I work in an ICU. I see a lot of traumatic brain injuries--most from car and motorcycle, but a number of bicycle accidents as well. Many of these folks don't make it and the ones who do often have a lifetime of profound impairments and handicaps. Unless I were to see rock solid evidence that helmets cause more harm than good, I am going to assume that helmets absorb at least some of the shock to the skull and are therefore worth it. I often wish I could take people to work with me and show them what it looks like to be in a car wreck without a seatbelt or to crash a motorcycle without a helmet. I don't like wearing a helmet--I like the feeling of the wind and having one less thing to lock up or take with me, but there is no way I'll ride without one.