How Well Do Popular Bicycle Helmets Protect from Different Types of Head Injury?
C E Baker1, X Yu2,3, B Lovell2
1HEAD Lab, Dyson School of Design Engineering, Imperial College London, London, SW7 2AZ, UK. c.baker17@imperial.ac.uk.
Annals of Biomedical Engineering
|September 18, 2024
Summary
Modern bicycle helmets show significant variation in protecting against head injuries. Rotational forces pose a higher risk, and while MIPS technology helps, it
Area of Science:
- Biomechanics
- Sports Engineering
- Trauma Research
Background:
- Bicycle helmets primarily address skull fractures and focal brain injuries, with less known about diffuse brain injury (DBI) protection.
- Real-world cyclist head injuries include both focal and diffuse brain injuries, necessitating a broader understanding of helmet efficacy.
- Current helmet standards may not fully capture protection against all injury types, particularly DBI.
Purpose of the Study:
- To evaluate the protective performance of modern bicycle helmets against skull fractures and diffuse brain injuries under simulated real-world impact conditions.
- To investigate the influence of helmet technology (e.g., MIPS), price, and mass on protection against linear and rotational head injuries.
- To assess the variability in helmet safety across popular UK cycling models.
Main Methods:
- Thirty popular UK bicycle helmets were tested using a novel headform simulating human head properties.
- Impacts were conducted at 6.5 m/s onto a 45° anvil at four locations (front, rear, side, front-side).
- Key metrics measured included peak linear acceleration (PLA), peak rotational acceleration (PRA), peak rotational velocity (PRV), and Brain Injury Criterion (BrIC); risks for linear, rotational, and overall head injury were calculated.
Main Results:
- Significant variation in head kinematics was observed, with overall injury risk varying by a factor of 2.25 between the best and worst helmets.
- Rotational risk showed the largest variation (4.21 ratio), while linear risk varied by 1.76.
- MIPS (Multi-directional Impact Protection System) technology reduced rotational kinematics but not linear kinematics; its presence did not guarantee top performance. Helmet price had no significant effect on injury risk, but higher mass correlated with increased linear risk.
Conclusions:
- A substantial performance gap exists among modern bicycle helmets, particularly concerning protection against diffuse brain injuries.
- A holistic assessment approach incorporating both linear and rotational injury metrics is crucial for helmet design and testing.
- Consumers need clearer information on helmet safety performance to make informed purchasing decisions.
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