The Weight Myth: When Does Aero Beat Weight on a Climb?

Lighter has always been considered faster uphill. But what happens when the climb gets faster, the gradients get shallower, and aerodynamics start to play a bigger role?

For multiple National Hill Climb Champion Andrew Feather, every gram matters. His bike, training and equipment have all been optimised for one thing: getting uphill as quickly as possible.

But the 2026 National Hill Climb Championships present a different challenge.

Taking place on Porlock Toll Road, the 6.7km course averages just 5.5%, making it significantly faster than a typical UK hill climb. With higher speeds comes greater aerodynamic resistance, raising an interesting question: could a deeper, more aerodynamic wheel actually be faster uphill than a lighter alternative?

To find out, we headed to Porlock with Andrew and our engineering team to put three very different wheel depths to the test.

A Different Approach to Climbing

Andrew has built his reputation on producing huge power on steep gradients, often riding out of the saddle. But on a faster course like Porlock, raw power alone won't be enough.

He's been working on a more aerodynamic riding position, allowing him to maintain his preferred out-of-saddle technique while reducing frontal area.

With a lower front end, narrower handlebars and a more forward weight distribution, his setup looks very different from a traditional hill climb bike.

And with his position already optimised, the next opportunity was wheel choice.

Three Wheel Depths.

For this test, we compared three front wheels:

• 4AM Limitless: 49.5mm deep

• 5AM Limitless: 58mm deep

• Prototype: 100mm deep

Rather than simply comparing wheel weights or relying on theoretical aerodynamic data, we wanted to understand how these differences translate into actual climbing performance.

We focused on the front wheel, which our previous testing has shown to have the greatest aerodynamic influence, while keeping the rest of the setup consistent.

The testing took place on a 600m section near the top of Porlock Toll Road, with repeated efforts in both directions.

Andrew completed approximately 30 runs, targeting around 440W per effort.

To ensure the results were as accurate as possible, we used our Aerosensor system to measure changes in wind conditions and aerodynamic drag, alongside an AeroBody laser position sensor to monitor Andrew's riding position.

His power meter was calibrated before every run, while his weight was monitored throughout the day to account for changes caused by sweat loss.

The 4AM was also tested repeatedly as a baseline, helping us account for changing environmental conditions.

It was a demanding day of testing, particularly in the middle of a UK heatwave, but controlling these variables was essential to identifying the relatively small differences between the wheelsets.

The Results: Aero Isn't Always Faster

The aerodynamic results were clear. The deeper wheels delivered the lowest drag, with the 100mm prototype offering anaerodynamic saving of approximately 5 watts.

But aerodynamic efficiency is only part of the equation.

When we extrapolated the results across the full Porlock climb, accounting for both wheel weight and aerodynamic drag, the picture became much more interesting.

At 400W, the shallowest 4AM setup was marginally faster, despite its aerodynamic disadvantage.

However, at 450W, the deeper wheels began closing that gap.

At higher speeds, aerodynamic drag becomes increasingly important. And with an athlete capable of sustaining Andrew's power output, the benefit of a deeper rim can almost entirely offset the additional weight.

For Andrew, Porlock sits right on the tipping point between aerodynamic efficiency and weight savings.

It's a reminder that the fastest wheel isn't necessarily the lightest or the deepest. It's the one that delivers the best overall performance for the rider, terrain and conditions.

What Does This Mean for Your Wheel Choice?

While Andrew's ability to sustain around 450W puts him firmly in a different category from most riders, the findings offer some useful insight into wheel selection.

On steep climbs at lower speeds, weight remains a significant factor. As gradients decrease and speeds increase, the aerodynamic advantage of deeper wheels becomes more relevant.

But even on a relatively shallow climb like Porlock, our testing showed that a lighter setup can still come out ahead.

For most riders, the balance of low weight and aerodynamic efficiency offered by the 4AM and 5AM Limitless wheelsets remains a compelling choice.

It's not simply about chasing the lowest weight or the deepest rim. It's about understanding how those characteristics work together in real riding conditions.

Engineered for Real-World Performance

The results also highlight why real-world validation is such an important part of our development process.

Wind tunnel testing and CFD simulations allow us to understand aerodynamic performance in controlled environments, but taking our wheels onto the road with athletes like Andrew helps us understand how those gains translate into actual riding.

From changes in wind direction to riding position and power output, the real world introduces variables that can't be ignored.

And sometimes the most valuable result isn't a clear winner, but a better understanding of where the performance advantages lie.

For Andrew, the final decision may come down to the conditions on race day. For us, it's another opportunity to turn real-world data into better-performing wheels.

Watch the full film below to see Andrew and the HUNT engineering team put the weight-versus-aero debate to the test.

Watch The Weight Myth on YouTube