The story of the HED CX - the original aero wheel

Absolutely the original aero wheel the HED CX completely revolutionised bicycle wheel design. Prior to its introduction in the late 1980’s all racing bike wheels, used by pro’s and amateur’s alike, featured box section aluminium rims and high spoke counts. Back then Steve Hed was an aerodynamics enthusiast who spent his spare time tinkering with high end model aeroplanes while also working as a composites engineer in the skateboard and waterski industries. But, he was essentially a cyclist at heart and he couldn’t help but think about how aerodynamics must have a huge impact on a bicycle. So, with the knowledge that he gathered from his past times and occupations he set about designing and constructing aerodynamic prototype wheels, in humble fashion, in his garden shed.


Steve knew that round, cylindrical objects performed really badly from an aerodynamic standpoint and he quickly identified that a tyre and rim essentially formed this shape when confronting airflow. Steve’s idea to counter this was to add a fairing behind the tyre and braking surface to help reduce air turbulence when it departed from the rim structure. The design was a success and Steve quickly went from making around 20 to 30 pairs, mainly for friends and local athletes, to turning out thousands.


The secret to the CX’s success was the cross sectional profile of the rim. Steve had identified that the most obvious shape for the profile, one that was similar to an aeroplane wing, that formed a sharp V-shape wasn’t really conducive to the slower speeds of a bicycle as the flat sides rendered it wholly uncontrollable during crosswinds.  Consequently Steve developed a more effective profile, one that altogether promoted a subtler silhouette and could be useable across a wide range of riding conditions. Initially, the cross section of the CX started with a 21mm wide tyre bed and angled brake track to help smooth the airflow from the tyre to the rim. The profile then flared out to 26mm wide before gradually tapering again to the rear of the cross section in a blunt, rounded fashion. This had the main benefit of keeping the airflow attached for a longer period of time even when the wind was coming at the rider from more aggressive angles. Better handling was the result allowing the deeper, faster rim to be ridden in a more predictable and safe manner in a vast number of riding applications.


With such an effective design, patents were quickly filed and granted. However, the lifespan of these was limited to 20 years so in the late 2000’s a large number of other wheel manufacturers began to utilise Steve’s rim shapes within their own designs leading to a burgeoning market. It now seems quite funny to hear of other present wheel manufacturers touting their wide, bulbous, blunt rim shapes as revolutionary as Steve actually pioneered these profiles over 30 years ago. With this in mind, the designers behind these new companies were almost certainly still at school when Steve was tinkering away in his shed, making wheels with these “modern” rim shapes.


Today HED are still very much the pioneers who move wheel design forward by conceiving and pushing new ideas. We currently own a vast number of patents for new aero rim designs, that differ from the original CX shape, that are now used in the current wheel collection. These latest rim profiles have again nudged wheel design closer to new frontiers allowing our wheels to be our quickest and most stable to date. The latest Vanquish series of wheels is the result of our new aerodynamic findings and real world riding experiences and coincides with ideas brought about by the change in direction of how bicycles are now being imagined. Our designs are once again pioneering and realising new ways of going faster, in turn rekindling the enthusiasm and enhancing the enjoyment within any ride.