> >What is a 'high quality helmet'? How is helmet quality measured?
>
> By the amount of money they take from your wallet. 
Seriously ask
> any helmet maker if their super expensive model protects your head any
> better than their bargain basement model and see what they say.
They'll say they don't! They'll be perfectly willing to admit that their
top-line helmets are no safer than their less-expensive models. Once you
get to the level of helmet where fit issues have been addressed (which
occurs around $40), you don't buy a safer helmet when you go up the ladder.
What you do (hopefully) get are-
#1: Better ventilation. High-end helmets are often subject to wind-tunnel
tests in a quest to improve aerodynamics and measure cooling.
#2: Better graphics & appearance. Higher-end helmets are screened better,
and the expanded polystyrene material is molded directly into the plastic
shell, rather than being glued & taped to it.
#3: Lighter weight. It takes a lot of work to get helmet weight down,
while retaining the same crash protection.
What you generally won't see is a manufacturer saying that one of their
helmets is safer than another, as the admission that something isn't as safe
as it could be is an invitation to lawsuits. However, it's entirely
possible (perhaps even likely) that a less-expensive model may offer greater
crash protection than a high-end one. Why? Because the manufacturer is
going to work at shaving as much weight as possible from a high-end helmet
until it can just pass the standards (tests) they're looking for. A
lower-end helmet, on the other hand, isn't going to go through such
scrutiny. If it passes the standard test, they're not going to go to the
time & expense of finding out how much tougher a test it will pass, nor will
they find out what they can remove or redesign and still have it pass.
--Mike-- Chain Reaction Bicycles
www.ChainReactionBicycles.com
