Quoted message said:In low speed single-vehicle accidents helmets may make some difference to probability of injury.
In collisions with motor vehicles moving in the same direction at normal urban traffic speeds that
difference is at best vanishingly slight. In head-on conditions or in traffic travelling at extra
urban speeds, it's an irrelevence.
This isn't guesswork, it isn't possibly dodgy statistical studies, it's just basic O level
Newtonian physics. E=MV^2, and no amount of faith in polystyrene beenies is going to change that.
Good post, although I understand that the test standard does assume a body weight loading of a
helmet, even if the weight used in the test rig is less then this. (Which is not to say that the
testing procedure has any real world validity). Even with a body weight loading what use if this if
one is hit by a very soild car wight 1000kg?
Other thoughts, it seems that even assuming that under a high load a helmet will absorb a percentage
of that load is suspect. At high loads a helmet will probabaly just fail catastrophically.
Similarly, just think how much energy it takes to squash a piece of foam compared with that to break
it in half. Most 'my helmet was left in bits' failures show little evidence of having absorbed a
compressive load. This is not helped by all the vents and so on that encourage the helmet to break
up - and possibly increase the rotational load which is a primary case of serious brain injury.
Given the available evidence it seems fair to say that below 20 MPH there is a 95% of surviving a
crash, above 40 MPH there is a 95% chance of dying. As you show all wearing a helmet does is move
these boundaries slightly so we can expect the 95% survivability zone to end at 23 mph and the 95%
fatality zone to start at 41.7 MPH.
Why is the Government so keen on helmets? Easy. If you are run down and an ambulance attends, and
you have any form of head injury, you will be taken to hospital. If you attend hospital you will be
recorded as having aserious injury. This means head injuries are vastly over represented in
attendances and these distorted stats are then used to justify helmet wearing. Now Central
Government has set targets to reduce 'serious' injuries. To me this means those leading to long term
disability, life threatening injuries and so on.
Now in order to reduce such injuries the most effective action would be to get cars to slow down
substantially (whatever the arguments might be about crash causation, no one can argue that the
higher the speed the more serious the consequences of any crash). However, such action is seen as
being a vote loser. Now here comes the clever bit.
Many hospital attendances involve cyclists with minor bumps and cuts that could probably be
prevented by a helmet - and these are recorded as being 'serious' injuries. Voila! get cyclists to
wear helmets and the rate of 'serious' injuries would fall and targets would be met, even though
just as many cyclists would be killed and left with genuinely serious injuries as they ever were...
Of course the other reason helmets are so popular with some is that they assume there will then be
no need to control the speed of vehicles and so on...
