Strange but true, The protective effect of bike helmets is much smaller than people realise, according to Cyclist.ie, the Irish national cycling lobby group.

Could it be that the helmets interfere with their iPods?

Kinda like seat belts - the improvement to survival pushes survival slightly above 55% and of those that are "saved" there is a trade off for those that are killed for having seat belts on.

We can have 40 to 50 percent of people survive a crash without seat belts

or

we can have 30% of the people saved by seat belts, but 10 to 30% of those that would have survived by getting ejected are now killed.

Safety is important, but blindly accepting something that statistics counter is foolish.