On Sunday, September 13, 2015 at 6:41:45 AM UTC-7, Frank Krygowski wrote:
On 9/12/2015 5:00 PM, Phil W Lee wrote:
John B. considered Sat, 12 Sep 2015 08:54:40
+0700 the perfect time to write:


About 75% of all bicyclists who die each year die of head injuries.

I think you'll find (unless it's very different from the UK, which
seems unlikely given the common mechanism of injury) that it's 75%
that have a brain injury at the time of their death, which may well
have occurred anyway due to other injuries.
Not much point in keeping your head in one piece if you've bled out
anyway. And even a motorcycle helmet won't save your head if a heavy
truck drives over it, or even some much lighter vehicles. So the most
you can do is cite that 75% as an upper bound.

I suspect the origin of the overestimate was a propaganda statement that
"75% of bicyclist fatalities involve a head injury." At least, that's
the way I first saw it expressed years ago. (Sorry, no citation.)

That version may be literally true - as in, the dead cyclist may have
had his abdomen run over by a truck's wheels, and he also got a little
scratch on his head. But the phrasing was obviously intended to trick
the reader into believing that helmets might prevent something like 75%
of fatalities. And other helmet proselytizers missed the subtlety and
went for the straight-out lie.

Similarly, after the infamous Thompson & Rivara paper of 1989 claimed
that helmets prevent 85% of head injuries, another paper used that
number to claim universal helmet use would prevent 85% of American bike
fatalities. And astonishingly, that made it through peer review.
--
- Frank Krygowski

Helmets are designed to do one thing and one thing only. It was designed around the old coaster bike where you were trying to make an emergency stop you would stand up. That put your head about 2 meters above the ground. The helmet was designed not for a collision but for a sideways fall from that standing position.

This ALSO turns out to be the largest sized helmet that a cyclist can be convinced to wear. Unfortunately your brain inside your skull is not designed to make a stop as suddenly as a helmet is designed to prevent skull injuries.

The human skull is evolved to fracture at just short of the point at which concussion occurs. Protecting the skull beyond this point causes concussion or the tearing loose of the brain's moorings inside the skull causing damage both from the tears and the smashing into the skull at the opposite side..

While most concussions are relatively minor they can be deadly or they can result in what happened to me - severe memory loss and a type of seizure that leaves no memory of it occurring. So I totaled four cars without knowing why before the DMV pulled my license on suggestion of my finally discovered "real" neurologist. Most neurologists treat aging diseases and rapidly forget their training for other far less common neurology illnesses.

The other thing is that the aero shape of a helmet is a lever that can rapidly twist the head breaking the neck. Helmet designs adjust for this by making the back aero section much weaker so that a side blow easily shatters the helmet. Of course that means that the helmet cannot give the "benefits" of the frontal area of the helmet.

Helmet manufacturers are in between a rock and a hard place. The good helmets do are mostly in racing where the head strikes are generally mild and the helmet protects the head from friction injuries on irregular surfaces. This is especially helpful in motorcycle racing. This is the reason for the very hard shell.

Since sport riders generally are more experienced and more aware they very seldom have serious injuries except high speed descents. Occasionally they are not paying attention and can get a right-hook or get doored. None of these are protected by helmets.

And when you look at cyclist's deaths and injuries the majority are on cyclists 15 years and younger. Closer investigation shows very bad riding skills such as riding on the wrong side of the street.

We have a member of our riding group who has 8 year old twin girls that he has trained to ride correctly from a very early age. With them riding relatively very heavy mountain style bikes we'll go on 30 mile rides and these little girls are very difficult to stay with on the climbs unless you're in good shape. You won't see these girls getting in any accidents since they ride more professionally than most of the group.