’s always more to learn about what truly makes you fast and efficient on any given surface.
