I think it's interesting to look at the population's protection choices for various activities and compare them to the choices made for cycling. I'm also interested in people's risk assessments for various activities.

Here's my risk assessment spectrum that includes some activities mentioned lately. Highest risk of head impact to lowest:

banging your head against the wall > American football > cycling on ice > me jogging on a sidewalk with many sidestreets/driveways > me riding a bike down the road @ 12mph > recreational ice skating > walking