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nikos force
01/09/2008, 15:10
full copy apo to periodiko BIKES ...



'' WHAT EXACTLY IS SHARP ''

predictably is is a contrieved acronym : safety helmet assessment rating programme . we favoured the pithier safety helment assessment test but no one seemed interested. All helmets sold in dealers have to pass the basic british standard or the equivalent european standard so are legally OK ...The sharp system aims to tell you ,which helmets are much better than ok by grading them from one to five stars ( five being the safest ).

and safest is a key word ,one of the controversial aspects of the sheme is that attempts to scientifically link its labatory crash tests to real world accident data . This means sharp can argue that if everyone wore a five stars helmets , 50 fewer of us a year would die from head injuries. In theory its a great idea . In practice its very hard to do .


SO WHAT DO THE RATINGS MEAN ??

in the original transport reasearch lab (TLR) report , the rtings related directly to the number of lives that would be saved if everyone wore that helmet . so if all of us wore five stars helmets 25 fmore lives would be saved than if everyone wore four star helmets ,which would save 25 more lives than three star lids and sso on .
however the latest explanation of how the rating are arrived at (called a test protocol) has not been made public and the department for transport (DFT)have yet to reply to BIKES questions.given that the sheme's first batch of results have been made public ,this seems odd .
Also ,whereas the original TLR report claimed 100 lives a year could be saved by everyone wearing 5star helmets, the figure has now dropped to 50 . no explaination has been given .Something has happened to the test protocol ,but the DFT wont tell us what .


SO ITS A GOVERMENT SHEME ????

yes it was originated ,paid for , and is the full responsibility of the DFT. They looked at 2 statistics 1) bike accidents account 18 per cent of deaths despite making up just one per cent of uk traffic . 2) eighty per cent of motocyclists killed, die of head injuries.If you are under pressure to reduse road casualties ,the conclusion is obvius : make them wear safer helmets.Hence sharp. The DFT also hopes the sheme will encourage manufactures to make safer helmets in oerder to get more stars and , presumably, more sales.


ITS SUSPICIOOUSLY LIKE THAT CAR ACCIDENT THINGY, NCAP. IS THERE ANY CONNECTION ??

Yes.ncaps success is getting drivers to buy safer cars nad forcing manufacturers to focus more on safety,undoubtebly encouraged the DFT to try sharp in the first place ,and is probably why the rating system is so simple.
But sharpstest are much more straight -forward THAN THE VAST RANGE OF NCAPS ONES.hELMETS WONt be getting extra marks for beeping fi your pillion hasn't got both hands on the grab rail .
However the ncap system was reviewed ,agreed and implemented by experts from dozens of european countries and is based on bog -standrd SCIENCE . SHARP IS PURELY BRITSh sheme ,some of the maths is adventurous, and the way in which test results are linked to star ratings has not been made public

nikos force
01/09/2008, 15:11
BUT WHAT EXACTLY ARE THE TESTS ????

The direct hits take place on five spots - forehead,left right side, top and back- and the impavt speeds are 13,4mph ,16,8mph and 19,1mph .the oblique impacts happen at 19mph and are aimed at both sides and at the chinbar. The direct hits are measured against a flat surface and a kerb ( even though the cost 327 report said that only 2% of accidents involve one ) There is no penetration test,where a spike is driven into the lid .

WHY ARE THE SPEEDS SO LOW???

Given that most of us all fall off cosniderably faster than 19mph ,the impact speed do seem low. however ,all helmet test experts agree that these speed are sensible because of the nature of majority of bike crashes.Their research shows that in most crashes we fall off at speed and hit our head on the road ,so tha downward force is no more than if you dived on your from standing up . the twisting force is potentially high because of the high speed ,but is usually limited by the low linear force.then we slide along ,scrubbing off a lot of speed before hitting something solid at an oblique angle.the other reason for the low speeds is that theres onl so much a glassfibre shell and 30mm of polystyrene liner can do -if you hit a solid object at 70mph no helmet will save you .


HOW DID THEY DECIDE THE PLACES TO TEST THE LID? SURELY NOT MANY PEOPLE CRASH ONTO THE TOP OF THEIR HELMET...
INDEED...in fact ,the top of of the lid gets hit in only 2% of crashes according to cost327. what sharp does is weight the results based on how common the crash site is .So if a helmet performs brilliantly on the top and poor on the side (which are the 53% of all cases), its score is likely to be very low

nikos force
01/09/2008, 15:11
HOW DID THEY GET THOSE RATINGS FROM THE LAB RESULTS???????

For scientists this is the controversial bit .there are 2 worlds we're looking at here.in lab world helmets are strapped onto tests rigs by people by people in white coats and verry carefully smashed up.results have lots of decimal places and helmets can be ranked in exact order. in real world motorcyclists wearing all sorts of helmets with all sorts of head sizes have all sorts of crashes at all sorts of speeds and produce very basic fatality statistics.the sharp system attempts to link these two worlds ,so that its test results will predict the accident statistics. its a great idea because it forces ratings to be weightened to match what actually happens in crashes .and the tests designed accordingly.so sharp should be a useful guide and push helmet design in the right direction.but the maths used to link those two worlds has to make several large assumptions , and even the scientists who came up with the modelling technique use words such as compromise and grey area a lot . so it could be wrong -probably not completely wrong- but certainly enough to question whether a 5star helmet really will be safer than a 4star helmet.

SO IS SHARP A GOOD THING OR NOT . SHOULD I PAY ATTENTION ?

The concept is undeniably fantastic - even helmet manufactures who have major issues with the test procedures agree to this point...sharo is genuinely trying to help us buy safer helmets , and gets manufactures to built even safer ones.So whats not to like ? its a bold idea and the DFT deserves credits for pushing it through when they knew any that scored badly would instantly go absolutely mental .
plus the decision to test a wider range of speeds than other standards is good . BUT the decision to keep the final test protocol secret is suspicious. why arent the helmet-buying public allowed to know exactly how the ratings are arrived at ? why werent the test protocol peer -reviwed ,LIKE A scientific paper would be , or at least published so other scientists could comment. here at bike we love the sharp idea but until we are allowed to fully understand those ratings ,our jury is out

bentouza
01/09/2008, 21:48
Συμφωνο με βρισκει το bikes.καλο φαινεται αλλα βλεπουμε οταν ανακοινωσουν λεπτομερειες..