HUNT 40 Limitless Gravel: Aero Aerodynamic Performance with Wider Tyres / Tires while Dropping 220 Grams

HUNT 40 Limitless Gravel review — HUNT 40 Limitless Gravel Wheels in Action

Front & rear specific rim profiles (36mm wide external front/35mm wide external rear), UD carbon spokes, CeramicSpeed Coated bearings and new H_Ratchet hub create an unmatched system weighing in at just 1328 grams per pair. – Hunt Bike Wheels

“Performance upgrade wheel company, HUNT, announced today the next evolution in the Limitless Width Aero Technology range: the new 40 Limitless Gravel Aero. HUNT’s in-house engineering team set out to create the absolute fastest mid-depth gravel race wheelset optimized for both 40mm and 45mm Schwalbe G-One tyres.”

“The engineering objective was to build on the class-leasing aerodynamic performance of the 42 Limitless Gravel Aero optimizing for wider racing tyres while significantly reducing system weight. The three-year development process yielded a wheel system with distinct front and rear specific hookless rim profiles, offering riders an unrivaled combination of four key metrics that directly improve performance: aerodynamic efficiency, aerodynamic stability, system weight, and tyre shape.”

Aerodynamic performance: Class-leading aerodynamic efficiency-to-weight and aerodynamic efficiency-to-depth performance:
- With a 45mm Schwalbe G-One AR tyre the 40 LGA UD produced the second lowest aerodynamic drag after the 3T discus 45/40 (0.34W difference). The 40 LGA UD produced lower drag than the Reserve 40/44, DT Swiss GRC 1400 SPLINE and the Zipp 303 Firecrest (0.5W, 1.04W and 1.95 respectively).
- With a 40mm Schwalbe G-One AR tyre the 40 LGA UD produced the second lowest aerodynamic drag after the 3T discus 45/40 (0.67W difference). The 40 LGA UD produced lower drag than the DT Swiss GRC 1400 SPLINE, Zipp 303 Fircrest and CADEX 35 AR (0.01W, 1.38W and 2.06 respectively).
- For an all-round gravel wheel, the 40 LGA UD offers the fastest overall package with both tyre sizes considered, but especially with the 45 mm tyre. The only wheel consistently faster than it, the 3T discus 45/40, achieves the aero efficiency with 320g in additional mass. The 40 LGA is faster than both the ENVE 3.4 and Reserve 40/44, whilst also being lighter.

Front & Rear-specific rim shapes to maximize aero efficiency while minimizing material mass:
- Front: 40mm Depth | 36mm External Rim Width | 27mm Internal Rim Width
- Rear: 41mm Depth | 35mm External Rim Width | 26mm Internal Rim Width
- Wider 4.5mm rim beads provide greater pinch flat protection than narrower traditional rim beads

System Weight: 1328g with UD Carbon Spokes, 1431g with triple butted aero wing steel spokes. 220 grams lighter than 42 Limitless Gravel Aero
Hubset: H_Ratchet 48T DBL – a new dual-sided ratchet system with 48-tooth drive delivers a fast 7.5 degrees of engagement. 6061 aluminum alloy hub shell with extra strong 7075-T6 alloy axle.
Bearing: HUNT have ve again partnered with industry leader, CeramicSpeed to spec CeramicSpeed Coated bearings on their UD Carbon Spoke variant of the 40 Limitless Gravel Aero wheelset.

“While weighing just 1328 grams with UD Carbon spoke technology, the new 40 Limitless Gravel Aero with a 45mm Schwalbe G-One AR tyre offers a 0.39-watt savings compared the preceding 42 Limitless with a 45mm tyre. Compared to relevant wheels in the mid-depth category, the 40 Limitless aerodynamically outperforms the relevant competitor wheels up to and including 45mm in depth, when mounted with modern 45mm gravel tyres. When aerodynamic drag-to-weight and aerodynamic drag-to-depth ratios are considered, the 40LGA significantly outperforms the competitive set. Full wind tunnel data can be found publicly in the research white paper.”

Project Background: Project Aims & Rider Needs

“The Limitless project began in 2017 and was first launched to riders in 2019 with the 48 Limitless Aero Disc which went on to win major races such as a stage at the Giro d’Italia. In 2021, HUNT developed the 42 Limitless Gravel Aero (42 LGA) wheelset aerodynamically developed for the world’s biggest one-day gravel races, such as Unbound. HUNT’s wind tunnel testing showed the 42 LGA to be faster aerodynamically than the wheels on offer at that time. The 42 LGA was used by HUNT sponsored athletes with success in many gravel races such as 5th at Unbound Gravel in 2023.”

“The aerodynamic performance was made possible by the extra wide external shape measuring 36mm at its widest point allowing airflow leaving the wider gravel tyres is better able to remain attached to the rim and thus reduce drag and improve handling. HUNT achieved this extra width while minimizing the rim mass with patented Limitless Width Aero Technology which utilizes a strip of low-density structural polymer inserted in a molded channel within the rim sidewall with carbon molded over it.”

“Through in-depth conversations with these riders, the feedback was consistent; the aero performance and stability of the 42 Limitless Gravel Aero was unmatched, but the riders wanted less weight to offset the weight penalty of running larger gravel race tyres. Over long gravel races such as Unbound or The Traka, riders find themselves accelerating hundreds of times: out of corners, closing gaps, and initiating a break, making low system weight and responsiveness critical to the overall performance of the wheel. With this input, HUNT engineering team set out to create a gravel race wheel system that maximized aerodynamic efficiency with 40-45mm tyres, while significantly reducing mass.”

Development Process: CFD, 3D Prototyping, Wind Tunnel Testing

“The engineering team at HUNT relied on three key technologies to develop, test, validate and re-test numerous rim profiles: CFD, 3D prototyping, and wind-tunnel testing. Over approximately 2500 hours of CFD (Computational Fluid Dynamics) analysis, the team evaluated 42 rim profiles to narrow down potential shapes. Once narrowed down to 3 front and 5 rear rim profiles, the team then 3D printed rims in sections, then assembled into fully built wheels to create representative prototypes for on-bike wind tunnel testing in a controlled and repeatable environment, representative of real-world wind conditions and yaw angles. Carbon fiber prototypes were then produced and re-tested in the wind tunnel against relevant competitors to validate the new designs and provide transparent data for riders to review and consider.”

“Throughout the 40 Limitless Gravel Aero Project, the HUNT engineers performed a combined total of 90 wind tunnel runs over two multi-day sessions to test, compare and validate the new profiles. The engineering team designed and tested the 40 Limitless Gravel Aero rim profiles around a 40mm and 45mm Schwalbe G-One AR and G-One RS tyre, both tyres chosen and raced by a majority of HUNT athletes.”

Aerodynamic Efficiency: Unique Front & Rear Hookless Profiles

“As learned in the SUB50 Limitless Speed Project, to maximize the aerodynamic efficiency of the wheelset as a system while reducing weight, the team chose to focus on creating the most efficient rim profile for managing clean airflow at the front of the bike. After evaluating initial profiles using CFD, then testing the most promising shapes in the wind tunnel, an engineered rim shape 40mm deep front paired with a 36mm external width provided the best overall performance across the full range of yaw angles with balanced weight to aero benefits.”

“The rear wheel encounters heavily disturbed airflow affected by the front of the bike and rider, changing how its profile contributes to the overall aero efficiency of the wheel and bike system. To minimize material in the rear wheel without negatively affecting system aerodynamics the team designed a slightly narrower, deeper and lighter rear rim profile with dimensions of 41mm deep and 35mm wide to handle the power transfer duties at the back of the bike.”

“HUNT patented Limitless Width Aero Technology offers ample stability and predictability, allowing our engineers to maximize aero benefits at the front of the bike by optimizing the shape and depth where has it the greatest impact on overall bike-and-rider system aerodynamics. The result, as evidenced by the wind tunnel data, is a faster and lighter wheel system that doesn’t compromise on handling characteristics.”

“The front and rear rim profiles of the 40 Limitless Gravel Aero feature hookless/TSS (Tubeless Straight Side) beads with an internal rim width of 27mm Front/26mm Rear, adhering to 2023 ERTRO standards, while being optimized for both 40 and 45mm tyres. Hookless rim technology allows HUNT to slightly reduce rim weight, improve manufacturing consistency, and improve aerodynamics at the tyre-to-rim interface by reducing the “lightbulb” effect that inwardly protruded hooks have on the tyre profile. A wider hookless bead profile also helps reduce the chance of pinch flats, due to the blunt, flattened profile.”

Low System Weight: A Sum of Components

“While designing a best-in-class set of hookless front and rear carbon rim profiles to maximize aerodynamic efficiency while reducing weight, the engineering and product development team was simultaneously seeking out other ways to reduce mass and increase performance across the wheel system.”

“For the first time, HUNT’s world tour-proven TaperLock UD carbon fiber spoke technology has been applied to a gravel race wheel after extensive testing of durability and ride characteristics. The UD carbon spokes offer 6% greater lateral responsiveness compared to steel spoke equivalents with significantly less weight (2.7g per spoke), allowing the design team to reduce the number of spokes used in the system. Unlike most carbon spoke options, the TaperLock system is fully true-able and adjustable. UD Carbon Spokes also offer high frequency vibration benefits, reducing rider fatigue over a long day of racing across rough roads.”

“To further reduce wheel system weight the HUNT engineering and development team worked with trusted industry-leading suppliers to develop and test a double ratchet hub system with a 48-tooth drive ring that uses less shell materials relative to pawl-based systems while increasing durability and protecting the hub internals from dust and external variables. With 48 contact points engaged simultaneously, the robust ratchet system is built to withstand the increased torque loads of wide range cassettes and single-chainring drivetrains. The HUNT H_Ratchet DBL hubset weighs just 314 grams per set for the carbon spoke version, while reliably offering a quick 7.5-degree engagement.”

Summary & Results: Real World Relevance & Unmatched Performance Metrics

“HUNT’s engineering team has spent two years developing a gravel race wheel system that offers improved aero efficiency over HUNT’s class-leading 42 Limitless with wider 45mm tyres, while significantly reducing system weight and maintaining the predictable and stable handling characteristics that differentiate Limitless projects from many other aero products.”

“The wind tunnel results as seen in the graphs depict the performance of HUNT 40 Limitless Gravel Aero wheels among a range of world class aero wheels commonly used in competitive gravel racing. The data shows owthat with both a Schwalbe 40mm and 45mm tyre, the HUNT 40 Limitless Gravel Aero has the second lowest aerodynamic drag while offering the fastest overall package when considering aerodynamic drag and system weight.”

“With the use of patented Limitless construction and UD Carbon Spokes, HUNT was able to design unique front and rear rim profiles that offers an extremely wide profile with a truncated edge (blunted spoke bed) to help airflow remain attached to the system, while providing weight saving of up to 220g compared to the 42 Limitless Gravel Aero. The design also offers enhanced traction, durability and pinch-flat protection for the harshest gravel terrain, with the wider internal rim width and thickened rim wall profiles to prevent pinch flats.”

Rider Benefits:

CeramicSpeed Coated available – The pro teams’ choice and the undisputed leader in low rolling resistance and high durability. One size does not fit all. These bearings are custom fitted for the HUNT H_Ratchet hubset at the CeramicSpeed factory, with extreme tolerances measured within a thousandth of a millimeter.
H_Care Lifetime Crash Replacement Included – We take care of your wheels, no matter what life throws at you. HUNT will repair or replace your damaged wheels free of charge under our H_Care policy.
Best-in-Class Rider Support – A team of riders in both the US and UK will support you before, during, and long after your purchase. Riders are investing in the HUNT product and service, neither of which will let them down.