Written by Aerodynamic Testing
Aerodynamic testing of different high-performance helmets
Introduction
An evaluation of the different helmet aerodynamic efficiency was performed on the 16th of June 2022, in Bilzen, Belgium with a temperature of 25.3 ºC, a humidity of 50 %, air density of 1.189 kg/m3. Two UCI Continental cyclists from X-Speed United performed 3.5 km tests with different helmets. One was using a Scott TT bike, and the other was riding a Giant TCR road bike (riding on the hoods). Each helmet did at least two runs with helmets 1-3, and one of the athletes did four tests with helmet 4.
Methodology
Tests were conducted at speeds between 35-42 km/h, at a power output that allowed the athletes to maintain their position through each run (between 240-290 W), and allowing for repeatability of the tests without accumulating too much fatigue.
Both athletes were weighted before the tests with their complete equipment, and an analysis of the tires used was performed to assess rolling resistance. Moreover, athletes were using Notio Konnect® aerometers are placed on the handlebars to measure wind speed and evaluate aerodynamic drag.
From the 3.5 km test segments, 2.5-3 km of each test was used to obtain the aerodynamic drag of the athlete. The reason is for eliminating initial and final variable readings from the Notio. Furthermore, post-analysis was performed on Golden Cheetah to calibrate each run according to the Notio Konnect® guidelines for conducting aerodynamic tests and evaluating variations between configurations. It was considered that drivetrain efficiency was 100 % in the calculations.
Results
The results show that helmet 1 was faster than all the other helmets. On the road bike, the athlete obtained a CdA of 0.278 ± 0.0021 m2 with helmet 1, and lower than the 0.281 ± 0.0021 m2 and 0. 282 ± 0.0033 m2 with helmet 2 and the helmet 3.
On the TT bike, the differences were more significant. The athlete obtained a CdA of 0.235 ± 0.0028 m2 with helmet 1, and lower than the 0. 2405 ± 0.0044 m2 and 0. 242 ± 0.0028 m2 with the Kask helmet 2 and helmet 2 (these did not present statistical differences between them on both athletes).
As expected, all TT helmets performed better than helmet 4 (road helmet) on the road bike. On the road bike, the athlete obtained a CdA of 0.278 ± 0.0021 m2 with helmet 1 and a CdA of 0. 294 ± 0.0025 m2 with the Road helmet 4.
Discussion
Therefore, from this study, it can be concluded that helmet 1 is likely to perform better than the other two helmets tested both on a road bike and on a TT bike for most athletes. Moreover, its performance improvements are more noticeable on a TT bike than on a road bike. This could be explained because the wider TT helmet will slightly increase the frontal area on the road bike, reducing the performance improvements obtained from the decrease in drag coefficient obtained by using the Spiuk TT helmet.
In a TT position, the frontal area for the athlete will be the same when using the three different TT helmets, so the more comprehensive TT helmet will improve the flow around the shoulder of the athlete, reducing aerodynamic drag, and improving performance.
| Power output (300W) | Time | Time-saving (s) | Time | Time-saving (s) | Time | Time-saving |
| Helmet/Distance | 5 km | 10 km | 20 km | |||
| Helmet 1 | 6min52s | 0s | 13min44s | 0s | 27min28s | 0s |
| Helmet 2 | 6min56s | -4s | 13min52s | -8s | 27min44s | -16s |
| Helmet 3 | 6min55s | -3s | 13min50s | -6s | 27min40s | -12s |
Josh Teasdale's aerodynamic optimisation
This study was part of the aerodynamic optimisation of X-Speed United rider Josh Teasdale, leading to the UCI 1.1 Chrono des Nations where Josh finished in the Top 25.