Originally Posted by
avole
I don't understand what you mean by your second sentence. You need to provide proof for that sentence with evidence, which, frankly, you'll be pushing to find.
If a person refuses to ride a bicycle under a mandatory helmet law, then they are 100% safe from a cycling head injury because they are not riding a bike. This use of a helmet, I agree, will do a fine job of preventing head injuries for those persons who give up cycling rather than wear a helmet.
No study is required as proof. Don't ride a bike and you won't get hurt doing it.