AeroTaper Aerodynamic Spokes
Introducing the AeroTaper aerodynamic spoke, providing reduced wheel drag in crosswinds. This innovative design tapers in streamlined shape from a thin bladed profile located nearest the wheel rim, to a more round cross-sectional profile located toward the wheel hub. This patent pending aerodynamic spoke profile minimizes wheel drag when the spoke is positioned in the critical drag-inducing region of the upper wheel, where vehicle wheel drag is highly concentrated.
The AeroTaper spoke profile optimally reduces drag both near the wheel rim, and lower on the wheel where crosswinds are relatively stronger. Without this tapered design, the increased drag from crosswinds induced lower on the critical upper wheel surfaces largely offset any reduced drag from the bladed spoke sections when positioned higher in the critical drag-inducing upper wheel region.
In crosswinds, the effective wind impinging the spoke changes in vector orientation with wheel elevation. The wind profile diagram indicates that the direct headwind varies from at least twice the vehicle speed near the top of a wheel to near null wind at the bottom. However, the crosswind upon the wheel instead remains constant in speed with changing wheel elevation. Thus, the combined wind vector - when the spoke is positioned in the critical upper region of the wheel - changes from being directed nearly straight upon the spoke near the top of the wheel, to a more sideways orientation on lower sections of the spoke.
The AeroTaper spoke profile optimizes the cross-sectional spoke profile for this varying wind vector, thereby minimizing wheel-induced drag on the vehicle; the bladed spoke section providing maximum streamlining for the magnified headwinds impinging near the top of the wheel, while the round central section providing optimum performance against relatively stronger crosswinds having varying orientation where impinging lower on the upper wheel. And since the slower-moving lower section of the wheel contributes comparatively little to vehicle drag, the reversed vertical orientation of the spoke when positioned below the axle has little impact on overall vehicle drag.
The degree of tapering employed on the selected AeroTaper spoke profile can be optimized both for wind conditions, and will vary based on application. An AeroTaper spoke tapering more rapidly from bladed to round profile minimizes overall drag when used heavy crosswind conditions. An AeroTaper spoke tapering more gradually from bladed to round profile when used in light crosswind conditions maximizes aerodynamic efficiency. Likely a range of AeroTaper spoke profiles will prove useful to the road racing community.
The AeroTaper spoke is currently patent pending. Licensing inquires are welcome. Contact Null Winds Technology for further information.