Originally Posted by
randyjawa
I found this explanation on another forum. I like the answer and it might help shed light on the OPs question...
"...It is good common sense based on independent engineering tests performed by scientific testing agencies not involved in the helmet sales industry. Generally, they are the ones imposing the recommendations for replacement to reduce liability insurance costs for manufacturers- it isn't the manufactuer necessarily making the recommendations."
So has anyone seen a report from one of these 'independent engineering tests' that supports this conclusion? The only report with which I'm familiar is one at the BHSI website. They cite a test by Snell of a 10 year old Bell Biker which had been well-used and was yellowed due to UV exposure. When tested it performed the same as that model did when brand new. But they still recommend replacement based on some design improvements made in the interim.
http://www.bhsi.org/biker.htm