New Hunt SUB50 Limitless wheelset outperforms competition according to white paper

All-round race wheels weigh 1,383g and use asymmetric rims to cut through the air

By Simon von Bromley

Published: Thursday, 01 February 2024 at 15:00 PM

Hunt has unveiled the SUB50 Limitless Aero Disc wheelset, its new flagship carbon wheelset for road bikes.

Building upon its previous-generation Limitless wheelsets, the Hunt SUB50 Limitless Aero Disc wheels pair a radically wide, 34.2mm front rim with a narrower 30mm-wide rear rim.

Both rims are 49.5mm deep and feature 23mm internal widths. The rims also use a hookless design, which Hunt claims offers both aerodynamic and weight benefits.

Hunt says data captured at the GST wind tunnel in Germany shows the SUB50 Limitless Aero Disc wheels offer “class-leading aerodynamic efficiency-to-weight” with both 28 and 30mm-wide tyres.

The new SUB50 Limitless rims are also paired with Hunt’s new H_Ratchet DBL hubs, which weigh a claimed 332g per set and feature a 40-tooth double-ratchet freehub engagement system similar to that found in DT Swiss 350 hubs.

There are three models in the SUB50 Limitless Aero Disc range. Prices start from £1,479 / $1,799 / €1,849, for a wheelset built with steel spokes and bearings, and rise to £2,289 / $2,789 / €2,749 with ceramic bearings and carbon spokes.

With ceramic bearings and Hunt’s UD carbon spokes, claimed weights start from 1,380g for complete wheelsets. A set Hunt showed us at BikeRadar’s Bristol HQ prior to the launch weighed only 3g more.

The fastest all-round road race wheelset?

Hunt has moved to using a wider front rim paired with a narrower rear for its SUB50 Limitless Aero Disc wheelset. – Hunt

Hunt says the design goal for its new-generation Limitless wheelset was to create the “fastest all-around road race wheelset up to and including 50mm in depth for both 30mm and 28mm tyres”.

With other brands, such as Roval and ENVE, now using different rim profiles front and rear to maximise the aerodynamic performance and weight of their wheelsets, Hunt opted to do something similar.

Over “approximately 2,500 hours of CFD (Computational Fluid Dynamics) analysis”, Hunt’s team modelled and evaluated 38 profiles for the front rim and 18 for the rear.

Of these, three front and four rear rim profiles were then 3D-printed and built up to create representative prototype wheelsets for wind tunnel testing.

Hunt SUB50 Limitless Aero Disc prototype in the GST wind tunnel
CFD-developed rim prototypes were 3D-printed, built into complete wheels and validated in the GST wind tunnel. – Hunt

After the performance of these initial prototypes was validated, Hunt says it then produced carbon fibre prototypes, which were re-tested in the wind tunnel against a long list of popular competitor wheelsets.

These wheelsets included Roval’s Rapide CLX II, ENVE’s SES 4.5, Zipp’s 454 NSW and 303 S, Princeton’s Peak 4550, Shimano’s Dura-Ace C50, DT Swiss’s ARC 1400 DICUT 50 DB and more.

In total, Hunt says it performed 90 wind-tunnel runs over two days at the GST wind tunnel in Germany. All wheelsets were mounted to a Cannondale SystemSix and were tested with both 28 and 30c Schwalbe Pro One TLE tyres.

Hunt SUB50 Limitless Aero Disc in the GST wind tunnel
Carbon fibre prototypes were pitted against popular competitor wheelsets in the GST wind tunnel. – Hunt

Measurements were taken from -20 to 20 degrees of YAW and the results analysed using Mavic’s Wind Averaged Drag (WAD) weighting.

This uses yaw measurements taken from real-world riding to give importance ratings to data, enabling results to be combined into a single averaged WAD value for each wheelset.

A rider or mannequin legs were not used in order to improve the resolution of the data and enable the small differences between each wheelset to be more easily perceived.

Hunt SUB50 Limitless WAD results table
Hunt’s white paper includes wind-averaged drag data from the GST wind tunnel, alongside tyre width and wheelset weight data from competitor models. – Hunt

According to Hunt, the results – which have been published in a detailed white paper – show the new SUB50 Limitless Aero Disc wheelset outperforms all the wheelsets, in terms of what it refers to as “aerodynamic efficiency-to-weight” (which looks at aerodynamic performance in the context of a wheelset’s weight).

The only exception was the DT Swiss ARC 1400 DICUT 50 DB wheelset, with a 28c tyre. According to Hunt, the DT Swiss wheelset’s narrower, 20mm internal rim width offers a narrower tyre profile, improving its aerodynamic efficiency.

In Hunt’s opinion, though, there’s a potential real-world trade-off for this in terms of higher rolling resistance and reduced comfort and grip.

Hunt also says the new SUB50 Limitless Aero Disc paired with a 30c tyre offers a 1.4-watt improvement over the outgoing 48 Limitless wheelset with a 28c tyre.

Hunt SUB50 Limitless Aero Disc wheelset efficiency-to-weight comparison (28mm tyre)
According to Hunt, the SUB50 Limitless Aero Disc wheelset offers better aerodynamic efficiency for its weight, rim depth and rim width than any of its key competitors. – Hunt

Don’t forget about weight

At the same time, Hunt notes that feedback from sponsored professional riders consistently requested the same aerodynamic performance at a lower overall weight.

For context, Hunt’s original 48 Limitless wheelset has a claimed weight of 1,618g with steel spokes or 1,511g with carbon spokes (the 48 Limitless UD Carbon Spoke Disc wheelset we tested weighed 1,558g with tubeless tape and valves).

The lowest claimed weight of 1,380g, then, represents a minimum potential saving of 131g versus Hunt’s lightest Limitless configuration previously available.

Hunt SUB50 Limitless Aero Disc wheelset
Alongside looking to improve on aero performance, Hunt also sought to cut significant weight from its flagship road racing wheelset. – Simon von Bromley / Our Media

According to Hunt, this was achieved by narrowing the rear rim, moving to a hookless design and the use of its new (and lighter) H_Ratchet DBL hubs.

A SUB50 Limitless Aero Disc wheelset seen by us prior to the launch weighed 1,383g with tubeless rim tape installed, only 3g more than the claimed weight.

Hunt SUB50 Limitless Aero Disc wheelset on scales
A Hunt SUB50 Limitless Aero Disc wheelset (with carbon spokes) shown to us prior to the launch weighed 1,383g. – Simon von Bromley / Our Media

As on previous-generation Limitless wheelsets, the radically wide rims continue to utilise Hunt’s patented Limitless Width Aero Technology.

This sees strips of ‘low-density structural polymer’ inserted into a moulded channel in the rim sidewall, with additional carbon fibre layered over it.

This, Hunt says, allows for an extra-wide external rim without adding excessive weight or necessitating the use of a similarly wide internal rim (which would compromise compatibility with narrower road bike tyres).

Hunt SUB50 Limitless Aero Disc rim
Hunt continues to make use of its patented Limitless Width Aero Technology. – Hunt

H_Ratchet DBL hubs

Hunt’s latest high-end road hubs feature a shell constructed from 6066 aluminium alloy and a 7075-T6 alloy axle.

Weighing a claimed 332g per set, Hunt says a new 40-tooth double-ratchet system offers 9-degree freehub engagement and is designed to withstand high torque loads.

Hunt H_Ratchet DBL hubs
Hunt’s new H_Ratchet DBL hubs are said to be lighter and offer improved freehub engagement. – Hunt

According to Hunt, this offers increased engagement surface area at a lower weight than its previous, pawl-based hub systems. 

The hubs are completed with double-sealed bearings, with steel bearings as standard or with CeramicSpeed ceramic bearings as an optional upgrade.

Hunt SUB50 Limitless Aero Disc expanded rear hub
The H_Ratchet DBL hubs feature a 40t double-ratchet system, double-sealed bearings and a ceramic-coated freehub.

An updated Shimano Hyperglide freehub also features a H_Ceramik reinforced ceramic coating, which is claimed to protect the freehub from cassette gouging and negates the need for a steel anti-bite strip.

Hunt says one of its sponsored athletes, Boru McCullagh, has been testing the new hubs (built into its 48 Limitless Gravel Adventure wheelset) on “a fully-loaded, around-the-world journey”, and has so far ridden more than 25,000km on a single set.

Hunt SUB50 Limitless Aero Disc wheelset specifications and availability

The SUB50 Limitless Aero Disc wheelsets are available to pre-order now, with wheelsets shipping in late February 2024 for options with steel bearings, or April 2024 for configurations with CeramicSpeed bearings.

Hunt SUB50 Limitless Aero Disc UD Carbon Spoke, CeramicSpeed bearings

Hunt SUB50 Limitless Aero Disc UD Carbon Spoke, stainless steel bearings

Hunt SUB50 Limitless Aero Disc Steel Spoke, stainless steel bearings