Originally Posted by skye

Once again, science does not support the use of helmets.

From:
Bicycle trauma and alcohol intoxication.
Int J Surg. 2015 Oct 19. pii: S1743-9191(15)01278-9. doi: 10.1016/j.ijsu.2015.10.013. [Epub ahead of print]

...

In short, there was no difference in head trauma between helmeted and helmet-less riders.

Originally Posted by Harada et al

Information regarding helmet use (Table 3) was available for 89.7% (505/563) of the patient population. Overall only 26.0% (131/ 504) of patients wore helmets. Helmeted patients were more likely to be Caucasian (79.7% vs. 50.3%, p < 0.001) and to have an undetected BAL (89.7% vs. 59.9%, p = 0.005) compared to their non-helmeted counterparts (Table 3). In addition, the risk for a severe head injury (AIS Head >=3) was significantly lower in helmeted patients (8.4% vs. 15.8%, p = 0.035).