Bicycle Safety vs. Car Safety

From Austin Bicycle Helmet Law

Cycling SAFER than driving

The commonly used per mile metric is inherently biased against cycling since auto trips tend to be longer. Per hour is the most fair comparison.

A risk analysis company (Failure Analysis, Inc., now known as Exponent Corp.) did a study some years ago and found cycling to have about half the fatality risk of being a driver or passenger in an automobile; 0.26 deaths per million hours compared to 0.47 for autos

RISK equals DOSE times EXPOSURE

The frequency of bicycle mishaps that could be ameliorated by helmet use is low (the DOSE is low). Despite a low dose, I wear a helmet when I ride my bike because I ride a lot (my EXPOSURE is high).

People who ride infrequently, or few miles, have both a low DOSE and low EXPOSURE; therefore they have correctly determined that their RISK is low. Wearing a helmet cannot appreciably reduce their RISK.

Long distance cyclists, competitive cyclists and many commuters (like me) have correctly determined that their RISK is a bit higher, because their EXPOSURE is higher, even though the DOSE is still low. The risk is still very low, even lower than the risk of death or injury in an auto collision, but it is higher than for someone who pedals very little. Requiring people to wear a helmet that will not reduce their risk will have unintended negative consequences for cycling.