"The 'wind-slicing sound' of carbon fiber wheels revealed: the secrets behind the scientific analysis"

When choosing a wheel, the eye-catching 'whirring' sound of carbon fiber wheels often attracts people. Some people may find this sound a bit noisy, but when you accelerate, this sound of the wheel will add a sense of luxury to your car and bring more power, especially on some closed-design wheels made of carbon fiber materials.

So why are carbon fiber wheels always so eye-catching? While some other wheels are relatively quiet? Although this question seems simple, you will find complex principles hidden in it after careful consideration.
Strictly speaking, this sound is caused by "turbulent noise", which is a resonance effect. So how does this sound relate to the wheel rim height, carbon fiber material, and internal structure of the wheel?

To answer this question, some foreign media asked Josh Poertner, CEO of Silca, via email. As a professional aerodynamicist, Poertner, who has worked in the wheel industry for a long time, is very familiar with the "whirring" sound of wheels.
"The answer is pretty simple," Poertner explains. "First, the whirring sound is caused by resonance, but this is greatly affected by the manufacturing process, materials, and internal structure."
In simple terms, resonance is the phenomenon where the amplitude of an object increases at a certain frequency and wavelength. As Poertner explains, there is a "resonant frequency" at which the amplitude is greatest.

In general, the more surface area a wheel has, the louder it makes. This also explains why fully enclosed wheels make the loudest whirring sound, while higher-end wheels are the second-loudest. "Once the rim height is less than 40mm, there is not enough sidewall area to push enough air, so the amplitude and sound effect are very low," says Poertner.
In addition to surface area, the internal and external structure of the wheel also plays an important role, especially the tension on the sidewall of the wheel or the surface of a fully enclosed wheel. Poertner explains: "Fully closed wheels with no spokes inside, like the Campagnolo Ghibli, Lightweight Autobahn or Black Inc Zero, act like a large resonant surface with a low natural frequency, which is easily excited by ground vibrations, like a drum, moving air inside and outside to create sound."

Poertner also gave a few examples comparing the impact of different manufacturing techniques on the noise of high-end wheels. For example, the Zipp 808 wheels use a completely hollow rim design, while the Corima wheels use an ultra-light and stiff Rohacell foam core. Due to the presence of the foam core, the Corima wheels are much quieter because it prevent the resonance of the rim sidewall to a certain extent.

The use of carbon fiber materials can also affect the sound of the wheel. Poertner explains that high-end wheels usually use thinner and more layers of carbon fiber stacking, as well as a higher ratio of carbon fiber to resin, so the rim sidewall is lighter, thinner, and more resonant.

Disc brake wheels can reduce noise to a certain extent. As disc brake systems become more popular, manufacturers can use rubber or low-temperature resins that can enhance elasticity to make wheels, thereby increasing the damping coefficient of the resin itself and reducing noise.
In general, the noise of a wheel may reflect its quality, price, or market position, but with the development of technology and changes in materials, some high-end wheels can also become quieter. Superteam has also prepared wheels with various sounds and rim heights for riders to choose from. If you are interested, please contact us~