Professional cyclist Mark Cavendish's sprint to the 2011 world champion jersey got the aero wave rolling. The Briton rode the road race in Copenhagen with equipment borrowed from the time trial: a skin-tight one-piece suit, the holes in the road helmet closed by a transparent plastic cover, the frame of the bike aerodynamically optimised. Since then, even more aero helmets have been developed for road racing: They fulfil current safety standards, protect like normal cycling helmets, can be individually adjusted with strap systems - and are also aerodynamically improved. This year, closed helmets dominated the spring races for professional cyclists for the first time.
Are aero helmets just a gimmick or do they really offer an advantage? To get to the bottom of the matter, we tested eight road helmets trimmed for aerodynamics in the wind tunnel and compared them with a selection of conventional helmets of the same or similar shape. In a second test, we also measured the cooling performance of the helmets for the first time using a new test set-up.
The test results of these aero road helmets can be found below as a PDF download:
- Casco Speed Airo
- Casco Speed Time
- Giro Air Attack
- Kask Infinity
- Kask Bambino
- Lazer 21 with Aeroshell
- POC Octal Aero
- Specialised S-Works Evade
The comparison helmets for this test were:
- Giro Aeon
- Kask Mojito
- Lazer Z1
- Poc Octal
- Specialised S-Works Prevail
Variety of shapes
Manufacturers use various methods to optimise the aerodynamics of helmets. The brute force method is to plug the holes. This is how Poc does it. The aero version of the Octal model has a thin panelling that closes off the helmet's numerous channels, leaving an opening only in the forehead area. Lazer uses a similar method for its Z1 and Helium models - but the attached plastic cover can be removed, which makes the helmets very versatile. Casco, Giro, Kask and Specialized have developed special shapes to reduce the air resistance of road helmets. They are more compact and have smaller frontal areas than the typical, jagged road helmets. The targeted guidance of the air flow via guiding elements and openings is intended to reduce air resistance and still ventilate the head. With the Kask Infinity, a slider on the front of the helmet can be used to regulate the air supply while riding.
This is how TOUR:
Aerodynamics
The aerodynamics test was carried out in the GST wind tunnel in Immenstaad. The test rider is the rigid TOUR rider dummy in a typical racing bike position, with the back at an angle of around 15 degrees. The total resistance of the bike plus rider with helmet is measured while the wind blows at 45 km/h over an angle range of -20 to +20 degrees. Summarised, the measurement gives the average drag power in watts. As the body remains unchanged apart from the helmet, the lowest wattage identifies the fastest helmet. The result is included in the overall score with 35 per cent.
Cooling
We tested the ventilation with a blower. The test head, which is filled with warm water and covered with a damp cotton cover, is mounted with a helmet in front of a fan and blown at a speed of 40 km/h. The temperature curve in the (circulated) water filling is used to determine the cooling capacity. We determine the cooling capacity via the temperature curve in the (circulated) water filling. This scenario simulates the cooling mechanism of welding evaporation. The cooling capacity is specified in watts. The higher the value, the better the ventilation. The result is included in the overall score with 35 per cent.
Weight
Determined for all helmets in size M. We award a score of 1.0 for helmets that weigh less than 200 grams. The result accounts for 15 per cent of the overall score.
Customisability
Top marks were awarded for twist locks, height-adjustable head straps and quickly adjustable locks. The result accounts for 15 per cent of the overall score.
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