[xxgreg]

I think the title is wrong - it should be:

"Why it makes sense to drive wearing a helmet"

Based on:

We can also approach it from the perspective of injuries per million hours from a 1996 Australian study looking at head injury risk before the beginning of any helmet laws:

Risk of head injury per million hours travelled

Cyclist - 0.41 Pedestrian - 0.80 Motor vehicle occupant - 0.46 Motorcyclist - 7.66