don't specifically know what happened in the accident, or if any other body parts were injured (im sure there were). but the doc told my cousin that a better quality helmet (im assuming safety-wise, not cost-wise) would've kept him alive, so therefore i can only assume that the primary reason for death was from the head trauma. but then again, i'm only speaking from my assumptions...and also keep in mind, this guy's only a doctor, not an engineer or quality control for shoei or arai....
but its a crazy thought at how those polycarbonate shells absorb more impact than my fiberglass one...
If this isn't a bs post, then the following....The doc likely never saw the helmet, nor would he be qualified to make any judgments about crash helmet performance in the least even if he did see them on occasion.
Fiberglass is used to save weight, not for any other reason. Just as in any other use of fiberglass. It's stronger for a given weight than plastic resins with no support. Shoei and Arai have big racing marketing history, so they use and exploit lower weight materials and designs, because everything made for racing centers around weight and aerodynamic advantage, typically with less priority to performance. In the case of crash helmets, performance standards are just that, and materials are not something that is specified to pass the thresholds.
There is speculation that because car parts may give that crash helmets should be tested against concave surfaces, and that helmets made to withstand convex, or load concentrated surfaces will allow more g's in such events, but that is not likely when dealing with the physics of such a hit. The roof of a car may actually absorb some of the energy of the hit, and when the least resistant surface reaches it's stopping point, the next will take the energy. That means it will flatten out and the helmet liner will continue the braking process, with the head applying the force just the same.
Here's what Ed Becker of Snell said about various surfaces from some email correspondence:
"I don't know what initial assessment was made when the hemisphere was first invoked in standards but it and the flat were both in the first Snell standard issued in '59 and both came from BSI standards which were really the first consumer crash helmet standards anywhere. Although the idea seems appealing, ultimately, helmet testing is not really crash simulation. The hemi is not based on any commonly encountered road feature or grill ornament. We use it because it is simple and because we have a history of helmets tested against it that later proved effective in the field.
The reason to keep the hemisphere is that in crashes, heads and helmets can't count on striking flat impact surfaces only. By demanding that helmets meet test criteria for hemi as well as flat surfaces, we get good assurance that the same helmet will offer protection for every shape of surface between the two. A helmet that has done well against the hemi and the flat will do even better against a highway dot or a section of curbing.
In the spirit of this, at least one expert has suggested that we test against concave anvils selected to match the outer curvature of the helmet shell. Some measure of the flat anvil performance draws on shell characteristics. With concave impacts, we would eliminate the effects of the shell so the test would effectively dictate impact liner behavior. Once the designer had solved the concave impact requirements, he could then optimize liner thickness and shell stiffness to meet the hemi impact requirements. If the helmet could meet both the concave and hemi (convex) it would surely do even better against the flat. The directors were impressed with the concept but decided against it. The scheme called for the degree of concavity to match the helmet curvature but it didn't seem right to let the helmet choose the impact surface. I was glad not to have to mess with it mostly because we would have needed several sets of concave anvils each of which would have been much more expensive to machine than a simple flat.
There are more ways to go off a bike than anyone could anticipate while we get only a relatively few tests on which to base our judgments. The procedures are set to encompass a broad a range of potential impact surfaces in the severest impact configuration and at the severest impact velocity we think manageable. Some think our standard pays too much attention to the hazards inherent in load concentrating surfaces. But from COST 327 and from ITARDA data from Japan, that seems to be where the fatalities are occurring. Maybe because other standards aren't paying enough attention. Right now, though, we do have a good indication that helmets prevent brain injuries, not always but often enough that every motorcyclist ought to wear one. And often enough that I'd hesitate to tinker with the balance between the flat and hemi anvils in the “hope” of getting an improvement.
The reason that many EC qualified helmets do poorly in Snell testing is that the helmets might not handle the load concentrating anvils, the hemi and the edge. In Snell type testing, we see the helmet wall crushed completely before the impact is over so that the remainder of the shock is transmitted directly to the head form. The reason that many Snell qualified helmets may not do well in EC type testing is because of the more stringent flat anvil impact criteria. ECE 22-05 invokes the head injury criteria in addition to a peak g limit. Because of other differences in the standards, however, it looks as if Snell and EC 22-05 may be compatible for sizes XL and greater. There's no doubt that they diverge pretty starkly as head size gets smaller.
The real issue with helmets though, is, eventually, you get the protection demanded in the standard and not much more. Europe is looking for lesser protection from load concentrating surfaces so their helmets have trouble against Snell's hemi and edge. Snell has set conservative criteria for evaluating flat anvil performance but Europe's are even more conservative. The upshot is Europeans may get a moderately softer bump for a less severe impact but they may be at greater risk in a more severe crash or against a more hazardous impact surface. People with Snell or BSI 6658 type A helmets, conversely may get a moderately harder bump but may also have an advantage in more severe impacts or with load concentrating surfaces.
Since we believe that this moderately harder bump is still well within safe limits, and we've got a few studies indicating that adults and children do well wearing bicycle helmets qualified with the same 300 G criterion, the difference seems to favor those wearing the Snell qualified headgear.
The hemi doesn’t necessarily prejudice the standard toward or away from particular shell materials. Fiberglass may delaminate but polycarbonates may split or, in some cases, fold-in past the point where resistance to further flexion starts to diminish. I think the advantages one may offer over another are largely economic. You can build Snell qualified helmets with either so the choice will depend on production volumes and on labor costs versus tooling costs."
And here's what Becker says on the subject in his reply to Motorcyclist Magazine regarding the data from the COST 327 European accident study data and road hazards:
The COST 327 report, the same European study mentioned in the article, goes further. It suggests that this number will be much larger than 25% and the resulting hazard much greater than mere flat impact imposes. Their crash study indicated impact surfaces as follows:
“A round object was the most frequently struck, 79%, and the severity of injury was fairly evenly distributed. An edge object, for example a kerbstone was the least likely to be struck, 4%, but the most likely to cause a severe, AIS 5, injury. A flat object was struck in 9% of cases but was the least likely to cause an injury.”
The immediate conclusion is: the asphalt slab testing is, at best, incomplete. Impacts against flat surfaces will not tell anyone all they need to know about protective performance. Flat impacts are not the whole story and, if the European data is good, and I’ve got no reason to doubt it, flat impacts may be the least important crash consideration."
"Frequently, when a rider spills onto the pavement, he will not be able to maintain a controlled slide while his cruising velocity gets scrubbed off. If he gets even a little out of shape he’ll start to tumble and sustain multiple strikes to all his extremities. His helmet may need to manage a succession of impacts. And there’s also no doubt that if he goes off his bike and strikes something less friendly than flat pavement, for example: a vehicle turning left across his right of way, even that first impact by itself may be considerably more serious than any eight foot drop could ever be."
According to the Hurt Report:
Over eighty percent of riders with head injuries, were either not wearing a helmet or it came off (Hurt, 1981).
Here's a diagram from the COST study data that shows the areas of the head most likely to be impacted:
The severity of the impact energy used in Snell tests also requires a greater coverage area than any other standard, even when the test lines cover less area, and especially at the edges where the integrity is most compromised by the impact energy.
Snell has revised the 2010 standard to be more in line with ECE equivalents, with a reduction to 275G peak, and headform weights to correspond to new data that correlates head size to weight so that the divergence in HIC values will be negated. So, Snell helmets will still give the additonal range that is so valuable, while also keeping in line with the threshold values used by other standards, which should ease industry trade concerns over building different specs to sell in different regions and the loss of profit margin over the issue for manufacturers.