Originally Posted by
bikebreak
Agreed, one of the interesting take aways from the magazine article was that the official bike helmet safety standard was basically lifted from the motorcycle helmet standard. The standard is based on preventing skull fracture in a relatively high speed impact. The foam won't compress enough in a lower speed impact to protect the brain..
This is dangerous nonsense - you have the truth exactly in reverse. Cycling helmets are designed to take a MAXIMUM OF AN 11-15 mph hit, carrying the weight of the head only. Beyond this the shell will usually fail, after which liner compression no longer absorbs energy.
If you don't believe me, google for the snell etc standards. Or read this summary by a professional helmet engineer:
http://www.cyclehelmets.org/1139.html
Cycle helmets are specified by their manufacturers as meeting one or more of the international standards for this equipment. All of the standards test the helmet's protection of only a decapitated headform, (i.e. one with no body attached); and
all tests involve only low speed impacts. Impact speeds are less than 6.6 m/s (24 km/h or 15 mph), and in some cases, barely 5 m/s (18 km/h or 11 mph). Unlike seatbelt tests, helmet test standards do not realistically replicate serious crashes.
Helmets reduce the force of an impact only while the polystyrene liner is compressing.
Once the liner is fully compacted, a helmet offers no further protection and passes residual energy straight on to the skull and brain. There is no evidence to suggest that helmets continue to provide a reduced level of brain protection beyond their design limits.
When helmets fail, they do so catastrophically, rather than gradually, by breaking. The breaking of a helmet is not by itself evidence that it has provided useful protection to the wearer. It is common for cycle helmets to fail prematurely, before the polystyrene liner has been fully crushed. Indeed, very often helmets break without the liner compressing at all, perhaps because they have been subjected to oblique forces, not directed at the head, that they are not designed to withstand. If a helmet breaks without its liner compressing, it is likely that no more than superficial protection would have been afforded.
In cases of high impact, such as most crashes that involve a motor vehicle, the initial forces absorbed by a cycle helmet before breaking are only a small part of the total force and the protection provided by a helmet is likely to be minimal in this context
Having read the article: this has all the hallmarks of
PR planted bs - one suspects that a substantial amount of advertising is to follow. The journalist is either amazingly incompetent and has accidentally distorted source after key fact - it's no wonder the OP get a completely wrong impression of the impacts helmets are capable of taking - or something very unethical happened
Serious injury from rotation or linear effects is incredibly unlikely below the 11-15mph limit cycling helmets work at - people die when they get hit by cars at 40mph, not in 12mph wobbles. Anti-rotation is a great feature for heavy motorcycling and mtb downhill helmets, which are strong enough to be useful in dangerous collisions, but in 12mph foam beanies it's just a marketing gimmick to get mopre money from the suckers.
Oh - and something like 80% of the cyclists who have fatal head injuries also have fatal torso injuries. Because cars = made of metal = SPLAT if you get hit by one at 40mph.