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HUNT SUB50 Limitless Aero Disc: Less drag, less weight

HUNT has quickly gone from being the hunter to the hunted, and their constant improvement, together with probably the best price-quality ratio in the market, put them at the top of the wheel manufacturing industry.

This time, the British brand is presenting a wheelset with different rim profiles for front and rear, looking for the best performance-to-weight ratio. The HUNT SUB50 Limitless Aero Disc, with a weight of 1.380g per pair, are an upgrade of the 48mm Limitless model, which became the first road wheels to feature an external rim width over 30mm.

Ahead of the curve

HUNT was forward-looking in 2018 when optimizing around 28mm tires for the 48 Limitless project. In 2024, based on emerging trends, they considered that the next generation of wheels had to be optimised for tires ranging from 28mm to 30mm. Apparently, a growing number of professional riders have already adopted 30mm tires, and wider, in search of incremental gains in aero efficiency, vibration reduction, cornering traction, and lower rolling resistance.

Even if the people at HUNT are intrinsically motivated to innovate, the pressure of their competitors was another important factor in speeding up the production process of the HUNT SUB50. Since the launch of their previous road model, other wheel manufacturers used similar design concepts, and some new wheelsets came onto the market offering impressive aero-to-weight advantages for riders.

Across the industry, there has also been a move to the use of hookless rim profiles with some potential aerodynamic and weight reduction benefits. All in all, these innovations from some of their competitors triggered the start of the SUB50 Limitless Speed Project.

An exhaustive production process

The engineering team at HUNT relied on three key technologies during the production process: an initial exploration of potential rim profiles through CFD (Computational Fluid Dynamics), 3D prototyping of the shortlisted ones, and wind-tunnel testing of the carbon fiber prototypes against relevant competitors.

HUNT broadly defines CFD as “the use of a computer model to calculate the drag over an object in particular wind conditions”. This is achieved by creating a network of small cells that fill the space to be modeled, and generally become smaller closer to the surface of the model and in areas where the model’s geometry is more complex.

This CFD model and the resulting design proposals would later be validated with wind tunnel testing. This wind tunnel testing includes 3D-printed wheel models tested against major competitors. A final wind tunnel test with production samples versus the full competitor set is then used to validate the performance of the production wheels.

As a result of all this process, HUNT came up with a front rim that is 49,5mm deep, and 34mm at its widest point. The rear rim is not as wide (30mm), and this is because the HUNT engineers defend that the heavily disturbed airflow influenced by the front of the bike and the rider make that the rear wheel is not as sensitive to aerodynamics so that they can focus more on reducing weight than optimising aerodynamics. It contradicts what we have seen in the past, with some competitors pairing a shallower front rim with a deeper rear rim driven by concerns over the handling of deeper section front wheels. 

Pro rider feedback

The pro riders who have tested this wheelset highlight the stability and predictability in changing wind conditions, chaotic feed zones, and dynamic sprint situations like a much shallower wheel. This stability is attributed to the wide radius at the rims’ spoke bed, which achieves more consistent and controlled stall conditions.

Even if we mentioned pro riders, the benefits of the SUB50 Limitless Aero Disc can have an even bigger impact on those who usually ride at lower average speeds. At high speeds, the rider experiences more ‘head on’ wind yaw angles, whereas lower average speeds generate wider average wind yaw angles.

In addition to the rim, all the components of the wheelset had to be optimised in order to meet the weight demands of the pro peloton. In previous launches, we already wrote about their TaperLock UD carbon fiber spoke technology and how they are fundamental to reducing the overall weight.

Furthermore, the HUNT engineering team worked with the suppliers of the brand to develop a double ratchet hub system with a 40-tooth drive ring that achieves the same level of reliability for which HUNT hubs are known, offering increased engagement surface area while using less shell materials relative to the pawl-based systems.

Internal and external comparisons

One of the things we really appreciate about Hunt Bike Wheels is their transparency. All their launches are complemented by a white paper explaining the development process and all the tests carried out before placing the product on the market.

In this case, 56 rim profiles were analysed and 10 competitor wheelsets were tested and compared. In total the team at HUNT carried 90 wind tunnel test runs and 2.500 hours of Computation Fluid Dynamics Analysis.

From the document, we can extract that, compared to the 48 Limitless Aero Disc, the SUB50 reduced drag by 1,4 watts with a 28mm tire, and reduced overall wheelset mass by over 130 grams, resulting in 1.378g per pair for the carbon spoke version. It means that the HUNT engineering team has reduced overall aero drag and weight while increasing tire width by a full size.

Some of the wheels from leading competitors that are comparable when it comes to rim depth and internal width tested aerodynamically faster than the HUNT’s model with a 28mm tire, predominantly due to the competitor’s narrower profile. However, the HUNT SUB50 excelled in the tests carried out with a 30mm tire, not only when it comes to aerodynamics but rolling resistance, grip, and comfort too. So when aerodynamic drag-to-weight and aerodynamic drag-to-depth ratios are considered, the SUB50 significantly outperforms the competitive set. These wheels also perform similarly to much deeper wheels.

Compliance and availability

Both front and rear rim profiles feature hookless/TSS (Tubeless Straight Side) beads with an internal rim width of 23mm, adhering to 2023 ETRTO standards for use with 28mm and wider tires. Also related to safety, the hookless rim technology helps reduce the chance of pinch flats, due to the blunt, flattened profile.

Less drag, less weight, and wider tires. The first delivery of the mid-depth HUNT SUB50 Limitless Aero Disc wheelsets are already available for pre-order, with most stock arriving to riders in late February 2024 and CeramicSpeed wheelsets arriving in late April 2024.