On Tue, 10 Feb 2004 13:01:44 +1100, "Steve"
wrote in message :

This "conclusion" conveniently ignores the energy expended during the
plastic deformation phase prior to the breakup. The aim would be to absorb
as much energy as possible b4 breakup - if the energy level exceeds that of
course it WILL break. It has still reduced the impact energy on the head.

Fine - so the helmet goes into an unplanned failure mode at some
unknown point in its plastic deformation phase - in other words it did
not work as designed. I am happy to leave it at that.

One might as well suggest that since your suspension "bottoms out" on really
big bumps once in a while, you might as well have no suspension at all.....

So suspension irons out the triival bumps, but hit a really big one
and you'll get a big hit back through the arms? Hmmm, where have I
heard something like that before... ;-)

Guy
===
May contain traces of irony. Contents liable to settle after posting.
http://chapmancentral.demon.co.uk

88% of helmet statistics are made up, 65% of them at the University of Washington.