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'Wearing a helmet could save your life'.
Fact or Fiction?
The truth is that there is no simple answer.
In some accidents
a helmet can reduce the risk of severe head injury.
However, the majority of head injuries
that result in death are caused by collision with other vehicles
(something that a bicycle helmet is not
designed to cope with).
Is it compulsory to wear a helmet?
Currently in the UK there is no legislation that places any requirement on you to actually wear a helmet.
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What can a helmet do?
Cycle helmets are only designed and tested to withstand an impact equivalent to an average weight rider travelling at a speed of 12 mph falling onto a stationary kerb shaped object from a height of 1 metre.
This is the equivalent of falling from your bike onto the road or the kerb edge.
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The importance of the size of the helmet.
If a helmet is to offer you any worthwhile protection it must be the correct size AND fit.
To understand why size and fit is so important, you need to understand how a helmet works.
Bicycle helmets are manufactured from expanded foam polystyrene.
Polystyrene is structurally rigid and can be moulded into virtually any shape.
However whilst being structurally rigid, it is a material which is easy to damage by crushing because it contains a high number of tiny air pockets.
The process of crushing absorbs energy.
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Any
moving object has energy.
To
stop an object from moving, this (kinetic) energy must be
removed by conversion to other energy forms. |
Cars have "crumple
zones": the front end is designed to concertina,
absorbing terrific amounts of energy.
But there is only so much energy that can be absorbed by this crumple zone, and at higher speeds (increased speed = increased kinetic energy) insufficient energy can be absorbed to adequately protect the occupants. |
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A helmet is designed to work in a very similar way, the polystyrene
acting as the crumple zone, lessening
the impact on the skull.
The helmet will make contact first and stop moving.
However, because the helmet can be crushed, the
head inside it is allowed to carry on moving for a short period
of time as it crushes the polystyrene.
Energy is absorbed in the process.
Because the skull is decelerated slightly more gradually, there
is a less impact between the skull on the ground AND the brain
on the inside of the skull.
Brain damage occurs if the impact
between the brain and the skull is too great,
i.e. if too much energy has to be absorbed by the brain.
The illustration below is designed to demonstrate
the effect of a helmet that does not fit correctly.
On the left, the helmet is not
a correct fit to the head.
On the right, the helmet touches
the head at all points.
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The
red areas mark the effective crumple zone. |
Try it on before you buy!
You should try on a number of helmets before buying.
The helmet should be close fitting all the way round.
Minor gaps can be filled using the soft foam pads generally supplied
BUT
Only the
polystyrene shell will absorb any energy and it is therefore
very important that this shell be as close a fit to your skull
as possible without it being uncomfortable.
Price
vs. Features.
• Cycle helmets can get a bit warm, especially in summer. More expensive helmets generally have more air vents and better internal airflow to keep your head cool.
• Comfort is a very important issue with helmets - if a helmet is uncomfortable, then you're less likely to wear it, and it is useless if you leave it at home!
• It is important that you don't mind wearing it. So, pay a bit more for a great design or colour. |
BEWARE:
The helmet only gives you limited protection. |
