The type of bicycles most popular in America all have a very forward-leaning riding position, compared to Dutch bikes. If you get into a crash at speed there is a good chance you are going to be pitched over the handlebars. A good friend of my brother was in a coma for 3 months after crashing into another bicyclist, flying over the handlebars and landing on his head. An ex girlfriend had the same sort of crash, but she had a helmet on and managed to avoid brain damage.
On a Dutch style bicycle, a headfirst over the handlebars crash is nearly impossible because the riding position is completely upright, and laid back over the rear wheel.
Helmet necessity seems like more of a factor for the type of bike you are riding vs. cars. In all the cases where I've seen bike/car accidents, the person was wearing a helmet, and they were dead anyway.
On a Dutch style bicycle, a headfirst over the handlebars crash is nearly impossible because the riding position is completely upright, and laid back over the rear wheel.
Helmet necessity seems like more of a factor for the type of bike you are riding vs. cars. In all the cases where I've seen bike/car accidents, the person was wearing a helmet, and they were dead anyway.