Bicycle helmets are designed to protect, but if you compete, this protection comes at a cost. Studies show that traditional helmet design will slow you down. Still, it is a good idea to wear one, and racing organizations require them. Luckily, there are helmets out there designed specifically for competition. They are known as aero helmets, and they make you faster.
Aero Helmet Defined
An aero helmet is a bicycle helmet that is optimally shaped to make you, the rider, more aerodynamic. The shape is rounded at the front, just big enough to cover your head, with a straight tail projecting from the rear. The vents are few in number. Studies have shown a direct association with increased ventilation and higher drag. For this reason, effective aero helmets have little ventilation. This combination of shape and absence of vent holes, lessens drag and results in improved performance.
Effective Design
Although the shape of most aero helmets are similar, some designs are more effective than others. A study conducted at the Institute of Movement Sciences tested three different popular designs. One helmet was the standard water-drop shape, another had ridges from the front to back, and the last had a curved, sloping tail. The study determined that in order to minimize wake and lessen air resistance, certain standards should be met. First off, the width should be minimal. The less surface area, the better. Next, the trailing edge of the tail should not be rounded. This creates more turbulence in the wake. Lastly, there should not be any ridges or recesses on the surface. Therefore, the most aerodynamic helmet was the traditional water-drop design.
Time Savings
Putting the aero helmet to the test during a time trial reveals how effective they really are. It has been reported that over a 40 km distance, 4 seconds can be saved by wearing an aero helmet, as compared to a traditional style. For competitors at the elite level, this provides a significant advantage.
Decisions, Decisions
Consider a number of factors to determine if an aero helmet is appropriate for you. Cross winds and hills negate any time saved. Proper body position is crucial. A strict aero position must be maintained at all times in order to reap any benefit. Also, aero helmets are significantly more expensive than traditional designs. Take all of this into consideration before making your purchase.
Safety Considerations
Aero helmets are designed for racing and should be used for just that. Protectively, they have been tested and proven safe, but the lack of ventilation increases the risk of overheating. For this reason, you should only wear them when necessary.
References
- The Engineering of Sport: Aerodynamic Performance of Cyclist Time Trial Helmets
- International Conference on Mechanical Engineering 2005: Aerodynamic Efficiency and Thermal Comfort of Bicycle Helmets
- 15th Symposium on Applications of Laser Techniques to Fluid Mechanics: Wake Characteristics of Time Trial Helmets using PIV-3C Technique
- Masterscyclingmag.com: Time Trial Equipment-Best Bang for your Buck
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