[giantg2]

They are not flimsy, mnless you are buying some sort of uncertified junk (rare). There are several different rating agencies that test and rate the helmets. Wearing a helmet isn't foolproof, and one could certainly die if the impact raring is exceeded or if they suffered severe trauma to another area. However, studies seem to indicate a 60-70% reduction in head and brain injuries and about a 65-70% reduction in fatalities. Clearly they are a significant factor.