Gattonero wrote: mjr wrote:
Well, yes there is evidence, called "tests" and especially "real use". I know many people that are still alive right because their helmet cracked instead of ther head in a crash.
Oh no you don't. 1. If it cracked instead of crushing, it failed to work as tested. 2. The "saved" outnumber all head injuries by at least a factor of ten despite usage being less than a third. 3. You seem to have ignored the "significant" see Goldacre and Spiegelhalter's article in BMJ. 4. There's a whole sub forum for this discussion, so do you have anything more to say about recycling them? I stopped using years ago but still have two to recycle when possible.
Oh I'm truly sorry if I have used the wrong word.
But as usual, I am a man who is convinced by what his eyes do see, not by what does he read. Just go to races and see people crashing, if they weren't suing a helmet....
Do an experiment. Take something remarkably hard like a human skull and then coat it in something soft, say expanded polystyrene. Bang it about a bit.
Can you foresee any possible scenarios where the polystyrene breaks but the skull doesn't?
A cracked EN1078 hat shows the impact had more energy than an EN1078 hat can take without breaking (it's meant to compact, not to break, in order to absorb energy). It is not an indication that the impact had more energy than a skull can take without breaking.
The next assumption is generally along the lines of saying one must be better off in those instances where the hat makes the difference
between a skull-smashing whack and not, but it's not that simple. At impact energies that will smash a skull a helmet will generally fail in brittle fracture mode (i.e., cracking) very quickly and absorb very little energy.
A bike helmet is designed to mitigate minor injuries, mainly so a rider can get back on and finish their race rather than abandoning while feeling a bit dazed. Helmets are particularly designed to do this for low energy impacts, notably the vertical component of a fall to the ground. This is, of course, exactly the sort of fall that skulls have evolved over a few million years to resist, so they're pretty good at it. You'll be less uncomfortable
whacking your head in a helmet in a typical case, but chances of it saving you from a certain fractured skull are far, far lower than your wording suggests.
Often seen riding a bike around Dundee...