So, after using helmets of questionable background for a few months, I finally went out and bought the now famous Z1R. Only worn it a little bit, but so far, quite comfy... I have worn Shoei to this point, quite comfortably. The Z1R is definitely in its break in period but I think it is going to work out qute well. And, brand new, $90.... Not bad.... What's weird is that patterned ones had a weird fron design. I couldn't get the medium on my head and the large was too big... So, a medium ZRP-1....
I assume you mean the Strike? I went to look at those questionable-results-of-Motorcycle-magazine non-Snell helmets. Yeesh, I'm glad you like them, but I wouldn't bicycle in that helmet. Cheap, clunky, plasticky, rattly; even the liner material feels cheap.
The logic behind the study certainly seems to make sense, that a helmet that is too stiff is going to transfer more of the blow to the head. We shall see. And we are all entitled to our opinions. It is comfy, has pretty good noise reduction..... Hopefully I'll never need to find out the details of its protective value....
Netcraft stats confirm the most common endless arguments:
1. which engine oil is best
2. which helmet is best
3.speedometer accuracy
:cheers:
Quote from: RoadstergalI assume you mean the Strike? I went to look at those questionable-results-of-Motorcycle-magazine non-Snell helmets. Yeesh, I'm glad you like them, but I wouldn't bicycle in that helmet. Cheap, clunky, plasticky, rattly; even the liner material feels cheap.
Oh yea the questionable results ... :lol: ... BTW the same questionable study ranked the scorpion above the shoei/arai ... didn't they ...
In any case the mode of failure is what is pertinent. The fiberglass types dont yeild at all and hit them hard enough to yeild a little bit they crack ... poly carbonate flexes and bounces back, and the liner absorbs the energy. Good design, and basically you know the strengths of the materials and build it accordingly.
Cool.
Srinath.
Quote from: seshadri_srinathThe fiberglass types dont yeild at all and hit them hard enough to yeild a little bit they crack
Helmet makers call that
delamination. That's how the energy is distributed. :dunno:
Quote... poly carbonate flexes and bounces back,
Great for the helmet, but does your head
flex back into shape after a truck runs over it? :lol:
Quote from: GisserQuote from: seshadri_srinathThe fiberglass types dont yeild at all and hit them hard enough to yeild a little bit they crack
Helmet makers call that delamination. That's how the energy is distributed. :dunno:
Quote... poly carbonate flexes and bounces back,
Great for the helmet, but does your head flex back into shape after a truck runs over it? :lol:
I suggest you stick your head with a fiberglass helmet on it under a truck and see ... :lol: ... impact makes the helmet bend if its poly carbonate, the energy is infact dissipated wihtout delamination, the polystyrene absorbs the impact of your head and since that results in energy absorption from both sides that makes for a less severe impact. Fiberglass based helmets do not deform (remember the focus isn't bouncing back after deforming ) but the fact that at impact it doesn't deform ... making for all of your heads energy absorbed by the polystyrene. Make a harder impact and the lovely fiberglass delaminates with not even deforming the slightest. You dont really care about it flexing back, it is better for the thing to deform under light impact, and heck it should deform under higher impact too. Which is why the thing rated better in that test even when they hit it hard enough to break them. Elastic failure vs Plastic failure. Elastic is better ... No matter what Shoei and arai want you to believe.
Cool.
Srinath.
I thought the point was G force transfered to the brain. My understanding is that most of the head injuries that are fatal are caused by the brain bouncing back and forth.
If you hit the pavement hard what you really need is for the helmet to absorb the force and not your brain. We are not talking about a truck running over your head, but impact survivability.
On the snell side you have high impact multiple times at a higher G force and on the DOT side you have reduction of G force for the one impact.
And one important thing to note from the article is that no one wearing a full face helmet died from head injuries alone, according to the Hurt report. People who died had multiple injuries to other parts of the body that, in sum, resulted in death.
Quote from: crustyI thought the point was G force transfered to the brain. My understanding is that most of the head injuries that are fatal are caused by the brain bouncing back and forth.
If you hit the pavement hard what you really need is for the helmet to absorb the force and not your brain. We are not talking about a truck running over your head, but impact survivability.
On the snell side you have high impact multiple times at a higher G force and on the DOT side you have reduction of G force for the one impact.
OK ... no ... snell doesn't do multiple impact many times either ... They do an impact with a steel orange type object ... Now the fact is many helmets do not pay snell corporation to test and certify or fail their helmets - yes that's right ... Snell needs to be paid to test your helmet, they're not some voluntary safety organisation whihc will drop by at your factory and test away and give you the sticker if you pass all free of charge ... and the implication is if it dont have a snell sticker it means that it failed the snell test ... ha ha ... it just means it has not been tested by snell cos the maker didn't pay up snell. Essentially You call yourself a foundation and people sill start believing you are a voluntary benevolent organisation ... that can help people rebuild cities and get on with their lives after natural disasters like Hurricanes, earth quakes, forest fires etc ... While they are at it, they could get a decal that says they are sending a portion of the proceeds from every helmet purchased to victims of Motorcycle related hurricane disasters, and get themselves a website with an .org prefix ... Truth is ... they are a simple european corporation very similar to Enron and WorldCon.
In any case a high impact multiple time test ... no way any fiberglass helmet will pass that ... cos simply put with 1 high impact the fiberglass ones tend to delaminate and crack ...
I dunno if its true or not ... I heard the retail markup on (not sure if its shoei or arai or suomy) is like $200 ... and My friends at the dealer once told me that their markup on the SV 1K's they cleared out summer 04 (Team Charlotte Motorsports) for 5499/5999 were under 300 each ... in effect if a guy came in and bought an SV and a helmet and gloves and a jacket ... they made more $$ on the gear than the bike ...
Cool.
Srinath.
Snell is a nonprofit, and they need funds in order to do their testing. You pay for the test, the sticker, and the random sampling. The helmets cost more partly to offset the cost, and partly because it just plain has to meet a higher standard.
The DOT standard is based purely on voluntary compliance, because there is no money to independently test the helmets.
If you look at the roll bar wrapping on race cars, it's very hard and stiff material. If you hit someone over the head with Nerf, it doesn't hurt. If you hit them over the head with SFI padding, it hurts. Now, if you wrap the two of them around a steel bar, the one surrounded with Nerf will brain you, and the one surrounded with SFI padding won't. Yeah, the Nerf will transfer a lot less in the way of G forces to your head when whe haven't exceeded its capacity to absorb said forces. But it exceeds its energy absorbtion capacity fast. The SFI padding transfers more energy at low loads, but its absorbtion capacity is higher overall, so you don't get brained.
The Motorcycle article would have been laughed out of any peer-reviewed journal. One of these days, I'll have a sec to go through it and specifcally mark every jumped-to conclusion and unbased assumption in it.
The Hurt Report is unsurpassed in its look at the causes of motorcycle accidents. But it's not so useful for looking at helmet protection. For one thing, helmet use was a lot less widespread when the study was done. That's one of the very good things the study did - it debunked the myth that helmets interfere with your ability to avoid accidents. Helmet wearers were significantly less likely to get into accidents in the first place.
And because of that, and because no distinction was made between Snell or non-Snell, fullface or non-fullface, etc., helmets, it's not useful for looking at the protective abilities of various accidents. That study is now severly out-of-date, and a followup is desperately needed. One that looks at the construction and ratings of helmets in accidents!
The data is there. All road-racing organizations and the vast majority of track day sponsors require Snell-rated fullfaces. And people crash in races and at the track all the time. The data is there; it just needs to be compiled.
Anecdotally, I've seen plenty of crashes at high speeds in Snell helmets. And the people in question walk away.
They didn't write that report based on the hurt report. They tested them using a drop machine type thing and the only thing they did different from the snell test was that they dropped it on flat concrete/asphalt instead of a steel ball. They also dropped then on the edge of that same slab in another portion of the test. They tested the helmets to destruction and the fiberglass ones destroyed easier. What was worse ... in all tests the fiberglass helmets transmitted more of G forces to the sensors. Its a nerf wrapped around steel except the Fiberglass helmets are the ones that are that way. In effect the fiber glass ones transmit more G's to the head under light impacts, and they transmit more G's under heavier impacts and they break easier. I actually dont see where they are better. Yes I also know of people that have worn Snell helmets and walked away. I would like to repeat that same crash with a HJC or a Z1R or any other poly carbonate helmet on that same head. That fact that Arai and shoei keep bringing up is the worst type of anecdotal evidence I have seen ...
There are people here that have survived crashes in HJC's and other supposedly poly carbonate helmets. Honestly quoting someone's case of accident survival is just plain like quoting davipu (no offence to davipu).
Yea Snell is non profit. essentially that means after they pay themselves and the corporate swindling is done and their advertising is done, there isn't no money left over. That same token applied to Enron and World con - they are better than non profit, they were making a loss ... :thumb: :thumb:
Cool.
Srinath.
FWIW, a girl on another forum I frequent bought one for the track. These are her words in the Review forum there-
Quoteit's not that good. i haven't crash tested it or anything, and i'm sure it'll be ok in a crash, but it is not that nice to wear. the peripheral vision is terrible. i'm not sure how or why, but when i wear the helmet i feel like i'm peering out of a submarine porthole. i can see directly in front of me and that's about it. a little annoying, but i got used to it.
it's reasonably light... not too noisy. i don't use the vents but they look and feel really flimsy.
worst part though - the visor flies open when i turn my head to look behind me. there's not really a lock or ratcheting thing to hold it shut. that is pretty sucky.
otherwise... i think the helmet is okay for track riding and it was a really really REALLY good deal. i think my next helmet will be something else though
Quote from: pantabloFWIW, a girl on another forum I frequent bought one for the track. These are her words in the Review forum there-
Quoteit's not that good. i haven't crash tested it or anything, and i'm sure it'll be ok in a crash, but it is not that nice to wear. the peripheral vision is terrible. i'm not sure how or why, but when i wear the helmet i feel like i'm peering out of a submarine porthole. i can see directly in front of me and that's about it. a little annoying, but i got used to it.
it's reasonably light... not too noisy. i don't use the vents but they look and feel really flimsy.
worst part though - the visor flies open when i turn my head to look behind me. there's not really a lock or ratcheting thing to hold it shut. that is pretty sucky.
otherwise... i think the helmet is okay for track riding and it was a really really REALLY good deal. i think my next helmet will be something else though
That pertains to just a Z1R or to what make. The scorpio's are great ... as are a whole slew of others including HJC's.
Face sheild flying open was almost a feature on the shoei till about 5-6 years ago, in any case, street speeds are unlikely ...
Cool.
Srinath.
I have a Z1R but mostly because I have a pin head and that was the one that fit the best. It fogs up if your not careful, I have to usethe antifog stuff alot. Its cheap, I bought mine xxs on clearance for like $70. Vents are really flimsy and sometimes like to open on their own. Haven't had any problems with the visor flying open, but the visor in general sucks. Theres alot more glare than the HJC I've been wearing lately. It is what it is, a cheapo helmet. When I was teaching my lil bro how to ride he dumped my 350 with his Z1R on and whacked his head pretty good...didn't crack or anything little bit of a dent where he hit a rock.
See its not about the Z1R vs anything else ... yea a lousy liner, vents that are made of egg shells and a visor that wants to fly away ... Total crap no question ... I buy that, heck I have never even seen a Z1R ... I can buy that whole idea of crappy slap together type deal ... the overall discussion is about Polycarbonate vs Fiberglass based composite for the shell, or in general material that exibits elastic failure vs material that exibits plastic failure ... My whole point is ... elastic is better and intuitively I have known that for years ... The motorcyclist article just proves that ... and if you must have a helmet that costs 5-6 times as much as the Z1R did ... buy a schuberth ... Polycarbonate shell, and lovely 5 piece beautifully vented and fitted together internals ... I am personally leaning to a Fulmer or a Icon ... My fit problem is really going to determine what ... but I have a Bieffe GPR for now ... whihc is Kevlar and super hard material whihc probably is a plastic failure candidate but at higher stress levels than a fiberglass POS. The fit of the bieffe was just beautiful ... Cant argue with that IMHO - made for my head and face ...
Cool.
Srinath.
Quote from: seshadri_srinath... the overall discussion is about Polycarbonate vs Fiberglass based composite for the shell
Cool.
Srinath.
Was it? The article in the June
Motorcyclist also seemed to blur the distinction between a Snell VS DOT safety standard debate and a fiberglass VS polycarbonate comparo, drawing conclusions which conflicted with their own charts.
Gleaned from the article....
* Snell helmets delivered more G's per impact due to firmer EPS foam which is needed to survive TWO impacts in the same location as per Snell requirement.
* The Snell Scorpion polycarbonate delivered higher average G's than Seven of the fiberglass helmets.
*Three of the DOT fiberglass helmets delivered a lower average G transmission than the DOT Icon polycarbonate.
Oddly, motorcyclist blew the opportunity to subject the DOT polycarbonates to a double-impact test. Perhaps the findings wouldn't have advanced the editorial slant?
Now the follow-up article in the November issue is out and the
Motorcyclist crew doing a 180 deg switch in position. Now stiff shell (laminated) good and flexible shell (molded plastic) bad when optimal foam is taken into consideration. :P
Wow....I think people are taking the article for way more than what they are trying to say....
They simply wanted to debunk the fact the having a snell sticker on a helmet makes it better.
Sure some of the helmets(ZR1) are cheap and only DOT approved took a better impact, doesn't mean that that helmet is better in all conditions, or the quality of craftmanship is up to par.
The big thing that they emphasized is that the snell system of two hemispherical impacts on the same area is causing the manufactures to have to make too stiff of helmets to meet the requirement, and that on the street no one usually hits the same hemispehrical object twice(let alone even one hemispherical object once), meaning that the DOT approved helmets sometimes are better at taking on impact.
Here is my thought...sure a $400 helmet may not do any better than a $70 dollar helmet, so go buy a $200 helmet and spen the other $200 on better gear and some MSF courses and now your a better,safer rider. You will get far more out of that then a $400 helmet.
Quote from: GisserQuote from: seshadri_srinath... the overall discussion is about Polycarbonate vs Fiberglass based composite for the shell
Cool.
Srinath.
Was it? The article in the June Motorcyclist also seemed to blur the distinction between a Snell VS DOT safety standard debate and a fiberglass VS polycarbonate comparo, drawing conclusions which conflicted with their own charts.
Gleaned from the article....
* Snell helmets delivered more G's per impact due to firmer EPS foam which is needed to survive TWO impacts in the same location as per Snell requirement.
* The Snell Scorpion polycarbonate delivered higher average G's than Seven of the fiberglass helmets.
*Three of the DOT fiberglass helmets delivered a lower average G transmission than the DOT Icon polycarbonate.
Oddly, motorcyclist blew the opportunity to subject the DOT polycarbonates to a double-impact test. Perhaps the findings wouldn't have advanced the editorial slant?
Now the follow-up article in the November issue is out and the Motorcyclist crew doing a 180 deg switch in position. Now stiff shell (laminated) good and flexible shell (molded plastic) bad when optimal foam is taken into consideration. :P
OK The EPS in a fiberglass helmet isn't why it delivered more G's as per their article ... it delivered more G's due to the fact that the fiberglass doesn't deform letting the EPS do the work of absorbing the impact. Now the double impact for poly carbonates would have been moot ... because the hardest hit possible a single one left the fiberglass ones broken. Polycarbonates deformed and came back to shape ... only they were even left standing for the second hit ... whether or not there was going to be another ... A light double impact test yes may ahve had fiberglass do better ... as long as it was light enough to not break the thing ... :lol: ... and Icon wasn't the point or scorpion wasn't either ... that 3 of the fiberglass was better than this or 7 were better than that ... essentially ... the priciest sheite wasn't worth the added $$ ... and fiberglass wasn't the best material any more ... in the 60's agreed it was the best ... not anymore. FWIW ... the highest end helmets like what schumacher and the top GP and others wear ... are actually covered in the new Nov issue of Motorcyclist ... helmet shells are hard as a MOFO ... kevlar and carbon fiber dealios ... super super hard (BTW my BR16 and the GPR I have now are both kevlar composite - no fiberglass) and the EPS is replaced by a material called skydex ... Just that the current crop of helmets ... we have EPS in all of them, and the poly shells are just a shade better in those no matter what the impact is ... as long as its not 2 light ones in the same spot - if it is 2 light ones in the same spot ... then the fiberglass ones they tested - which ever one came out on top in that sub set is better.
Cool.
Srinath.
I think I'll just have my head bronzed. :P
That may actually be better than a shoei ... :lol: ... Chrome Dome ...
Cool.
Srinath.
Quote from: Gisser
Oddly, motorcyclist blew the opportunity to subject the DOT polycarbonates to a double-impact test. Perhaps the findings wouldn't have advanced the editorial slant?
And that editorial slant point - I missed entirely ... see I can see if they favored the shoei, or the Icon or the scorpion even in that aspect ... these companies spend Tons of $$$ on the full page and pull outs in the Rags ... it does work in their favor to talk these up ... Z1R - never have I even heard of them before that article ... so only way there is slant ... If I see that Z1R is paying up big to advertise in the mag in the next few months - whihc I haven't seen in the recent past ...
I however cant wait for the next gen of helmets ... In the mean time I am using my super hard Bieffe GPR ... and when I get my next gen helmet ... I will film the helmet fight ... hit the bieffe with the shoei and vice versa ... till one of them busts ... then I will hit till it gets destroyed ...
Cool.
Srinath.
Quote from: seshadri_srinath
And that editorial slant point - I missed entirely ... see I can see if they favored the shoei, or the Icon or the scorpion even in that aspect ... these companies spend Tons of $$$ on the full page and pull outs in the Rags ... it does work in their favor to talk these up ... Z1R - never have I even heard of them before that article ...
Cool.
Srinath.
The
slant was toward sensationalism. It wasn't enough to put forth the proposition that the minimalist DOT standard was actually superior to the highly regarded and rigorous Snell standard (the implication being that high-end name-brand helmets were less safe than Pep Boys' blue light specials) they also had to sex-up the article suggesting that the polycarbonate shell itself was superior to the hand laminated composites without any proof. That theory quietly backfired in their faces in the follow-up article where the flexibility of the polycarbonate shells are shown to concentrate impact force into a smaller area while the latest thinking in safety designs are shown to have stiff composite shells and soft liners which dissipate impact force over a broader area. This is diametrically opposed to the assumption made in the original article.
Snell is dead. That's the real story. Over-eager motojournalists cost magazine ad revenue. That's
the rest of the story. :P
I should be getting my new shoei rf-1000 in the mail tomorrow! I can't wait! Right now I have some cheapo helmet that is snell2000 and dot approved the brand is AFX it was only $65 off of ebay from dennis kirk, never really heard of them...
Quote from: GisserQuote from: seshadri_srinath
And that editorial slant point - I missed entirely ... see I can see if they favored the shoei, or the Icon or the scorpion even in that aspect ... these companies spend Tons of $$$ on the full page and pull outs in the Rags ... it does work in their favor to talk these up ... Z1R - never have I even heard of them before that article ...
Cool.
Srinath.
The slant was toward sensationalism. It wasn't enough to put forth the proposition that the minimalist DOT standard was actually superior to the highly regarded and rigorous Snell standard (the implication being that high-end name-brand helmets were less safe than Pep Boys' blue light specials) they also had to sex-up the article suggesting that the polycarbonate shell itself was superior to the hand laminated composites without any proof. That theory quietly backfired in their faces in the follow-up article where the flexibility of the polycarbonate shells are shown to concentrate impact force into a smaller area while the latest thinking in safety designs are shown to have stiff composite shells and soft liners which dissipate impact force over a broader area. This is diametrically opposed to the assumption made in the original article.
Snell is dead. That's the real story. Over-eager motojournalists cost magazine ad revenue. That's the rest of the story. :P
OK Fine sensationalism ... However I am not buying thinking any thing else of what you said is valid in this post ...
Why ... The about face IMHO isn't a real about face at all ... The super duper schumacher helmets aren't fiberglass ... they are Kevlar and carbon fiber ... the same material that my BR 16 was made of and the same material that my new bieffe GPR is made of. The huge difference is ... the harder material like CF or Kevlar exibits elastic failure as well ... Fiberglass doesn't ... It exibits plastic failure, as in it absorbs energy in the shell and deforms and cracks and delaminates. That has effectively been tossed out as worthless. The EPS material inside a Poly carbonate shell which also exibits elastic failure is far superior than the same EPS inside a Fiberglass shell which exibits plastic failure. If you want to have a shell that has a harder elastic failure do a kevlar shell and to take care of your melon ... you need a better material than EPS. Fiberglass helmets broke under the hardest impact and they transmitted more G's to the head than the Poly which didn't break ... I'd say they lose on both counts.
Cool.
Srinath.
Quote from: seshadri_srinath
OK Fine sensationalism ... However I am not buying thinking any thing else of what you said is valid in this post ...
Why ... The about face IMHO isn't a real about face at all ... The super duper schumacher helmets aren't fiberglass ... they are Kevlar and carbon fiber ... the same material that my BR 16 was made of and the same material that my new bieffe GPR is made of. The huge difference is ... the harder material like CF or Kevlar exibits elastic failure as well ... Fiberglass doesn't ... It exibits plastic failure, as in it absorbs energy in the shell and deforms and cracks and delaminates. That has effectively been tossed out as worthless. The EPS material inside a Poly carbonate shell which also exibits elastic failure is far superior than the same EPS inside a Fiberglass shell which exibits plastic failure. If you want to have a shell that has a harder elastic failure do a kevlar shell and to take care of your melon ... you need a better material than EPS. Fiberglass helmets broke under the hardest impact and they transmitted more G's to the head than the Poly which didn't break ... I'd say they lose on both counts.
* Please, it's delamination. Might as well use the appropriate terminology supplied to us by the magazine article. Broke implies failure and yet the Snell FG's are required to survive not 1 but 2 high energy impacts in the same area. Some FG's transmitted more G's than Poly's and some did not. That's already been established. The Z1R performed well partly because of its monstrous exterior dimensions which leaves the wearer looking like a space alien. :lol:
* Carbon fiber versus fiberglass
I read up. Carbon fiber has the highest specific stiffness of any commercially available fiber and very high strength in both tension and compression. It's impact strength, however, is lower than fiberglass. CF shatters.
Your CF Bieffe ( :lol: ) for example is combined with Kevlar to contain the pointy CF shards in the event of an overwhelming impact. :o
Fiberglass can also undergo more elongation than CF before it breaks. So much for elastic VS plastic failure ( :? ).
The Schumacher superhelmet may be CF but 1 of the other advanced technology prototypes mentioned in the follow-up article used a
highly rigid fiberglass shell. It's all about the liner. Of course, none of the superhelmets were molded plastic. :P
* Now, back to the contradiction.
Motorcyclist claimed that Poly's flex rather than crush and delaminate, and this flexing, far from being a problem actually lets the EPS do more of its job of energy absorption. How? They say it's because flexing allows the EPS to start doing its work earlier. :lol: Nonsense. I'll tell you what, the flexing concentrates the energy to a smaller area which delivers more PSI to that particular section of EPS in effect making the liner behave softer. The drawback is that the force of impact is similarly concentrated on a smaller region of the vulnerable skull. :o This is why I say that no one racing at a world class level does so wearing a molded plastic helmet. :roll:
Quote from: GisserQuote from: seshadri_srinath
OK Fine sensationalism ... However I am not buying thinking any thing else of what you said is valid in this post ...
Why ... The about face IMHO isn't a real about face at all ... The super duper schumacher helmets aren't fiberglass ... they are Kevlar and carbon fiber ... the same material that my BR 16 was made of and the same material that my new bieffe GPR is made of. The huge difference is ... the harder material like CF or Kevlar exibits elastic failure as well ... Fiberglass doesn't ... It exibits plastic failure, as in it absorbs energy in the shell and deforms and cracks and delaminates. That has effectively been tossed out as worthless. The EPS material inside a Poly carbonate shell which also exibits elastic failure is far superior than the same EPS inside a Fiberglass shell which exibits plastic failure. If you want to have a shell that has a harder elastic failure do a kevlar shell and to take care of your melon ... you need a better material than EPS. Fiberglass helmets broke under the hardest impact and they transmitted more G's to the head than the Poly which didn't break ... I'd say they lose on both counts.
* Please, it's delamination. Might as well use the appropriate terminology supplied to us by the magazine article. Broke implies failure and yet the Snell FG's are required to survive not 1 but 2 high energy impacts in the same area. Some FG's transmitted more G's than Poly's and some did not. That's already been established. The Z1R performed well partly because of its monstrous exterior dimensions which leaves the wearer looking like a space alien. :lol:
* Carbon fiber versus fiberglass
I read up. Carbon fiber has the highest specific stiffness of any commercially available fiber and very high strength in both tension and compression. It's impact strength, however, is lower than fiberglass. CF shatters.
Your CF Bieffe ( :lol: ) for example is combined with Kevlar to contain the pointy CF shards in the event of an overwhelming impact. :o
Fiberglass can also undergo more elongation than CF before it breaks. So much for elastic VS plastic failure ( :? ).
The Schumacher superhelmet may be CF but 1 of the other advanced technology prototypes mentioned in the follow-up article used a highly rigid fiberglass shell. It's all about the liner. Of course, none of the superhelmets were molded plastic. :P
* Now, back to the contradiction. Motorcyclist claimed that Poly's flex rather than crush and delaminate, and this flexing, far from being a problem actually lets the EPS do more of its job of energy absorption. How? They say it's because flexing allows the EPS to start doing its work earlier. :lol: Nonsense. I'll tell you what, the flexing concentrates the energy to a smaller area which delivers more PSI to that particular section of EPS in effect making the liner behave softer. The drawback is that the force of impact is similarly concentrated on a smaller region of the vulnerable skull. :o This is why I say that no one racing at a world class level does so wearing a molded plastic helmet. :roll:
They said delamination but they showed a Fiberglass helmet that had split ... it had a crack in it ... if you wanna call that delamination sure go ahead ...
Carbon fiber has higher modulus of elasticity ... and its impact strength is lower ... what exactly is impact strength in terms of physics. Shear ... and yea CF and kevlar are always used in conjunction, Kevlar is if I remember the material to resist shear. Also CF and kevlar helmets weight more than the fiberglass ones ... almost 2X ... the reason I beleive is because of the fact that it is much harder to work with and they cannot weave it into a thin shell. Fiberglass is great for that. Elongation is strain in physics, and higher strain before failure is not the definition of plastic failure. Elastic or plastic failure is defined by the criteria that strain disappears once the stress is removed = elastic, not is plastic and poly carbonate is elastic and fiberglass is plastic, well known fact. With CF/Kev blends ... depends on the mix I should say what the youngs modulus is and what the elastic vs plastic criteria is. BTW elastic in one zone of stress and plastic following that is also another of the physical properties of materials. Pull it to the elastic limit and its going to fully bounce back, pull it past that and it will acquire a "set". That would mean just CF has a lower youngs modulus than fiberglass but says nothing about plastic or elastic.
Flexing does not neccesarily concentrate the forces into a smaller area. There is a phenomenon called punching shear. That will concentrate it on the tiniest area. The materials that exibit shear failure will obviously be the most susceptible to it, the fact the fiberglass delaminates makes it very likely to shear failure and it does make this likely as well. The edge impact that caused the fiberglass helmets to break is also a clear case of shear failure. Poly's did not break in that test ... I dont think poly's are likely to concentrate the impact in any situation.
No one is wearing a Plastic helmet of course. Its poly carbonate and its entirely different from plastic and of course no one is wearing one of those either. Shoei and arai are all the "Racers" like to wear ... those 2 have had such a head start in the helmet business agreed in the 60-70's they were the best around but after better and newer manufacturers came up with better products, they have effectively misinformed the people through dealers and they have cut in the dealers on the action in large markup's and effectively conned the public. There is a wee bit of inside information here. The SV 1000's were cleared out last year by my local stealer, 5999 for the S and 5499 for the non S. In fact they went as low as 5299 for the last few non S's, they sold 55+ of them last year. The parts manager said they were making under 350 on each. If a guy came in and bought a SV and a helmet, jacket and gloves and they got him up to a shoei and added that into the financing deal, on a $500 helmet they made 250. jacket and gloves could add up another 100 and essentially they made more on the gear than the bike. If he bought a $80 fulmer, they made nothing ... maybe $10. Essentially that is some serious incentive. I'd ask you 1 simple question ... why are harley dealers such assholes ... simple, they dont care about bikes, they wanna sell you useless crap over and over and over ... chrome air cleaner cover bolt cover ... ride down the street and it falls off ... OOps ... gotta but another one ... same thing with shoei and arai. Jap dealers are even bigger assholes in some respects ... they'd sell a GSXR 1000 to a total 16 yr old newb, and sell him a shoei helmet cos he has such a high performance bike ... and besides it matches the bike ... he crashes it leaving the parking lot, and they go ooops ... yea you gotta get it fixed and need a new helmet there buddy ... Shoei and arai probably invented the modern helmet - of the ones left standing today ... but they have looooonnnng since abandoned true research and gone the harley way (whihc if you recall invented the motorcycle too - yea sorta of the ones left standing today )
Cool.
Srinath.