Wheel performance is determined by three factors: aerodynamics, rigidity, and weight.
The new Shimano Road wheel collection optimizes the balance of those characteristics based on specific applications like climbing, all-round performance, or high-speed scenarios.
Wheels unlike any other.
One pedal stroke, and you’re off.
To develop a wheel that advances crisply, responding to the rider’s pedaling force, that is, a wheel with excellent acceleration performance, we made efforts to achieve two elements: improvement of drive rigidity and reduction of energy required for acceleration.
It is already known that rigidity and driving force are inseparable. However, it was not known which of the following three elements relates to driving force: lateral rigidity, longitudinal rigidity, or drive rigidity. Accordingly, Shimano created multiple prototypes with different parameters and has spent about three years assessing them with a professional team.
It was the sample with improved drive rigidity that received positive feedback, such as “It travels smoothly” or “It runs fast,” from almost all riders. In other words, it was found that drive rigidity is most closely related to driving force.
The total weight plays an important role in running fast, but it is also true that the contribution to acceleration differs between 1 g in the center and 1 g on the outer circumference. If the outer circumference weight is reduced, the moment of inertia (i.e. inertia) becomes smaller. The smaller the moment of inertia, the less energy will be required for acceleration.
As a concrete example, let's compare C36-TL with the conventional product C40-TL. To accelerate from 35 to 45 km/h in 7 seconds, 788.5 W output is required on the conventional model. On the other hand, the new model requires only 781 W, enabling a 7.5 W reduction. As for the breakdown of 7.5 W, the outer circumference weight accounts for as much as 60%. In other words, the reduction of the outer circumference weight greatly contributes to the reduction of the energy required for acceleration.
We aimed to develop a wheel with good acceleration by reducing the inertia while ensuring the required drive rigidity. As part of such efforts, we sharply reduced not only the weight of the hubs and spokes as mentioned above but also the outer circumference weight (≈ rim weight).