> 10X fewer fatalities per KM ridden than in the US). If you want evidence that biking without a helmet is perfectly safe - there you go

What is the rate for non-fatal yet debilitating head injuries?

Personally I wear a helmet biking around "safe" areas to reduce the likelihood of serious head injuries, such as those that might be incurred if another cyclist collides with you, or if you fall to the ground somehow.

Ski/snowboard helmets seem like a decent idea as well.