I wouldn't be wearing a helmet if the strap was no longer holding my helmet on my head.

Anyway, join in the year long debate on helmets fuelled by M.Anderson (of Copenhagenize blog) who passionately believes not in wearing helmets:

http://momentummag.com/videos/mikael...r-bike-helmets

In the above thread, I was accused of being irrational, emotional, blah, blah, etc.