A group in Sweden has tested 27 popular bicycle helmets to determine which are the safest on the market.
The test was conducted by Swedish insurance company Folksam and funded through a grant by the Road Safety Trust, a United Kingdom-based group that funds road safety.
Four of the helmets tested are available in the United States, and have been certified through a process that is more rigorous than the one used for the Swedish study.
The study included five physical tests: two shock absorption tests with straight/perpendicular impact, and three oblique impact tests. The tests were performed by Research Institutes of Sweden (RISE), which is accredited for testing and certification in accordance with the European standard, CEN. The CEN (European safety certification) standard is not as rigorous as the CPSC standard, and separate testing is needed for helmets to receive that little CPSC sticker found in all helmets sold in the United States.
Shock Absorption Test
In this protocol, the helmet was dropped from a height of 1.5 m to a horizontal surface, with a maximum acceleration of 250g. The helmet was impacted at two different locations — one at the top of the helmet, and one at the side.
For this series of tests, a helmeted testing head was dropped against a 45-degree inclined anvil with friction similar to asphalt (Bosch 40-grit sandpaper) at an impact speed of 6.25m/s. Two Hybrid-III crash-test dummies were tested to minimize variations, and the testing configuration used in the study corresponds to a proposal from the CEN Working Group’s 11 “Rotational test methods.” Computer simulations of crash tests were also conducted for each helmet, for all oblique impact tests.
Of the “Recommended” protective headwear listed below, VeloNews confirmed that the following helmets are available in North America with CPSC certification, indicating they met a more stringent standard than the European safety requirements:
- S-Works Prevail II With ANGi
- Bell Super Air R MIPS
- Bontrager Specter WaveCel
- Scott Vivo Plus
The safety level of a helmet was rated relative to the average test results for all helmets tested, by comparing with the median value for helmets tested. Since the most common brain injuries often occur in offset impacts, the three oblique tests in the protocol influenced the helmet testing scores to a greater extent.
To obtain the best overall ranking and receive a passing approval, tested helmets must have performed better than the median score for shock absorption and oblique impact testing. Scores were derived from the below formula where T1 and T2 are the relative results in shock absorption and T3, T4, and T5 are the relative results in the oblique impact tests.
(T1 + T2)/2 + (2* ((T3 + T4 + T5)/3)/3)
The helmets with the “Recommended” designation performed 18-76 percent better than the average for the helmets tested. The seven conventional helmets receiving recommendations have additional safety and protection features (e.g., MIPS or WaveCel) aimed at reducing rotational energy which may lead to concussions or other brain injuries.
Folksam indicates that their improved test method, including oblique impacts, was used to mirror a common bicycle accident where a cyclist falls to the ground, striking their head at an angle creating a rotation of the head, commonly resulting in a concussion.
The complete study can be obtained from the Road Safety Trust in PDF form.