I am not for or against helmets, but you can die just as fast from a side impact. Say you get hit by a honda and it pinches your leg between your top tube and the bumper breaking your leg and severing your femoral arterie. You would die in fifteen minute. When the femoral arterie is severed you bleed out rether quickly.

In another scenerio. Say you get hit by a pick-up or suv in the leftside. The impact breaks three ribs ruptures your kidney and spleen. You die within the hour. The bile enters your system and you die. If you ge tmedical attentioon right away you will still end up living life differently. You can't eat spicey foods you suffer from diabetes and many other conditions from the irepairable organ damage.