Thanks to extensive wind-tunnel testing and Vuonoa Ti_UD carbon spokes, Hunt is saying its new 5AM Limitless Ti_UD Carbon Spoke Wheelset is its “fastest all-round road racing wheel system to date” when mated with a 30mm tire fitted.
“This is the third-generation Limitless wheel and we are confident that with a 30mm tyre fitted this is the fastest thing you can buy, and that’s a really cool place to be,” says Hunt’s senior development engineer Paddy Brown.
At the center of the 5AM Limitless Ti_UD Carbon Spoke Wheelset is a 58mm rim up front, and 55mm at the rear, taking the approach that more material at the leading edge, creates a better aerodynamic signature, while relying on a blend of T700, T800 and T1000 carbon fibers, combined with high-modulus Mitsubishi Pyrofil HR4012M.
“Now we’ve taken that a step further and gone to a slightly shallower and narrower rim on the rear. We’re looking at about a 50g lighter rim at the rear than on the front. When you’re talking about a 1,212g pair of nearly-60mm deep wheels with exceptional aero performance and really lightweight, it’s significant. It’s the ideal wheel for something like Milan-San Remo, where you want peak climbing performance and then aero gains that’ll be extremely important in a sprint finish. You can’t have a weak spot.”
“The front wheel encounters clean air, presenting the greatest opportunity to reduce drag,” says Hunt. “By increasing rim depth and width while minimizing hub and spoke drag with a reduced spoke count and hidden spoke nipples, the 5AM system maximizes aerodynamic efficiency where it matters most. Patented Limitless Technology in the front wheel enables a wider aerodynamic shape without the weight penalty, by utilizing low-density structural polymer (0.7g/cm3) moulded into the rim sidewall between carbon layers (1.6g/cm3). The wider, blunt rim shape maintains laminar airflow (attachment) through higher wind angles, resulting in more stable handling characteristics, as well as preparing the airflow for the wider-than-tires frame down tube. The rear wheel operates in turbulent airflow, downstream of the front wheel, frame and rider movement. In this position, minimizing weight and maximizing power transfer become more important than absolute aerodynamic drag reduction. The rear wheel, therefore, leverages a shallower, narrower rim paired with additional spokes to deliver responsiveness and efficient transmission of every watt to the road,” adds the British brand.
All things considered, Hunt boasts that the 5AM Limitless Ti_UD is 4.35 watts faster than ENVE 4.5 Pro in the wind tunnel at 45km/h (28mph) – yaw angles from 20° to -20° – 1.74 watts faster than Roval Rapide Sprint with 30mm tires, and 1.99 watts faster than Scope Artech 6 – again fitted with 30mm tires.
Additionally, Hunt did some outdoor testing with Dr Barnaby Garrood at Aerosensor at a target speed of 41km/h (25.5mph), concluding that the 5AM Limitless Ti_UD is 5.9 watts faster than Scope Artech 6 and 8.5 watts faster than the Zipp 404 Firecrest, again when fitted with 30mm tires.
“This final stage of validation has allowed us to accurately measure the impact of rotational drag for the first time, showing the impressive reduction we have managed to achieve through reduced front wheel spoke count and hidden spoke nipples,” says Hunt.
Rob Fields, Hunt’s head of engineering, says, “We see a lot of our competition only doing stages one and two. Some do three. I haven’t seen many wheel manufacturers do rider-on testing. Bike manufacturers tend to. They tend to use mannequins, and not many of them are doing outside aero testing. The Tour teams are doing some of that aero testing because we know that Aerosensor has worked with some. We are going to that level because we believe you have to understand all those different things to make people in the real world faster.
“We’ve spent serious time and money learning and experimenting to make sure that what we’re doing is right and relevant and to guide the decisions we make. This is us committing resources, energy and money to producing the best product. Wind tunnels are a great tool because they’re repeatable, but they are just a tool that doesn’t show you the entire story. In a wind tunnel, you are not capturing all of the force and energy that goes into riding a bike in the real world. In the wind tunnel, you drive the wheels from motors underneath. Now, some of that drag is captured in the balance, but some of it is not. You’re expending energy rotating those spokes through the air, and not all of that is captured in the wind tunnel, but it is captured outside. This is why the outside aero testing is so important to us. The only way to measure how a real human is riding a bike outside is to do it. We’ve invested in the equipment and, more importantly, the time needed to get repeatable figures. This fifth stage of our aero testing, the validation: I haven’t seen anyone else doing it, and it feels like the only way to get representative real-world data, with the caveats that it is a bit messier and it is harder to do. We’ve built up the capability because we think it’s really important.”
Needless to say, Vuonoa’s Ti_UD carbon spokes play a critical role in reducing both weight and rotational drag, while also bolstering tensile strength to over 400kgf per spoke, requiring a lacing pattern of only 15 at the front, 18 at the rear, in a 2:1 pattern, weighing in at just 1.7 grams each.
Rob Fields says, “As far as I can tell, we’re the only people playing a game where we want to lower spoke count, because we’ve seen a big aero improvement, particularly on the front wheel, hence we’ve gone to 15 spokes on the front
“The two-to-one lacing pattern and the radial [lacing] on one side of the front effectively hides as many spokes as close as you possibly can to the centre line of the wheel. You get more spokes out of the air at low yaw angles. We’ve also played with different spokes. Where you’ve got two-to-one lacing, we use thicker spokes on the side with fewer of them. A thicker spoke with more carbon balances out two thinner, smaller, lighter and more aerodynamic spokes, so it really is all about system optimisation. We’ve not just thrown all the same spokes at it; we’ve made conscious decisions to try and find all those little gains to make them as aero-efficient as possible. As far as I’m aware, no one is quite playing this level of optimisation.”
Elsewhere, the new wheels feature a hooked rim with a 23mm internal width, along with 34.5mm external width up front and 30mm at the rear, while things spin on Hunt’s own Chase SLC, CNC-machined 7075-T6 aluminium with a H_Ratchet DBL 48T drive system that provides 7.5° of engagement.
The Hunt 5AM Limitless Ti_UD Carbon Spoke wheelset with stainless steel bearings sells for £1,999, while the CeramicSpeed version fetches £2,489.
Hunt
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