This summer I broad-sided a dog at 18 mph and hit the road hard enough to give me a major concussion. I also hit hard enough to begin a detachment of the retina of my right eye. I was wearing a helmet. I have no idea if the helmet kept me from more serious injury or contributed to it. There are those that would argue that the helmet hit the road when a helmetless head would not have reached the road, because my shoulder hit first. Hence the helmet contributed to the injury. There are others who might argue that the impact was strong enough that my head would have hit the road with or without helmet. I don't know the answer. Anyone who says they do has access to data that the rest us of should see. With that said, I'm still wearing a helmet, because I'd hate to think how much damage would have been done if those who made the second argument were correct. What I do know is that if I don't go down its not an issue. My focus is on riding in such a manner that I don't need the helmet.