HUNT present the 42 LIMITLESS Gravel Disc, a new wheelset for your Gravel-Bike, which is designed to let you fly faster over gravel tracks by aerodynamic optimisations – and this with up to 700 x 54C wide tyres. All information and details about the new wheels can be found here in the official press release.
With the 42 LIMITLESS Gravel Disc, HUNT set out to develop the premier performance gravel wheelset, optimising gravel-specific aerodynamics through patented LIMITLESS Width Technology, and balancing those aerodynamic gains with another critically important attribute for riders moving fast over inconsistent surfaces: crosswind stability (steering moment). The need was driven by the increased level of gravel riding and racing, with top-tier events all over the world gaining the attention and participation of some of the most talented cyclists on the planet. Gravel riding began as a means to escape vehicle traffic and pavement, unlock new routes and destinations, and add new adventure into our riding experiences. While all of that still rings true in 2020, more riders are heading off-road and looking to maximise their performance. What began on adapted road or cyclocross bikes, now has its own rapidly growing category of bikes and equipment optimised for speed and efficiency across rugged terrain. As with road racing technology several years ago, the fastest gravel riders are now rethinking their equipment selections and employing aerodynamically designed skinsuits, helmets, frames, and wheels. With industry-leading engineering and design talent in-house, HUNT endeavored to set a new standard for gravel-specific wheel performance.
Introduction and Process
The all-new HUNT 42 LIMITLESS Gravel Disc wheelset was designed for riders seeking maximum aerodynamic benefit, category-leading steering moment (crosswind stability), and low weight relative to depth. The task of developing an aero-optimised gravel wheelset presents unique challenges. From an aerodynamics perspective, the tyre is the first object affected by wind. Aggressively treaded tyres almost immediately turn the wind into “dirty air,” making aerodynamic optimisation much harder to achieve, particularly given the vast differences from one tyre to another.
To begin the process of improving on wheel aerodynamics in gravel racing, HUNT engineers went to the wind tunnel with several leading gravel tyres and top wheelsets (including the HUNT 48 LIMITLESS Aero Disc), to better understand how aero wheels compare to alloy gravel wheels designed with no focus on cutting through the air. Once the team extrapolated the power data yielded from this, we were able to determine that when considering the speed, power, and distance of a rider at the sharp end of a top-tier race, the use of an aerodynamically optimised wheelset could save seven to nine minutes across the course of a 200-mile race.
Luisa Grappone and HUNT development engineer Chris Colenso designed a completely new rim profile with an effective aerofoil shape optimised for a wider tyre. With consideration for the differences in widths and tread patterns of different tyres, the 42 LIMITLESS Gravel Disc is optimised to provide world-leading aerodynamics with most 38-42c tyres.
While designing 3D CAD models and new rim shapes for rapid prototyping and CFD analysis, HUNT gathered tyre preference data from a myriad of gravel races in the US such as SBT GRVL, Mid South, and Rebecca’s Private Idaho. It was determined that 38mm tyres were by far the most common among professionals and those participating in the most competitive endurance events. From there, Luisa and Chris began to develop models and 3D-printed samples for initial wind tunnel sessions.
Looking Beyond Drag
As a general rule, when comparing two aerodynamically profiled rims, deeper shapes will provide greater aerodynamic benefits. When studying equipment choices at premier gravel events, it was apparent that riders generally favored shallower rims, presumably to achieve light weight, compliant ride characteristics, and crosswind stability; all at the expense of substantive aerodynamic gains. The vibrational losses associated with deep rim profiles, along with the energy lost fighting hours of crosswinds, can cause fatigue over long racing distances. After testing a number of shapes and depths, HUNT identified the opportunity to develop the ideal solution: an extra-wide, aerodynamically optimised 42mm profile with outstanding crosswind performance and low relative weight.
Understanding Crosswind Stability
During testing, we monitor various elements of aerodynamic performance, including side forces that act on the rims, and the effect those forces have on the steering moment (a tool for measuring crosswind stability). As with our previous projects, our wheels are tested through a range of effective yaw angles between negative 20 degrees and positive 20 degrees.
In real-world riding conditions, wind does not distribute forces evenly. The frequency of effective yaw angles experienced by a rider follows Gaussian distribution (bell curve), based on the variables of wind direction and speed, as well as rider direction and speed. Simply stated, low yaw angles have a greater probability of occurring in real-world riding conditions than high yaw angles. According to well-referenced data from scientific and industry sources, “a vehicle will spend at least 70% of the time at yaw angles below 10 degrees.” (Cooper, 2003). In the context of riding, the rider will spend approximately 42 minutes experiencing yaw angles between negative and positive 10 degrees over the course of an average one-hour ride.
Wind Tunnel Data
The wind tunnel results below depict the performance of HUNT 42 LIMITLESS Gravel Disc wheels among a range of world-class aero wheels commonly used in competitive gravel racing. The data suggests that the HUNT 42 LIMITLESS Gravel Disc is the most aerodynamic gravel wheelset, offering the rider a small power gain of 0.05W, or 6 seconds of advantage when compared to the next best-ranked offering over the course of a 200-mile race averaging a speed of 32 km/h and power output of 317W (Note: the 3T Discus 45|40 was not available to test, as it was not released to the public when testing occurred).
With the use of patented LIMITLESS construction, HUNT was able to create a wheelset that offers an extremely wide rim profile with a truncated edge (blunted spoke bed) to help airflow remain attached to the system, while maintaining low overall weight and providing day-in and day-out performance and durability on the harshest gravel roads.
CeramicSpeed: The Coated Advantage
Whilst the demands of modern performance riding share many similarities across multiple disciplines, the increasing diversity of competitive riding and racing requires highly specialised engineering solutions that often go unseen. This is where our partnership with CeramicSpeed takes center stage.
CeramicSpeed’s new coated bearings are 75% tougher than their standard hardened steel races, boasting an average lifetime seven and a half times longer than other non-coated solutions. While longevity is of paramount importance off-road, so too is resistance to corrosion. Off-road conditions involve increased presence of contaminants like moisture, dust, and mud. CeramicSpeed’s coated bearing solutions are designed and tested extensively to ensure that failure due to corrosion and contamination is negligible.
In addition to increased longevity, the even and smooth surface of CeramicSpeed coated bearings dramatically reduces friction, contributing to a faster overall system.
Thanks to a comprehensive R&D program, CeramicSpeed’s resilient solutions are backed by a 6-year warranty. This offers riders the freedom to put the 42 LIMITLESS Gravel Disc wheelset through its paces in the most challenging training and racing conditions without fear of failure.
Overview of all facts about HUNT 42 LIMITLESS Gravel Disc wheels
- Profile U-shaped aero profile
- Rim depth 42 mm
- Rim width (external) 36 mm
- Rim width (internal) 25 mm
- Weight 1.548 g
- Hubs FastEngage 7.5 hubs with Centerlock mount and 48 ratches, Engagement angle is 7.5°
- Price € 1,489
- Availability pre-order now, delivery from February 2021
Our opinion about the HUNT 42 LIMITLESS Gravel Disc wheels
The idea of speed and racing is becoming more and more an important topic in the gravel sector, and manufacturers of gravel bikes and components should not turn a blind eye to this. The new aerodynamically optimised HUNT wheels look interesting at first glance – if crosswind susceptibility stays within reason and comfort is not completely lost. We are looking forward to a first test!
For more information about the HUNT 42 LIMITLESS Gravel Disc wheels, visit huntbikewheels.com
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Words: Photos: HUNT