[SystemSafety] Bicycle Helmets

[Chris Hills]

Hi

 

My gut feeling is that many cycle helmets are not properly fitted.  Neither are they correctly worn on the head.   The full face motorcycle helmets encase the head, are less prone to incorrect fitting as it tends to self-centre (and has a lot more padding).   Also they protect to halfway down the neck.   

 

>From memory most of the scratches on my motorcycle helmets were not on the crown but on the sides.  An area where cycle helmets do not protect.  Also motorcycle helmets are smooth whereas most cycle helmets  have slots and holes in them for ventilation which can catch on things. 

 

Regards

   Chris 

 

 

From: systemsafety-bounces at lists.techfak.uni-bielefeld.de [mailto:systemsafety-bounces at lists.techfak.uni-bielefeld.de] On Behalf Of Mike Ellims

 

I suspect that this  boils down to a few simple things;

 

Helmets are designed to absorb a certain amount of energy, once it’s done doing that it can’t absorb any more and the impact is delivered directly though to the head. Kinetic energy being what it is, once the speeds go beyond a critical threshold wearing a helmet doesn’t make any significant difference;  1/2mv^2 rules – whether you like it or not.

 

It also depends on what you hit, hitting a flattish surface is better than hitting something with a hard edge such as the  curb.

 

It also depends on the sequence of events  i.e. hitting headfirst is not good, but hitting with a shoulder will absorb much of the initial impact. It also helps if you slide as energy is dissipated over a longer period of time.

 

Bike helmets are much like cars which are designed for the most statistically common accident, i.e. frontal impacts at 50 kph and side impacts at around 18 kph. This doesn’t mean the car will protect you in a collision at 150 kph (1/2mv^2 again).

 

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