bike helmets are supposed to crack in half, so that your skull doesn't. the reason why a $200 brain-sieve costs $200 is mostly because of the research and design that went in to making an ultra-light, ultra-ventillated helmet that will still protect your head as much as any other helmet. and, i suppose, because of the advanced materials needed for such things. doesn't the atmos have a carbon fiber skeleton?

anyway, now's as good a time as any for some bike helmet safety lessons:

-put your helmet on. without buckling the chinstrap, shake your head. if it wobbles, it's too loose.
-is it over five years old? get a new one. light and air degrade the foam to the point where it won't do what it's supposed to--protect your head.
-has your helmet had an impact? no visible damage? get a new one. helmets are one-time machines, even if there's no visible damage. it's ability to protect your valuable noggin is comprimised.