Perhaps the problem was the D2, as many others have said, and not bike helmets in general.
New helmet - POC Cortex DH Vs TLD D3?
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^ +1... Sorry, I really didn't have anything else to add to this thread.
Again, read what I've already stated:
The terminology I used was incorrect. I should have used the term "transmissibility rate", not impact absorption. Because that's what is actually happening; the foam affects and reduces the transmission of impact force.
Because there are so many variables in regards to impacts, there's a bunch of different ways to calculate transmissibility rates. If you wanna learn some of the fundamentals of it do a google for "half sine shock pulse". It's the simplest way shock forces can be studied.
**edit: one of the most common ways to express a particular material's effectiveness against protecting a particular item is known as a damage boundary curve. Its a region plot of change in velocity versus acceleration**
Could it work that way? Absolutely. Why anyone would design it to work that way for a helmet is beyond me. (in packaging distribution, there are scenarios in which this kind of performance is desired).
Its not that they are underdesigned, its that the standards to which they are tested and approved were written long before DH as we know it existed. Hence the creation and approval of ASTM F 1952 (formally approved in 2009). It was designed to address just this issue, and to create a standard for which downhill helmets can be tested and approved.
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This is an EXCELLENT way of putting it.
Sorry if I'm not being perfectly clear, it's not exactly easy to compress several college terms worth of technical material into a few paragraphs in layman's terms.
Just cause they meet some standard doesn't mean they are appropriately designed. There are products that are cheaper, and do they job better. That sounds underdesigned to me.
Actually, the ASTM (or DOT, or EN, for those across the pond) standards to which helmets are tested are performance based standards. In this case, standardized levels of the impact force which a helmet should withstand. So yes, it is an indication of whether or not they are appropriately designed for their intended use.
And in this case, moto helmets and mtb/dh helmets are technically designed for different uses (or jobs as you put it), so providing they meet the standards for the use they are intended, then yes, they are appropriately designed.
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Agreed! They might be technically designed for different things, and I'm sure they meet those standards. I'm certainly not disagreeing with you there. I'm just questioning those standards, that's all. It only took one good knock on the head in an MTB helmet for me to see the light, just trying to help other people buy more appropriate protection, AND save some money at the same time
Like hacktastic said, for them to charge as much as Shoei or Arai helmet is just crazy.
The issue was the old standards to which they were tested - ASTM F 1447 (prior to 1999). In 1999, CPSC sidelined this standard with their own. The CPSC standard was essentially the same as ASTM F 1447, but tests helmets with a more severe (higher force) impact. Neither of these standards encompass impacts to chin bars (full face helmets).Agreed! They might be technically designed for different things, and I'm sure they meet those standards. I'm certainly not disagreeing with you there. I'm just questioning those standards, that's all. It only took one good knock on the head in an MTB helmet for me to see the light, just trying to help other people buy more appropriate protection, AND save some money at the same time
Neither CPSC standards nor ASTM F 1447 really encompassed the kind of impacts downhillers were seeing, even back in 2000.
Now, we have ASTM F 1952 - designed specifically for the severity of impact forces seen in downhill. It tests for impacts of greater severity than either ASTM F 1447 or CPSC standards. It also encompasses test methodologies for the chin bar, but it is not mandatory. From the standard:
"ASTM F 1952" said:
DOT standards and Snell standards are still the toughest out there. Exactly how ASTM F 1952 compares to them I don't know, I don't have the complete text of 1952 (FWIW you can read the Snell standards on their website: www.smf.org )
FWIW Snell M-2005 is the most severe of all tests designed for motorcycles, dirtbikes, bicycles, etc.
A lot more info can be found at www.bhsi.org
This thread is officially nerd neutered!
I do have to laugh a bit when the new astm standard is touted as THE appropriate standard for DH riding.....
Yet the actual test procedures and standards are not made public.
No one outside of the industry really has any idea what this standard requires, or what additional protection it may (or may not) provide.
IMO, the best standard for agressive use for MTB use is the euro standard for moto helmets, but of course you cannot purchase any of those helmets here in the land of 'MORE IS BETTER' and lawsuits.
Yet the actual test procedures and standards are not made public.
No one outside of the industry really has any idea what this standard requires, or what additional protection it may (or may not) provide.
IMO, the best standard for agressive use for MTB use is the euro standard for moto helmets, but of course you cannot purchase any of those helmets here in the land of 'MORE IS BETTER' and lawsuits.
What do you expect? Them to go around giving this stuff away? ASTM is a business. These test methods aren't gonna write themselves. They take time and money to develop and validate.
The same thing is true for Snell and Dot and EN standards, yet all of those are easily available to the public, for viewing, comparison, debate, external testing... If ASTM's model is to make money from simply viewing the standards...that makes me think that they have nothing to do with enforcing or testing for standard qualification (how some of the other companies bring in $$ for their documentation).
Either way, without ready access to said standard, you are spending more money for a product that you are simply told is superior... when in fact, you as a consumer do not even know what you are purchasing.
If ASTM is not themselves doing random testing of production items (to verify compliance), AND letting the consumer know exaclty what the product was teste 'to', then their standards and thus the 'clout' of their name is essentially useless.
Snell is a private non for profit and chooses to freely publish their information, and DOT is a gov't entity, so its pretty much mandatory for their regulations to be published.
It isn't ASTM's responsibility to enforce their compliance with their test methods. Part of that responsibility is handled by the CPSC (at least here in the states). In fact, numerous ASTM test methods have been incorporated into, or are directly referenced by, federal, state or local law. So in these instances compliance with ASTM methods is a legal obligation. Therefore, compliance with these standards is the responsibility of the manufacturer of a given product, not the organization that creates the standards.
I do agree with you though, I feel that there needs to be better explanations readily available to the public in regards to the standards to which items are tested, and what these standards mean. ESPECIALLY products safety equipment used in sports like mountain biking and motorcycle riding.
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hey guys in case you're intereted, in Montenbaik.com we did a test of the poc helmet.
google bar traslator is on the top right column
google bar traslator is on the top right column
I don't want to get into numbers (cause I don't have them all handy), but here are some standards cliff notes:
CPSC/ASTM 1447: Minimum standard to legally sell helmets in the US. Includes impact tests on round, curbstone, and flat anvils. Round and curbstone anvils from lower height. Flat from tall height.
Snell Bicycle: Same as CPSC/1447 but with increased drop heights for round and curbstone anvils.
ASTM 1952 (DH): Same increased drop heights as Snell. Increased rear coverage requirements. Chinbar strength requirement.
DOT: Suprisingly similar to ASTM 1952. Drops have to be performed twice in the same spot. Rear coverage not as strong. No chinbar requirements. Does include penetration requirements (dropping a steel spike to see if it punctures the shell).
Snell Moto: Drop heights increased. Chinbar requirements. More rear coverage than DOT. Also includes penetration requirements.
So how do they all compare?
CPSC vs ASTM DH: The DH helmet is going to have better coverage, be rated for higher impacts, and have a chinbar that's actually been tested.
DOT vs ASTM DH: The DOT helmet may be able to take an additional impact in the same place, but is not guaranteed to have any better coverage or even initial impact protection. DOT may not have a certified chinbar. DOT can provide additional penetration protection. (warning: opinion time: ever see guys riding around town on motorcycles with pathetic half-shell helmets? those are DOT approved. I don't like this standard at all for reference)
SNELL moto vs ASTM DH: SNELL helmet may be able to take an additional impact in the same spot. No way to say which will have a better initial impact protection. SNELL has a higher strength chinbar requirement (I think). SNELL has pentration protection.
Other notes:
Several DH helmets are rumored to pass DOT and/or SNELL impact requirements (two hits in the same spot from Moto heights/energies). No DH helmets pass the moto penetration tests though, so no one can actually claim to pass the standards. So these helmets have to stay as rumors even though they offer identical impact protection.
There is no Multi-impact standard and I have yet to ever see any manufacturer explain what they mean by multi-impact. In my opinion, no helmet should be used beyond 1 serious impact.
As for the OP: I really like what POC is tryning to do with their helmet. Just because I'm not sold on the multi-impact, doesn't mean I don't like the helmet. Haven't had a chance to check it out in person though. D3 is amazing in person if you have the cash. I'd have to go D3 myself simply because the POC isn't rated to go up to my head size.
CPSC/ASTM 1447: Minimum standard to legally sell helmets in the US. Includes impact tests on round, curbstone, and flat anvils. Round and curbstone anvils from lower height. Flat from tall height.
Snell Bicycle: Same as CPSC/1447 but with increased drop heights for round and curbstone anvils.
ASTM 1952 (DH): Same increased drop heights as Snell. Increased rear coverage requirements. Chinbar strength requirement.
DOT: Suprisingly similar to ASTM 1952. Drops have to be performed twice in the same spot. Rear coverage not as strong. No chinbar requirements. Does include penetration requirements (dropping a steel spike to see if it punctures the shell).
Snell Moto: Drop heights increased. Chinbar requirements. More rear coverage than DOT. Also includes penetration requirements.
So how do they all compare?
CPSC vs ASTM DH: The DH helmet is going to have better coverage, be rated for higher impacts, and have a chinbar that's actually been tested.
DOT vs ASTM DH: The DOT helmet may be able to take an additional impact in the same place, but is not guaranteed to have any better coverage or even initial impact protection. DOT may not have a certified chinbar. DOT can provide additional penetration protection. (warning: opinion time: ever see guys riding around town on motorcycles with pathetic half-shell helmets? those are DOT approved. I don't like this standard at all for reference)
SNELL moto vs ASTM DH: SNELL helmet may be able to take an additional impact in the same spot. No way to say which will have a better initial impact protection. SNELL has a higher strength chinbar requirement (I think). SNELL has pentration protection.
Other notes:
Several DH helmets are rumored to pass DOT and/or SNELL impact requirements (two hits in the same spot from Moto heights/energies). No DH helmets pass the moto penetration tests though, so no one can actually claim to pass the standards. So these helmets have to stay as rumors even though they offer identical impact protection.
There is no Multi-impact standard and I have yet to ever see any manufacturer explain what they mean by multi-impact. In my opinion, no helmet should be used beyond 1 serious impact.
As for the OP: I really like what POC is tryning to do with their helmet. Just because I'm not sold on the multi-impact, doesn't mean I don't like the helmet. Haven't had a chance to check it out in person though. D3 is amazing in person if you have the cash. I'd have to go D3 myself simply because the POC isn't rated to go up to my head size.
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Landcruiser, thanks for that info. 
isnt mtb helmets supposed to break and by that dont turn the head so much on the impact, i can see a moto helmet dont break as easily and hence turn the head more = bad?? Was some guy that was hurt really much because he used fullface in some urban dropping and the doctor said he had been much better off if he used regular mtb helmet.
I definitely agree that there needs to be a standard for "multi-impact".
And yes, ideally no helmet should be used beyond one impact. But the reality is that helmets are generally expensive, and the average downhiller can't afford a new helmet every time they crash. I don't know how many riders are aware that a helmet *should* be replaced after a hard fall (where you clock your noggin on the ground/rock/tree/etc), but I know that I'm guilty of this.
If you're interested in some of the technology behind the POC helmet, check out MIPS (Multi-directional Impact Protection System):
http://www.mipshelmet.se/
Not a ton of technical info, but a pretty good explanation of the concept.
jonKranked, if you are really interested i have access to the ASTM standard through work...
For that money, Fox V3 Carbon (one of the best looking helmet designs this year IMO) or Shoei VFX, maybe the best looking helmet ever. Unless you have a preference towards bike helmets... I've spent a lot of time in both, still undecided.
There's also the new Fox V3R carbon, which as I understand is being sold in Europe as a moto helmet but here as a bike helmet due to the fact that it cannot pass the double-impact penetration test described by landcruiser. As it was told to me, it can pass one of the two tests (snell and DOT), but not the other, not sure which one. I have never seen shell penetration be an issue for a bike rider though. In fact, the only time I've seen an outer shell really fail was on a moto helmet, being used for BMX of all things. No accounting for luck I suppose. Either way, the V3R is very light, looks pretty good, and could be a nice in-between for those who are torn on the ASTM vs. DOT debate.
There's also the new Fox V3R carbon, which as I understand is being sold in Europe as a moto helmet but here as a bike helmet due to the fact that it cannot pass the double-impact penetration test described by landcruiser. As it was told to me, it can pass one of the two tests (snell and DOT), but not the other, not sure which one. I have never seen shell penetration be an issue for a bike rider though. In fact, the only time I've seen an outer shell really fail was on a moto helmet, being used for BMX of all things. No accounting for luck I suppose. Either way, the V3R is very light, looks pretty good, and could be a nice in-between for those who are torn on the ASTM vs. DOT debate.
that would actually be pretty b!tchin' ... pm sent
A few thoughts, in point form:
- Price and protection are not related. All helmets on the market, within a given category, passed the same standard. In many cases, inexpensive helmets offer more protection due to greater thickness or fewer vents (the latter is more of an issue for road/XC helmets).
- Most people I know ride the D2 and most of them have had concussions on almost every decent head impact. Those who have switched to moto helmets (or other DH helmets, in some cases) have ceased to have that problem. Based on admittedly minimal and anecdotal evidence, I believe the D2 to be the least protective DH helmet on the market.
- It's important to separate helmet integrity from injury prevention. For example, a solid steel helmet could withstand any impact, but the brain inside would be liquified. A helmet gets mangled so you don't have to.
- I wear a moto helmet, but I avoid Snell-certified helmets. It's my opinion that the Snell test does not represent a typical, severe crash and leads to helmets that are heavy and much stronger than the head they're designed to protect.
- The Snell standard permits a higher maximum force on the head, relative to most other moto tests.
- The force required for a life-altering crash can be generated by the head free-falling from your body height while standing. Helmets don't have to protect against outrageous scenarios.
- I ride a Rockgard'n Blacklite helmet and it's been superb. It's cheap, light (for a moto helmet), and offers more frontal-impact stability than most moto helmets, which is vastly more than any DH helmet. DH helmets feel like toys after riding moto helmets.
- The weight of a moto helmet doesn't bother my pencil neck.
- The Kali Aatma looks like an interesting product. Have a look at: http://www.kaliprotectives.com/moto/
- Price and protection are not related. All helmets on the market, within a given category, passed the same standard. In many cases, inexpensive helmets offer more protection due to greater thickness or fewer vents (the latter is more of an issue for road/XC helmets).
- Most people I know ride the D2 and most of them have had concussions on almost every decent head impact. Those who have switched to moto helmets (or other DH helmets, in some cases) have ceased to have that problem. Based on admittedly minimal and anecdotal evidence, I believe the D2 to be the least protective DH helmet on the market.
- It's important to separate helmet integrity from injury prevention. For example, a solid steel helmet could withstand any impact, but the brain inside would be liquified. A helmet gets mangled so you don't have to.
- I wear a moto helmet, but I avoid Snell-certified helmets. It's my opinion that the Snell test does not represent a typical, severe crash and leads to helmets that are heavy and much stronger than the head they're designed to protect.
- The Snell standard permits a higher maximum force on the head, relative to most other moto tests.
- The force required for a life-altering crash can be generated by the head free-falling from your body height while standing. Helmets don't have to protect against outrageous scenarios.
- I ride a Rockgard'n Blacklite helmet and it's been superb. It's cheap, light (for a moto helmet), and offers more frontal-impact stability than most moto helmets, which is vastly more than any DH helmet. DH helmets feel like toys after riding moto helmets.
- The weight of a moto helmet doesn't bother my pencil neck.
- The Kali Aatma looks like an interesting product. Have a look at: http://www.kaliprotectives.com/moto/
It's true that many D2 riders are fast, but there are large portions of D2 riders who are slow posers or infrequent riders who spend all their time earning money, rather than riding, and like to ride posh gear when they can spare a little time to ride.
I know roughly equal numbers of each D2 rider variety and I know several rippers who use moto helmets.
27% faster in fact. It's been scientastically proven.
Must be because I've protected my head with a proper helmet.
You can order TLD stickers. 
Curious how's the fit of the D3's to the D2's? Is it the same fit comparison?
i heard that the D3 is a little tight around the superior rim of the external
auditory meatus.
Naaah i am joking
i have been reading ASTM F1446: Standard Test Methods for Equipment and Procedures Used in Evaluating the Performance Characteristics of Protective Headgear, and i am just a fan of the terminology.
auditory meatus.
Naaah i am joking
i have been reading ASTM F1446: Standard Test Methods for Equipment and Procedures Used in Evaluating the Performance Characteristics of Protective Headgear, and i am just a fan of the terminology.
Oh btw, I got your emails. Thanks a ton!
And slap a Troy Lee visor on it and post pics of the fit. Do it right.
Lots of online deals on the TLD D2 right now. I just got a carbon (labeled as a Smith) for $170. Google shopping brings up composite models staring at $150.
