In reply to goose299:
> Why??
> Climbing helmets are all rated to the same standard.
No - they all pass the same standard. The difference in performance can be considerable.
Ever wondered why construction helmets have a ridge along the top? It's because they have to pass a penetration test, which just so happens to take place where that ridge is. The test pointy cone effectively must not reach the line of the inner cradle (i.e. your head). If you put a ridge at the test point your helmet can be smaller, lighter, cheaper and still pass. If the test took place at another point, the helmet would fail. It's never as simple as assuming that because a helmet has passed a test, that they're all the same: it just means that the helmet can pass a very closely defined standard test.
The other thing is that shock absorption and resisting penetration are two very different characteristics, in opposition to one another. I've not looked at bike and climbing helmet standards and characteristics, but I'd be surprised if they were the same.
Post edited at 10:59