Improving cyclist safety and confidence by enhancing stability and using simulations to reduce drag by 7 percent

Optimizing the Syncros Capital SL wheelset’s performance

In the competitive world of cycling, innovative engineering plays a crucial role, where marginal gains can be the difference between winning and losing. Radiate Engineering & Design AG (Radiate), a Swiss engineering consultancy, made a significant impact by collaborating with Scott Sports SA on the design of the Syncros Capital SL wheelset.

This project was supported by Radiate’s simulation-driven engineering philosophy, leveraging Siemens Digital Industries Software’s Simcenter™ software and NX™ software. Simcenter and NX are part of the Siemens Xcelerator business platform of software, hardware and services.

Emphasizing simulation-driven engineering

Radiate’s approach to engineering is rooted in a philosophy they call “simulation-driven engineering.”

“Simulation-driven engineering is at the heart of our development process here at Radiate,” says Frederic Poppenhäger, a partner at Radiate. “It means we move simulation technology to the beginning of the product development process.”

Radiate’s goal is to shift traditional development processes, emphasizing early-stage simulations to optimize designs before building physical prototypes. “For some of our customers, it’s quite a new approach,” says Poppenhäger.

By integrating simulations early, Radiate showcases the benefits to clients who may be unfamiliar with this methodology.

Photo by Scott Sports, Michal Cerveny.

Balancing aerodynamics and comfort

Radiate’s collaboration with Scott Sports led to developing the Syncros Capital SL, a wheelset designed for road biking with an emphasis on aerodynamics, lightweight design and structural integrity. “The wheel is called Capital SL, and it’s basically the second wheel developed with this method,” says Poppenhäger. Together with Scott Sports, they designed their first wheelset, Syncros Silverton SL, for mountain biking, which some of the sport’s most successful riders used to win world cups and championship titles.

Aerodynamics is a critical factor in road biking, where every second counts. This requires balancing speed with other performance aspects. “A great aerodynamic wheel is generally a fast wheel, but it also has to be comfortable to ride,” says Poppenhäger. “When designing high-performance wheels, there is often a compromise between optimal aerodynamics and weight. Aerodynamic wheels typically have a deep rim profile, which adds weight. Designing an aerodynamic wheel means finding an optimal balance between low weight, low inertia, low aerodynamic drag and rolling resistance while ensuring the rider feels secure and stable.”

Photo by Scott Sports, Maxime Rambaud.

Leveraging Simcenter for innovative design

One of the standout features of the Capital SL wheels is their monocoque construction. “The Capital SL is a one-piece, or what we call monocoque, construction, meaning the rim and the spokes are fused together into a single piece,” says Poppenhäger. This design enhances structural integrity and reduces rotational inertia, leading to better power transmission and substantial speed gains for riders.

“The uniqueness lies in the manufacturing process,” says Poppenhäger. “This wheel is manufactured in one single shot. The rim and the spokes are fused together in one mold, come out in one piece and after that, you can displace the flange and insert the bearings.”

This design not only enhances structural integrity but also reduces rotational inertia, contributing to better power transmission and substantial speed increments for riders. “We built the wheel to be as stiff as possible while also ensuring compliance so it can be used in all kinds of riding conditions, even gravel biking,” says Poppenhäger.

Using NX for design and Simcenter for simulations allowed Radiate to explore countless design iterations virtually, significantly reducing the need for physical prototypes. “When it comes to developing lightweight structures, we use Siemens products, including NX, Simcenter 3D Structures and Simcenter 3D Laminate Composites,” says Poppenhäger.

Leveraging Simcenter enabled Radiate to perform extensive simulations, ensuring the final design met the high standards professional cyclists require. “With Simcenter products, we created very reliable results for our geometries and structures and optimized our designs to meet, and sometimes exceed, the requirements set by our clients,” says Poppenhäger. “When we use a simulation-driven approach in designing something as old-school as a wheel, you get new opportunities.”

By running simulations, Radiate evaluated various rim shapes and geometries, optimizing for aerodynamics and structural performance without the immediate need for physical models.

Photo by Scott Sports, Michal Cerveny.

Achieving marginal gains

Cyclists are obsessed with marginal gains. “Every gram of weight saved, every percentage point of drag reduction is important in this sport, especially competitively,” explains Poppenhäger. However, performance cannot come at the expense of reliability, so an important consideration was ensuring the wheel could cope with the rigors of racing on uneven public roads or gravel tracks.

Radiate extensively tested the Capital SL wheel using simulations before moving to physical prototypes and wind tunnel testing. “Using Simcenter, we simulated all kinds of rim shapes and geometries before prototyping and going to the wind tunnel,” says Poppenhäger. This rigorous simulation phase involved almost 200 configurations,
generating over five terabytes of simulation data.

By employing artificial intelligence (AI) and machine learning (ML), Radiate optimized designs beyond human intuition. “Leveraging Siemens simulation tools guides you to a new structure that you wouldn’t come up with otherwise,” explains Poppenhäger. This approach allowed them to identify the most promising geometries for further testing and validation.

Radiate’s design reduced aerodynamic drag by 7 percent compared to similar wheels on the market. “You can feel the difference; although maybe 7 percent less aerodynamic drag doesn’t sound like much, in the world of marginal gains, it’s significant,” says Poppenhäger. “Even an amateur rider will feel the difference riding with this wheel compared to a competitor wheel.” This reduction translates into noticeable performance improvements for riders, especially in the competitive world of racing.

To demonstrate this at the highest level of competitive cycling, Team dsm-firmenich PostNL (a Dutch professional cycling team) used the Syncros Capital SL wheelset in the time trial stages of World Tour-level stage races in 2024. “This wheel is not just for the professional rider,” emphasizes Poppenhäger. Riders of all levels can experience the benefits of improved handling, stability and aerodynamic gains, making the Capital SL a valuable addition to any cyclist’s setup.

In the wind tunnel, Radiate could fine-tune the wheel’s performance, particularly focusing on crosswind stability. “We try to improve this by making the wheel less susceptible or sensitive to wind conditions at high yaw angles,” says Poppenhäger. This ensures the wheel remains stable and predictable in various conditions, enhancing rider confidence and safety.

Photo by Scott Sports, Michal Cerveny.

Creating a balance between aerodynamics and structural integrity

Radiate’s innovative approach to engineering, underpinned by their use of NX and Simcenter, was not only integral to the revolutionary design of the Capital SL wheelset but has also set a new standard in the cycling industry. The careful balance between aerodynamics and structural integrity, achieved using extensive simulations and rigorous testing, demonstrates the power of simulation-driven engineering. The 7 percent reduction in aerodynamic drag, though seemingly modest, offers tangible benefits even to amateur riders, emphasizing the importance of marginal gains in competitive sports. As Radiate continues to push the boundaries of what is possible with advanced engineering tools, the Syncros Capital SL wheelset stands as a testament to the company’s commitment to innovation and performance and their continued collaboration with Scott Sports.

Photo by Scott Sports, Michal Cerveny.