AERO AT FULL VOLUME: THE ENGINEERING BEHIND 5AM GRAVEL LIMITLESS

Wider tyres and higher speeds means a new approach to gravel aerodynamics is needed.

Gravel racing is getting faster and with courses becoming more competitive, average speeds are increasing, and tyre widths once considered excessive are becoming the norm.

But wider tyres present a significant aerodynamic challenge. As tyre volume increases, managing airflow around the wheel becomes more complex. Traditional aero rim profiles, largely developed around narrower road tyres, aren't necessarily optimised for the demands of current gravel racing.

For our engineering team, the challenge was to create a wheel system that could deliver measurable aerodynamic performance with 45–50mm gravel tyres, without compromising weight or handling.

The result is the 5AM Gravel, which is part of our Limitless range, informed through our 5-Stage Aero Development process and built around a new Aero Maximised rim architecture, specific to our Limitelss wheels.

Aero Maximised: Two Profiles, One System

The front and rear wheels experience very different aerodynamic conditions. The front wheel meets relatively clean airflow, while the rear operates in the turbulent wake created by the front wheel, frame and rider.Rather than applying the same rim profile to both wheels, we engineered each independently to maximise the performance of the complete system.At the front, a 54mm deep, 45mm wide rim provides the profile required to manage airflow around high-volume gravel tyres. Its greater width helps create a more effective transition between tyre and rim, reducing aerodynamic drag.At the rear, a 49mm deep, 38mm wide profile balances aerodynamic performance with reduced material and weight, recognising the different airflow conditions it operates within.We call this approach Aero Maximised, or the Aero Mullet, our AM range.The principle is straightforward: put the aerodynamic performance where it matters most, without adding unnecessary weight where the gains are smaller.

Limitless Width Aero Technology: Breaking the Weight Penalty

Wider rim profiles can improve aerodynamic performance with wider tyres, but traditionally they come with a penalty: additional carbon, additional weight.

Our patented Limitless Width Aero Technology was developed to overcome this challenge. By incorporating a low-density structural material into the rim construction, we can achieve the wide external profiles needed for aerodynamic performance without relying entirely on additional carbon fibre.

This allows us to engineer a wide, aerodynamically optimised rim while maintaining a competitive system weight. For the 5AM Gravel Limitless Ti_UD Carbon Spoke wheelset, that means a claimed weight of just 1,317g. It's a crucial part of the engineering equation. Aerodynamic efficiency is valuable on fast, open gravel sections, but the wheel still needs to respond when accelerating out of corners, climbing steep gradients or navigating changing terrain.

Designed Around the Tyre, Not just the Rim

A wheel does not operate in isolation. Once a tyre is fitted, the aerodynamic properties of the complete system change. That's why the 5AM Gravel Limitless was developed specifically around modern gravel tyre widths, rather than adapting a road rim profile to a wider application. Our engineering team focused on 45–50mm tyres, studying how tyre shape, rim width and rim depth interact across different wind angles. The 27mm internal rim width supports the high-volume tyres increasingly used in gravel racing, while the external rim geometry is designed to manage airflow around the tyre and into the rim profile.

The aim for us wasn't simply to create the most aerodynamic rim on paper. It was to deliver aerodynamic efficiency in the configuration riders actually race. This is why we have worked with our athletes across races to test and design the 5AMG. Because when you're running a 50mm gravel tyre, the complete tyre-and-wheel system is what matters.

Tested Against the Competition

The final validation took place at the Silverstone wind tunnel, where the 5AM Gravel Limitless was tested against 11 competing wheelsets. With 50mm Vittoria Terreno T30 tyres, the 5AM Gravel Limitless Ti_UD Carbon Spoke recorded the lowest aerodynamic drag of all 12 wheelsets tested. It was also the lightest wheelset in the test. With 45mm Vittoria Terreno T30 tyres, the Steel Spoke version achieved the lowest aerodynamic drag in the field. These results demonstrate the thinking behind the entire development programme: aerodynamic performance needs to be assessed with the tyres gravel racers actually use, not just under idealised conditions. The findings also reinforce the benefits of our Aero Maximized architecture, with a wider, deeper front profile working alongside a lighter, narrower rear.

Aero at Full Volume

Gravel racing no longer demands a choice between wide tyres and aerodynamic performance. The 5AM Gravel Limitless brings together the tyre volume required for modern gravel racing and the aerodynamic engineering developed through generations of our Limitless road wheels. From the independent front and rear profiles to our patented Limitless Width Aero Technology, every decision serves the same objective: reduce drag, minimise unnecessary weight and maximise performance at race speed.

The HUNT 5AM Gravel Limitless uses an Aero Mullet design with a 54mm deep, 45mm wide front rim and a 49mm deep, 38mm wide rear rim, optimised for 45–50mm gravel tyres. Developed through HUNT's 5-Stage Aero Development process, the wheelset uses patented Limitless Width Aero Technology to reduce the weight penalty of wider rims. At Silverstone wind tunnel, the Ti_UD Carbon Spoke version recorded the lowest drag among 12 wheelsets tested with 50mm Vittoria Terreno T30 tyres.

5AM Gravel Limitless. Aero at Full Volume.