Analysis of statistics from Australia, before and after the introduction of mandatory bicycle helmet laws in Victoria and New South Wales, shows that bicycle helmet laws reduce the number of head injuries experienced while bicycling, but they do it largely by convincing people to stop riding bicycles. From an overall public health perspective, then, they accomplish more harm than good.
This suggests the greatest effect of the helmet law was not to encourage cyclists to wear helmets, but to discourage cycling. In contrast, despite increases to at least 75% helmet wearing, the proportion of head injuries in cyclists admitted or treated at hospital declined by an average of only 13%.
Helmets for motor vehicle occupants are now being marketed and a mandatory helmet law for these road users has the potential to save 17 times as many people from death by head injury as a helmet law for cyclists without the adverse effects of discouraging a healthy and pollution free mode of transport.