elcruxio

depends on how one differentiates crashes. majority are those where no head strike is present and then there are the ones where there is a head strike. Now, depending on what one considers to be the aim of the helmet, it can be very useful or not so much. if its for avoiding lacerations, local hair loss or superficial injuries it's fantastic (although in many cases a hat would suffice). If the aim of the helmet is to avoid serious injury/death it fares considerably worse. In a strike which would otherwise lead to death would leave the helmeted rider with a significant brain injury. It does not however help against most concussions since it does almost nothing against non linear strikes where the brain suffer a torsional injury. These are btw the most common sources of brain damage and not the linear strikes where helmets prove to be most useful.

So yeah. Situations where a _bicycle_ helmet helps (actually helps with staying alive and serious injury free) are quite rare.
And just to make sure, we're now talking about actual crashes and not just riding along. Riding around with a bicycle is so safe with regards to statistics that any kind of safety gear is really quite unnecessary (this of course depends on one's riding, some cycling types are more dangerous than others, hence protect yourself accordingly)

But if we take driving a car for example, in accident situations a seatbelt is almost always useful. Speed is irrelevant really because if you are driving faster than 10mph and crash, a seatbelt is going to be useful in preventing serious injury. It also makes it possible for further safety devices inside the automobile to function correctly. A airbag is going to be useless if you don't hit it. A protective chassis is going to be useful if you get thrown outside of it or bang around inside like a ping pong ball.
Let's take a rear ending where one has already braked enough to drop the speed to 20mph before the crash. What would happen with a seatbelt? probably nothing. Maybe a bit minor of brusing, if that. Without a seatbelt? Ever tried to swallow a steering wheel?

People who disagree with seatbelts and even mandatory seatbelt use are quite different from people who disagree with mandatory bicycle helmet use.

And by the way, who here is dissuading others from using a helmet if they choose to? I have yet to see one post in this new thread. Do quote one if you can find it. But I must say such kooks are quite rare even in this thread. What you will find if you use a bit of time are people who wish to maintain their autonomy on the subject of helmet use and also realize the potential benefits/drawbacks of helmets.