Nuxx:4e2ee577$0$2540$da0feed9@news.zen.co.uk

Path: num2.nntp.dca.giganews.com!num1.nntp.dca.giganews.com!number.nntp.dca.giganews.com!border3.nntp.dca.giganews.com!border1.nntp.dca.giganews.com!nntp.giganews.com!goblin2!goblin.stu.neva.ru!multikabel.net!newsfeed20.multikabel.net!dedekind.zen.co.uk!zen.net.uk!hamilton.zen.co.uk!shaftesbury.zen.co.uk.POSTED!not-for-mail Message-ID: <4e2ee577$0$2540$da0feed9@news.zen.co.uk> From: Nuxx Bar  Newsgroups: uk.rec.cycling Subject: Re: Saved by her helmet Date: Tue, 26 Jul 2011 17:04:06 +0100 References:       Lines: 24 User-Agent: Mozilla/5.0 (Macintosh; U; Intel Mac OS X 10.7; en-US; rv:1.9.2.18) Gecko/20110616 Thunderbird/3.1.11 MIME-Version: 1.0 In-Reply-To:  Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Organization: Zen Internet NNTP-Posting-Host: d25c6ad3.news.zen.co.uk X-Trace: DXC=;\9=DUH;jkIg`4Y59;oSFLnok4Z\ On 25/07/2011 12:26, Greentable wrote: > >> Please can you explain how the helmet hit a hard surface, it was >> cracked in three places, and yet it absorbed no energy whatsoever. > > It's made of polystyrene foam, which absorbs little or no energy in > brittle fracture. A helmet that has broken has failed, they are designed > to absorb energy by crushing. This is tested with a rigid headform, > which is not in the least it like a human skull, and I know two > experienced expert witnesses in cycle injury cases neither of whom has > ever seen a helmet that has crushed as they are designed to do. > >> It would seem to me that the helmet most likely performed exactly as >> they are meant to do. The soft interior absorbing the energy of the >> impact. > > No, it failed. Any helmet that breaks on test, fails. Check the standards. > > You can check this out for yourself a bit by experimenting with > polystyrene foam packaging.

Why do you wear a helmet then, Guy?