interesting this thread came up again today. I bought a new (to me) mag -Motorcycle Sport & Leisure. It has an article on Sharp testing and centres on a visit to the Arai test facility in Holland.
Reading the article, three points stood out:
- Sharp testing is performed at specific points on the shell. These points are published, so if you're making helments, just add a little more material at those points and you're away.
- No testing is performed on the chin area - at all!!!
- Each point is tested once and only once.
In my (limited) experience of being a crash dummy, the chin and temple areas were smashed repeatedly on the road. This simple test isn't included in the Sharp test.
The article concludes with the statement that Snell rating with random impact points is the one that manufacturers fear most.