meanwhile

I don't think you understand what I said: I didn't say that the **facts** were untrue (I explicitly said that you did crash and were wearing a helmet) but that your interpretation of them was false.

Ok. What's you don't get that your helmet, according to everyone worth a damn including the helmet makers, did not work correctly according to the evidence you gave. If the shell broke, then the foam didn't provide brain cell protecting deceleration - as you should know if you read this thread. Yes, the helmet probably saved you from some scraping - but at the cost of increasing rotational damage, the real brain cell killer. It's quite possible that you traded off some IQ points for that reduction in tarmac shaving rash.

There's probably nothing you could understand, yes.

That's a common sense thing to think, yes. But it is also wrong - heads and helmets work quite differently; if you'd hit without a helmet at 18mph your neck would have flexed to absorb the impact, not the bone or brain. And no, your neck wouldn't have absorbed more stress without a helmet, because my wearing a helmet in an accident like this you increased the rotational force.

To make this really simple for you: Helmets are virtually always found broken after the type of accident you describe (if they stay on the wearer's head). But helmetless riders heads are not found to be broken like eggshells at any greater frequency than those of the helmeted.

Not that I want to sound like I'm your teacher criticizing you for not reading your assignment - but if you read this thread then, according to expert testimony that is uncontested by anyone worth a damn, you should know that a helmet with a cracked shell did NOT work. What's the cognitive problem that stops you applying this to your own case?

nycwtorres

"Everything you say is wrong." That's all you have to say to me.

nycwtorres

The only real conclusion of this thread is that there is clearly no source of data worth believing on the topic of helmets; the "yays" deny the data of "nays" and vice versa. What is left to believe?

I think it's just a conspiracy, that all those posters on this thread are actually terrorists trying cause physical harm to peace loving civilians of the western world, with the secondary motive of ruining the whole industry of helmet companies. They are forcing a negative campaign on readers resulting in a decline of helmet sales and a # of companies shutting down firing hundreds of employees and thrusting them into poverty. No THERE is something worth believing.

alhedges

This is not even true. I wore a helmet for years, even when I lived in Germany where no one else did. I went out of my way to make sure that my helmet was Snell and ANSI certified. I heard all of the "a helmet saved my life" stories, and I believed them. I believed that bike helmets were 85-88% likely to prevent head injuries.

Then, a few years ago when I was looking for a new helmet and couldn't find a Snell certified helmet, I did some research on helmet construction and found that I buy one that was as protective as the helmets that I wore in the 80's and early 90's. And I learned that a broken helmet was a helmet that failed, not a helmet that protected the wearer (and I have never heard a motorcyclist talk about how his helmet saved him by breaking). And then I found out that the 85-88% statistic was, to be completely accurate, a lie. And then I read the population studies from Australia - the best data there is - and found that bicycle helmets made *no* difference in the rate of death or serious injuries.

And then I read from helmet makers that helmets wouldn't protect you in a collision with a motor vehicle. And I discovered that biking is about as dangerous as walking. And realized that if biking was as dangerous as walking and only protected against the same type of injury that might occur while walking, that I should wear a helmet while walking.

Then I realized that wearing a helmet while walking was stupid...but no more pointless than wearing a helmet while biking, so I stopped wearing a helmet.

And of course I realized that the biking industry - from helmet manufacturers to LBSs - had a huge incentive to push helmets.

Could I be convinced to wear a helmet again? Of course - but I would need some real scientific data - like another population study, only this time showing a decline in deaths or serious injuries after the number of people wearing helmets increased. But some D00d on the internet claiming that helmets saved his life three times or whatever won't convince me.

I stopped wearing a helmet

wink

I do wear a helmet on rides any where except around my neighborhood at 8 mph.When I ride on my longer rides I feel like I am missing something if I don`t wear it.Also I dont mind as it keeps the sun out of my eyes and to me is cooler than with out it.If you go to cheap and get a heavy helmet you most likely will now wear it pay a few bucks for one that fits comfortable and is light with vents for air you mite find you like it.

RazrSkutr

Canadian Broadcasting Corporation radio interview covering the dangers of Mandatory Helmet Laws. Pretty good except that the spokesperson pushes for separate facilities instead of emphasizing that bicycle accident rates are actually really, really low and riding with cars is pretty safe if you behave in a sensible manner.
https://www.cbc.ca/montreal/media/aud...c2_helmets.ram

John C. Ratliff

I have been off this thread for several months to do some writing, but it is convenient that the monitors had to start a new thread to allow people to keep posting. If you'll look at the older thread (it's still there, just buried) you'll see plenty of arguments by people who have some expertise in the subject.

You say that the cracked shell means it did not work; does it mean that the crumple zone in a car does not work if the metal is broken? Does that mean that the water barriers which are impacted by a car did not work if they break? Not hardly! It means that they were tested beyond their compressive ability, but that they did absorb the maximum amount of force that they could absorb before failing. If people are to simply "read this thread" and the poorly thought-out assumptions by those against helmets, then they are not doing their due dilligence in assessing the risk. By promoting this hogwash, Meanwhile, you are saying simply "trust us, we know what we're saying" while you won't even give us your names.

Here are a few of the newer studies on the subject:
https://www.ncbi.nlm.nih.gov/pubmed/1...ubmed_RVDocSum

https://www.ncbi.nlm.nih.gov/pubmed/1...ubmed_RVDocSum

John



John

RazrSkutr

The bicyle helmet equivalent to a car with a smashed up crumple-zone or a burst water barrier is a [bold]crushed[/bold] helmet liner. It's incredible that you would have been such a long-time poster to this thread and still not understood this. A cracked shell is not a crushed shell.

The response is non-linear. (Get someone with a technical background to explain this to you. I don't think you're going to be able to work it out on your own given that you've been around this long and still haven't grasped this point).

Which have apparently no relevance to your assertion that a cracked helmet shell indicates that the helmet "absorb[ed] the maximum amount of force they could absorb before failing". Try to stick to the point instead of confusing things with spurious cut and pastes (unless of course you're hoping to hide behind them.)

John C. Ratliff

RazrStutr,

I'm amazed that you cannot understand some basic physics. Take a look at these:

https://www.grantadesign.com/resource...ies/helmet.htm

I don't think you can comprehend that this is a "closed-cell foam" which can compress upon loading, and when the load is not there, it will return to it's original form unless it fails completely. But you won't be able to see that unless you take the helmet's foam, section it, and put it under a microscope to see the foam cells that have collapsed. It is like a diver's wet suit, which when under pressure of 33 feet of water (2 atm absolute) will compress to about half it's original thickness. When the diver surfaces, the wet suit expands to its original shape, unless it has been crushed by taking it extremely deep.

If you really want to read about this and learn, get the following paper:

Mills, N.J., C. Fitzgerald, A. Gilcrist, and R. Verdejo, "Polymer foams for personal protection: cushions, shoes and helmets," Composite Science and Technology, 63 (2003) 2389-2400. You will have to pay for this paper, but it is available using Science Direct.

You can see some of this in Dr. Mills book, Polymer Foams Handbook, available in an on-line preview.

Now, back to some different writing.

John

RazrSkutr

1. Loading can occur at different speeds. The response of foams is not linear and a crack can indicate that the loading rate threshold was reached.

2. Surely even you would admit that a crack is a complete failure?

Your first link is entirely irrelevant to your statement that a cracked helmet shell indicates that the maximum possible amount of energy has been absorbed.

John C. Ratliff

RazrSkutr,

Of course loading occurs at different speeds. That is the basis of the use of helmets. Take a look at Dr. Mills Figure 14.2, where he traces out the curves of force applied verses time in milliseconds. Note that the force without a helmet peaks at over twice the height of the force curve with a helmet. With the helmet, the impact is spread over a longer time, due to the crushing of the foam. Sure, a crack can mean that the loading threshold was met, but the time is still spread out by the action of the helmet.

For your #2, you assume that if the helmet cracks, it doesn't also compress and crush. I know for a fact that this is not true, as I have examined my own helmet. Although it broke into many pieces, it also crushed, and thus absorbed energy from the fall that otherwise my head would have had to absorb.

This is what I got back from the doctor, in a plastic bag.


Here it is pieced back together to see what it had done, and what it had absorbed. Note the difference in the thickness of the two opposite sides. It takes time to crush foam like that, and those milliseconds added are enough to distribute that force curve over a longer time, and therefore lessen the amount of force per unit time that my head had to absorb.


Even though my helmet failed "catastrophically" it still was crushed, and that cause time to be added to the equation, lowering that curve Dr. Mills shows in his book, and distributing the forces over a greater time. This is how a helmet works, and the fact that my helmet broke apart affected only the second impact, not the first.

By the way, I now wear a helmet with a "molded-in shell" or a hard shell (my summer and winter helmets), which won't prevent the foam from cracking, but will prevent the helmet from coming apart.

Now, the question really is whether you would wish this process to happen at your scalp, which is only some 5-7 mm thick, or at the helmet, which is 20-30 mm thick (plus that 5-7 mm thick scalp)? Without the helmet, there is very little but flesh between the asphalt or concrete and the skull. Take a moment to strike your skull with your fingertips firmly (but not hard). Feel how much "give" you get between that fingertip and the skull bones--it doesn't feel like much to me. I say this because there is another thing happening with the helmet. Not only is the time lengthened, so that the force is dissipated, but also the area affected is greatly increased, so that the force is not applied to as small an area. This further dissipates the forces onto the cyclist's skull. Now, put your helmet on and strike your helmet with your finger tips. Does that feel a bit different?

We use these same principals in the martial arts, but to disable and kill rather than to keep safe. The Karate Knife Hand technique of breaking boards or cement uses the concentration of force on a small area to cause the fracture. It requires a lot of skill and speed to accomplish, but once learned it can be applied to self-defense with devastating results. Likewise, we can use the Judo technique of breaking a fall by applying force over a large unit area, rolling with the fall, or slapping the ground to break the fall. These falling techniques apply the same principal that the helmet uses to dissipate the force of the fall. Now, I'm curious as to whether a karate practicioner can break a board with his or her hand if bicycle helmet material is applied over the top of it. My bet is that (s)he cannot, even if the foam cracks. Anyone care to try?

John

trombone

Hello John!


I'm constantly amazed at the low quality of research published into bike helmets. I'm also somewhat puzzled that you choose to cite so much of it; those two studies you linked, simply from reading the abstracts, are dreadful!

The first one is sort of a meta-study, although a very poor one. (It's worth noting that meta-studies are themselves somewhat controversial; they tend to exhibit publication bias. However, they are cheap and easy to do, so there are lots of them).
The study you cite, though, falls directly into this trap. In fact, it does it with breathtaking overtness:
' Conclusions: upon the literature, the number of studies proving the necessity of helmets is higher than those objecting to them'.
Good heavens. If research has been dumbed down to the extent that simply counting papers is considered acceptable, then we're all in trouble.

The second one is also a good example of how so many of these studies are constructed; this study actually says nothing whatsoever. It's and expression of the blindingly obvious coupled with an untested assertion.
The blinding obvious bit is that cyclists get injured in Hong Kong. Wow. Hold the front page everyone. (This is a subtle example of selection bias. Motorists get injured in Hong Kong. Pedestrians get injured in Hong Kong. Yet the study selects only cyclists).
The assertion is that therefore helmets are needed. You may or may not agree with that point, but the study does nothing to address this point. I daresay it cites some other research (a further example of selection bias), but it actually adds nothing to the debate on this issue.
So overall, it's fair to say this research adds nothing to the debate about cycle helmets; at best it simply sheds some light on the type of injuries received by Hong Kong cyclists. Sort of interesting, I suppose, but not relevant to the helmet question.

meanwhile

Complete with an itemized list of your beliefs with objective wells-sourced
reasons for said wrongness, yes. For feck's sake - the helmet manufacturers and guys who give evidence in court cases say that you're wrong!

I'll also point out that you're somewhat hypocritical to object my telling you, with reasons, why you are wrong - when all you do is the same, with much less competent research.

meanwhile

I would if you had ***supplied a link***.

John, once again your reading skills and grasp of facts appall me: this isn't an "assumption": it's expert testimony. Go and read the wikipedia page on helmets and follow the link.

No, John: you don't "know this for a fact". What have you did was you eyeballed something and saw what you expected. You thought - without using a measuring tool - that you saw some compression and that was good enough for you. You didn't bother to find out how much compression and where you would have to see it for the helmet to have had the effect it was supposed to, because what you saw agreed with you. Anything that didn't, of course, you threw out.

Frankly, that you think your claims constitute sufficient evidence to throw out lab results repeated for decades and accepted even by the helmet makers just shows that you're not a person who lets facts get in his way much.

Everything in the universe takes time, John - even bad physics. While the above is true, it's overly simplistic and doesn't take into account basic real world stuff. Eg at the point foam stops compressing it will have become (doh!) incompressible... what happens to the helmet and the brain inside then, if there is still velocity to be shed is something that you haven't thought of.

Another thing you haven't thought of what is what happens to a helmet that breaks at the liner. My expectation is that (doh!) it would be trapped momentarily between the wearer and the ground, causing rotational damage. The foam at the contact points will compress, but the greater mass of foam that would share the impact energy in a "good" helmet hit won't. This is what you saw, but didn't understand.

Says who and at what speed? What certification guarantees that at, say, the 40mph of a typical post car bonnet encounter? How much does the helmet weigh? Seriously, if what you have claimed isn't nonsense, I'm interested. High risk riders like messengers could benefit from a helmet like that.

Ok: the debate just got stupider. Board breaking is a dojo trick for impressing idiots and while there are idiots who believe all sorts of idiocy about break falls, in the real world (which isn't covered in thick squoshy mats) they don't work so good. Neither technique is relevant to the substantive issues, which are whether a helmet provides deceleration in a serious accident, whether this compensates for the extra risk of rotational injury, and whether the risk of serious head injury is great enough to occasion wearing a helmet to begin with.

meanwhile

No, it isn't incredible at all. Somewhere on the Internet there is some, umm, "person", capable of any degree of cognitive malfunction.


That's pretty much it, together with -

- Population studies show much the same rate of serious head injuries for the faithfully helmeted and the nakedly disobedient

- The stats for the UK say that each cycling death represents 3000 years of cycling. I'd worry more about saddle sores if I was going to be on a bike for that long - after the first decade of continual riding I'd probably be looking for a semi to bring a nice quick end to my suffering.

TechKnowGN

So, I dont have the time, effort or inclination to read all 13 pages of this thread.

I have a couple simple questions.

1. Does the science prove I will hurt myself worse by wearing a helmet?

2. If not, then why should I not wear a helmet, even if the basis for it providing protection is mostly anecdotal?

chipcom 

Nobody cares (or should care) if you wear a helmet or not. Right?

RazrSkutr

No one knows one way or the other. It may mitigate low-speed, simple falls. On the other hand it may exacerbate the injuries from falls with a rotational component. Helmets made of harder, less-compressible foam would be better for higher speed falls and worse for lower-speed falls and vice versa. It's impossible to give an answer one way or the other.

Because they seem to put people off cycling (for a variety of reasons including fear -- if you have to wear protective equipment and it's a minority activity then most people are going to shy away from it). That's individually bad for the people that are not getting exercise and bad for the group of cyclists (helmeted or not) who benefit from the effect of motorist familiarity with cyclists the more there are of us.

If you feel happier with one you should wear it regardless of the above reasons: it's your head, it's your choice and no one has the clear certainty to tell you what to do with it one way or the other. Have a good ride!

RazrSkutr

To me that's the clincher in this debate. After nearly two decades of testing of this safety device on the populations of entire countries I'd expect to see some clear effect if it was any use.

John C. Ratliff

Meanwhile,

Here is the link:

The Polymer Foams Handbook.

This link was in a post above, but I guess your reading skills and observational skills for links are worse than mine. I must have hit a nerve in order for you to engage in such personal attacks.

John

John C. Ratliff

Meanwhile,

You quote Wikipedia as if it is a definitive source. It is not. The quote you say states that helmets with cracks are not effective is shown below:
Now, it is that second statement that you asked me to follow up on. I did, and have looked over the study it came from. But more importantly, that statement's context is not the same as is in the paper. Here is how the statement inthe paper reads:

Do you see a difference in these statements that I have underlined in the study by Morgan and Scazo in their paper "Improved Shock Absorbing Liner for Helmets"? What they actually said is that once the cracks occur, further ability to absorb shock is compromised. But tables (which I'll copy and post when I get home) in the appendices of this paper show conclusively that even with severe cracks, many of the foams (with one exception) compress and absorb a lot of shock.

As I stated above, the Wikipedia site may have a lot of good information, but it also needs to be looked at very closely. In this case, the quote was incomplete and a single sentence which seemed to fit the bias of the authors of the Wikipedia bicycle helmet website. Taken out of context, it seems to say that the foam is not at all effective, when the tables show signifacant crushing even when cracking is severe. The paper's whole point is not that helmets are not effective, but that duel-foam liners would make for better helmets.

John

John C. Ratliff

Here is that table I talked about above:

On one of the foams, the headform "went right through" with "severe cracking." This showed a peak deceleration of only 96 g's. The other foams performed much better. And one duel-foam sample, while showing severe cracking, also had quite good numbers for crushing and comparable numbers for time of deceleration.

John

Basil Moss

Hi John, are you wearing your helmet in the shower, or when out walking your dog yet? If not, let me reming you of the potential, however small, for serious head injury. And suggest that you wear protection, no matter how slim and ambiguous the evidence for it's efficacy in the aforementioned unlikely scenario of your hitting your head on a car, pavement, towel rail, dog doo doo etc...

RazrSkutr

No he doesn't. He points you to the wikipedia as a handy list of references on the topic. Apparently you had no trouble deducing which specific reference he was quoting.


You were arguing that cracking indicated that a helmet liner had absorbed the maximum possible amount of energy. Nothing in the tedious exchange which has followed from that surprising statement supports your assertion. Again, stick to the point and please don't go home and copy and paste a bunch of irrelevant crap in an attempt to deflect from your serious misapprehension on how helmets work.

meanwhile

Possibly because of his own crash, torres can't remember - or perhaps can't understand - the answers he has already had to these points:
[*]Cherrypicking different cities and years can prove helmets decrease, have no effect on, or increase danger
[*]US stats on helmets worn at fatal accidents under report helmet use[*]Stats that actually have a large enough sample to matter a damn show no significant advantage to helmet use
[*]The stats reported for NYC do not matter more than the world just because he lives there - really!

This will risk overloading Torres with data, but he might have have tried reading the rest of the report. If he had, he'd have seen that 92% had committed suicide by bicycle - they wre RLJers, wrong-way riders, etc. To point out the obvious (except to Torres)

1. The sort of people who choose to wear a helmet are... wait for it... safety conscious. They're much less likely to indulge in in quasi-suicidal behaviour

2. If the safety stats say the "distance" between fatal accidents is 3000 years, and this figure goes up to 30,000 years if you don't do anything stupid, then would a helmet be worth wearing even if did protect effectively? Wouldn't carrying a portable lightning conductor or bear repellent be a better investment in safety for the average NY bike rider?

Finally, the completely eliminate any doubt that it is differences in behavior and not the benefits of helmets that are being measured, as the report says, the dead were disportionately male to a LARGE degree. Unless you believe that bosoms protect the "user" from crash damage, this says that the it is behaviour that was being measured: the group of biggest and least competent risk takers were a subset of the helmetless, some of 'em died, boo-hoo.