While Reynolds has a quiver brimming with world-class race wheels, it's calling the 46mm its "signature rim depth." The reason for this is its exceptional versatility and optimal aerodynamics across every discipline of riding. From your ultra-fast weeknight crit series to the steepest of the summer hill climbs, Reynolds' new 46 Aero Carbon Clincher Road Wheelset has you covered. Its construction serves to beautifully illustrate Reynolds' latest generation of lightweight, durable, and aerodynamic carbon wheels.
The complexity of the Aero design is deep, but we'll walk through it together. To start, one needs to understand the prevalent ideology in aerodynamic wheel design, and to do so, we need to understand drag. Simply put, drag is the restraining force that acts on the wheel when its direction of motion is counter to the free stream of airflow. Now, airflow near the surface of a wheel is turbulent by nature, and when it comes close to the rim surface, it becomes a turbulent boundary layer. This is the start of two kinds of drag, skin friction and pressure drag. Currently, wheel makers are attempting to harness the turbulent layer, reattaching it at the rear section of the rim. The reasoning behind this is that the system reduces pressure drag, but in return, the wheel sees gains in skin friction. However, this is viewed as a compromising tradeoff, as skin friction has around a ten-fold lower drag value than pressure drag.
To maximize this turbulent system, we've been seeing builders create a constant, rounded edge at the spoke face. For those attempting it, it's been viewed as a leap forward in design. However, Reynolds finds it to be counterintuitive. We'll explain. You see, the science of aerodynamics has developed almost as a case of supply and demand. As aviation technology develops, engineers are forced to develop more efficient airfoil designs, and these designs take the shape of what's called a NACA profile — think of a stretched out tear drop shape. In recent years, though, some wheel designers have started to view the NACA profile as insufficient to the aerodynamics of wheels. The reasoning behind this is that while an airfoil only has what are called a leading and trailing edge, the rim's shape requires a trailing edge to double as a leading edge. Thus, we see the wide, rounded spoke faces of today. However, given that these systems rely on turbulence, Reynolds views this development as a step back from the proven designs of the airfoils that smooth turbulence. And this is just what the 46 Aero does with what Reynolds is calling, Dispersive Effect Termination (DET).
Starting at the rim bed, the 46 Aero features an ultra-wide maximum width of 26.2mm. As a clincher, this eliminates the drag-increasing balloon effect caused by a tire being wider than a rim. Now, the tire width matches the leading edge of the rim, creating less turbulence at the airflow's introduction to the wheel. The benefits to this design are fourfold — it delivers an aerodynamic benefit, it increases lateral rigidity, it also increases comfort, and it decreases rolling resistance. Moving down to the spoke face, the 46 Aero is shaped in a NACA-profiled, tapered V-shape that ends with a sharp trailing edge. This is where Reynolds starts to challenge the status quo. Basically, the Aero's shape actually smooths airflow over the wheel, and when that air passes the spoke face, it's easily reattached at the rear of the rim. So, the Aero places a focus on mitigating turbulence, not accepting it.
So, with DET, drag is greatly reduced. However, Reynolds wasn't content with just this. In fact, Reynolds views the aerodynamic engineering of wheels as a four-part structure. 1) The wheel must be lightweight, yet structurally sound. 2) It must reduce turbulent airflow in order to create a low-drag system. 3) The aerodynamic efforts cannot compromise the steering and handling of the bike. 4) The wheel must generate an aerodynamic advantage from its lift-drag-ratio. Not surprisingly, one wheel rarely encompasses all of these traits. In fact, we find that article numbers Two and Three actually tend to contradict one another — think of a disc wheel. However, at around 1505 grams, and with the lowest drag system on the market, the 46 Aero accomplishes all of the above harmoniously. But, to solidify this, let's get into requirements three and four.
This brings us to DET's most impressive characteristic, handling. In relation to the bearing, it's rare to have a real-world circumstance of a straight 180 degree head wind. In reality, you spend 95% of your riding time between 0 and 20 degrees of yaw with a wind angle anywhere from 0 to 100 degrees in relation to the bearing. Accordingly, DET places a focus at improving handling while side force is acting on the wheel. To do so, the DET rim shape pushes the center of pressure forward, beyond the center of mass (hub axle center), for a more stable steering force. For reference, the Firecrest's center