A slanted vehicle, equipped with various sensors, rolling thousands of kilometres through the USA: it’s with this modified scooter that Reserve’s developers opened a new chapter in aerodynamics. Now, the Californian brand aim to whirl up the aero segment with this innovative approach. Bye-bye, aero. Say hello to turbulent aero.
60 seconds faster over 45 kilometres, 17 watts savings, 30 % advantage over other aero bikes – the latest generations of high-end aero bikes keep boasting with increasing efficiency gains. The values are underpinned by illustrations of wind currents as they flow over Kammtail tubing profiles, aero deflectors, or low-slung, angled seat stays. But what does aerodynamic theory have to do with real world conditions in the peloton, on an Alpine pass or in the urban jungle? Not much, according to the Californian brand Reserve, who are breathing new life into the aero debate with their turbulent aero approach.
Welcome to the virtual wind tunnel
Most of today’s development work is done on computers. An airflow simulation software called Computational Fluid Dynamics (CFD) simulates and aerodynamically optimises the interaction of the frame, components, wheels, and rider. Digital test dummies ride countless kilometres in this virtual wind tunnel, computing various wind direction scenarios, climbing mountains, and plunging down descents. The integration of the rider exposes aerodynamic aberrations in the early stages of development, saving time and resources. It’s only the final designs that get validated in real and very expensive wind tunnel tests. But regardless of whether the airflow is generated by processors or turbines, it is laminar in most cases. A laminar airflow doesn’t factor in turbulence, it is easier to simulate, reproduce consistently, and make impressive simulations of. It has many advantages, but one decisive disadvantage: it only exists in the wind tunnel.
Real life is turbulent – not laminar
Where wind meets obstacles, turbulence occurs. Trees, houses, cars, and other riders turn the sleek, uniform airflow into a chaos of turbulence that is near impossible to simulate. Instead of a laminar flow, you get turbulent flow. In order to simulate this kind of flow, you need huge amounts of computing power on the one hand, and reference data from the real world on the other.
So far, wind tunnels haven’t been able to simulate real world conditions very accurately. Cornering, other riders, and turbulence aren’t taken into account. The results of aero tests can hint at the potential aerodynamic optimisation of components, but they must be verified in practice. Now, the boys and girls at Reserve have stepped in to redefine aero testing.
Will turbulent aero be the new standard?
Using a modified scooter for their measurements, the Californian brand collected wind resistance data for different locations and scenarios. The aim of the exercise was not to measure absolute wind speed, but rather the difference in turbulence between the sensors. Based on this data, the folks from Reserve purposely disturbed the virtual airflow in the software. The goal was to simulate the turbulent conditions of the real world on the computer. It’s all quite nerdy, but they didn’t stop there. Before components make it out of the virtual wind tunnel onto the road, they get verified in a physical wind tunnel. A design optimised for turbulent air flow needs a wind tunnel that can simulate turbulence. To this end, the developers rented a special system that engineers usually use to test the aerodynamic properties of architectural models. It consists of three tower-like structures, which are placed in front of the turbines to produce the desired turbulence.
Watts the point?
Current aero designs are optimised for scenarios that are hardly realistic in everyday life. Who rides on a straight, windless route for one hour at 45 km/h? Besides that, different manufacturers use different development and testing parameters. The resulting statements regarding watt savings and efficiency increases are difficult to compare. Ultimately, you end up with ten different aero bikes that are all more aero than the other, robbing the industry of credibility.
Reserve think of turbulent aero as an ongoing project. They’re striving to set a new standard in aero development. A common foundation that makes aero concepts more suitable for everyday use and optimisations more comparable. In 2019, Reserve started their basic aerodynamic research together with sister brand Cerveló. With the launch of Reserve 52/63 carbon wheelset, the first result of this development partnership is now available on the market.
The Reserve 52/63 wheelset: design and specs
If turbulent aero conjures up images of wild looking surfaces or futuristic serrated profiles, you’re bound to be disappointed. At first glance, the wheelset looks rather inconspicuous. The rim depths of 52 mm up front and 63 mm at the rear suggest a promising aerodynamic performance and a certain susceptibility to crosswinds. The front rim boasts a stately internal width of 25 mm, paired with a 24 mm internal rim width at the back, spinning on DT Swiss 180 hubs. If you want, you can also opt for the more affordable 240 or 350 hubs from DT Swiss. The total package weighs in at a competitive 1,514 grams and, thankfully, it isn’t ruined by oversized decals. The only branding you’ll find is discreet banderols, in line with the valve. By the way, Reserve offer a lifetime warranty on all their wheels.
So far, so normal? Almost. If you take a closer look at the profiles of the front and rear rim, you will notice that the front rim isn’t just shallower, but also slightly bulbous. According to Reserve, this should offer better stability in turbulent air flow. They say the rear wheel has a different task, and therefore relies on a different profile. It’s narrower, deeper, less bulbous, and has been designed to minimise wind resistance. Due to its asymmetrical profile, the rim also sits a bit off from the cassette, which should make the wheel more robust and durable. So, there’s a division of labour. The front wheel is responsible for stability and safe handling, while the rear wheel provides aerodynamic efficiency.
Who can feel the difference?
Turbulent aero is a process. Reserve themselves don’t claim that it’s an aerodynamic quantum leap in relation to the current generation of aero wheels. However, the potential of the approach is evident not least in Reserve’s cooperation with WorldTour team Jumbo-Visma. After the women’s and the junior teams rode on Reserve wheels in 2022, the Californian brand have now also become the exclusive partner of Van Aert and company for 2023. Besides aspiring to have competitive wheels for all upcoming races, the cooperation will focus on the further development and testing of turbulent aero. We currently have a Reserve wheelset in for long term testing, too, and we’re putting them through the wringer on different bikes and in different scenarios. We’re yet to conclude as to whether we believe the approach delivers on its theoretical promise in the real world. We’ll keep you posted.
Arbitrary calculations of time saved on a fantasy track have lost their appeal. They have little practical relevance and lack credibility. The idea of creating a new standard with turbulent aero is understandable and correct. However, we’ll need more practical tests to assess the potential of this approach. If the developments stay transparent and the theory is underpinned by real-world results, turbulent aero might be the future of aero. If not, we could end up with even more confusion about virtual wattage and proprietary test standards.
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Words: Nils Hofmeister Photos: Mike Thomas, Steve Loughlin