350htrr

I think you have a point there, I too suggest that in real life there would be lots of heads that hit the ground that are just not counted because there was not sufficient injury for the person to go to emergency... Why you may ask? (a)Because the helmet saved the day, (b)the impact just wasn't hard enough to mater so the helmet didn't do anything, (c)The impact wasn't hard enough and it didn't mater that the person wasn't wearing a helmet...

mr_bill

There actually are several great helmet studies that answer the question about low energy crashes with and without helmets - just they involve motorcycles. Two riders on one motorcycle crash - one with and one without a helmet. One ends up in the hospital, one doesn't. (Guess who.)

(For some reason the data set of bicycle tandem riders who crash, one helmeted, one not, is to a first approximation the null set.)


But no matter, there is no study the anti-helmet crowd will accept, unless of course the conclusion matches their bias.

-mr. bill

asmac

Especially when it doesn't support your point-of-view.

The study concludes that bike helmets reduce brain injury by about half and that helmets are, all things considered, a good idea. Sorry you disagree but just don't put yourself up as a facts-based expert when you clearly are not.

It's been a fun expedition into this wacky corner of bf but I think I'll go back to ignoring it (like most people).

Carry on...

D1andonlyDman

BTW, this is a textbook example of selection bias and the incorrect use of an improperly selected biased data set to form an incorrect anecdotal opinion. If you don't know what that means, look it up. As a Paramedic, you saw the people who were injured. You did not see the people who were NOT injured enough to require a paramedic - in many cases BECAUSE they were wearing a helmet,

daihard 

How do you know they weren't injured enough to require a paramedic "in many cases" because they were wearing a helmet? I don't doubt there are cases like that, but there should also be many who weren't injured enough without a helmet.

D1andonlyDman

If they hit their head onto asphalt or concrete, and they weren't wearing a helmet, they most assuredly need to be seen by either a paramedic, or a mortician, and in the case of the mortician, someone needs to declare them dead first.

350htrr

That's the problem... Nobody knows how many that number is (no helmet nothing much happened) (helmet but nothing much would have happened anyways) or (helmet saved some maybe a lot of injuries)... If 10,000 people a year (made up number) bounce their head on pavement and lets just say 1/3 nothing, 1/3 nothing but 1/3 there is some/lots of benefit that's 3,333.3 people helped that aren't being counted because they didn't go to emergency... JMO

EDIT; Again just made up numbers to try and show how it could be, how all those people aren't represented...

daihard 

Most assuredly by who? Chances are, if you hit your head lightly because of a fall, you will not need to be treated with or without a helmet. You may also realize that not all accidents involve head injury. Of the 100 bicycle accidents, only 20 may involve it. Of those 20, only 5 may cause a serious enough head injury. Of the 5, only 1 may be just severe enough that not wearing a helmet would have caused the person to die or sustain a serious brain damage but wearing a helmet would have saved him/her from that.

This goes back to my original post about risk assessment. If you feel you want to wear a helmet for that 1 percent probability, it is your decision and no-one else's. OTOH, if you're willing to take a chance since the probability is low enough for you, again it's your call.

[EDIT] Just realized @350htrr posted something similar above.

wphamilton

That's actually a pretty big reduction in risk when you consider that these are severe injuries. But for the actual risk multiply by the chance that it occurs, which is extremely small there. 150 cyclists in a billion kilometers, not worth the worry

D1andonlyDman

If you don't break your fall, hitting your head on asphalt or concrete, from a height of 5-6 feet above ground driven by nothing but the force of gravity is absolutely 100% guaranteed to not be hitting your head "lightly". If you don't believe me, why don't you try it some time. Frankly, without a helmet, you'd be very fortunate to ONLY sustain a mild to moderate concussion from such a fall. Basically, you're bouncing your head directly off of asphalt or concrete at ~13 MPH. That's the velocity attained strictly due to the force of gravity from a height of 5 feet 7 inches.

daihard 

Your assumption is that you don't break the fall and hit your head on asphalt or concrete. That already takes a lot of probability away because not every fall occurs like that. I've fallen 4 times in the last 12 months. None of them involve hitting my head at all. I had a helmet on, but it wouldn't have mattered.

In case I wasn't clear, I'm not disputing the relative effectiveness of the bike helmet in certain types of accidents. All I'm saying is that it's about risk assessment. If one decides that the convenience of not wearing a helmet outweighs the risk of not wearing it, it is his/her own decision.

D1andonlyDman

I never said that every, or nearly every fall happens like that - but certainly plenty of them do. And for THOSE type of falls, you damn well will be better off if you're wearing a helmet.

Of course a helmet doesn't do anything for you in falls where you don't hit your head at all. Who ever claimed otherwise?

If your argument is that you don't need a helmet because you won't ever hit your head, I say, good luck with that - it will be true until it isn't. And then, you'll be S-O-L.

daihard 

My argument from the beginning is that whether or not to wear a helmet is up to the individual rider according to his/her risk assessment based on his/her own data analysis and experience.

D1andonlyDman

Sure, but keep in mind that having a previous experience of not having hit your head while not having worn a helmet is also an example of extreme selection bias. Many of the folks who HAVE hit their head while riding without a helmet don't get to do that sort of risk assessment - or any data analysis at all.

daihard 

I am well aware of that. I maintain my stance about bicycle helmets - I respect your decision based on your judgment.

wphamilton

You did say "most assuredly" a cyclist would need a paramedic at least. I read it the same way he did.

Is it really "true until it isn't"? We can put some actual numbers to it. People will gripe about the data, but it's better than guessing with no data. The NCBI National Household Travel Surveys has that 1.7% of the population does "any cycling". USDOT statistics show an injury rate of 157 accidents per million population in a year of cycling. So it implies roughly a 1% chance of injury accident in a year, for the cycling popuplation 157/(1,000,000 x .017) = .00923 After 30 years of that risk, the chances of having an injury accident are still only 25%.

Obviously the chances of injury are higher for people who cycle more, so what of that? The survey has 0.9% of the population cycling at least 30 minutes per day, so plug that in instead of the 1.7%. I still get only about a 43% chance of having an injury accident after 30 years.

So based on these numbers, such as they are, I have to say that you're mostly wrong about "it will be true until it isn't. And then, you'll be S-O-L." It will remain true for most people, and they most likely won't be S-O-L.

D1andonlyDman

I'm sorry you read it that way, but it's never too late to take a refresher course in reading comprehension - particularly with respect to understanding context.

Yes. IF one hits their head without breaking their fall, they WILL, GUARANTEED, need a paramedic - or a mortician. I never said that everyone crashes, and I never said that all crashes involve hitting one's head. But, IF you crash, and hit your head on concrete or asphalt without breaking your fall - well, under those specific - very plausible assumptions - there isn't going to be any "lightly" about it, because gravity alone will result in the velocity of the impact of the head to the road being about 13 mph - even assuming zero added momentum from the speed the cyclist was moving. And that speed of impact WILL, no ifs ands or buts, cause injury to the un-helmeted head - if you're LUCKY, that injury would ONLY be a mild to moderate concussion.

And, it is a factually correct statement that everyone is un-injured by accident - until they get injured (and of course, many folks never do). But those that do get into an accident involving hitting their head on concrete or asphalt, while not wearing helmets, are S-O-L. Jeez, you would think folks could read and comprehend a simple paragraph written in the English language.

wphamilton

You added a qualification there, and it's good that you clarified.

If I were to quibble, it would be the emphasis on "breaking their fall". What you mean is if the head falls to the pavement in the manner of an object in free fall, and yes it's surely correct that it would result in serious injury or fatality. A break-fall to me means one of several techniques that one learns by training in any of several disciplines, which implies a more rare skill. But, most people naturally break their fall in some manner even with no training or practice, sometimes even accidentally, so that's a very big "if" that you're emphasizing. The accident numbers bear that out as well, if you look at the ratio of fatalities to general accidents. What you describe is, in reality, a rare occurrence.

D1andonlyDman

And I never excluded the possibility of breaking one's fall. I DO exclude the claim that a rider in a crash will ALWAYS be capable of doing so. If, for example, your arms are pinned, or injured in a collision, or you have been thrown at high velocity, and or are disoriented by the initial impact event, being trained in fall-breaking won't do you any good.

And the fact is, helmets are designed for rare occurrences. They have an expected useful lifetime of ONE crash event. And ideally, that never happens. But if it DOES happen, that's when you really want to be wearing one. And those events are highly unpredictable in nature, even as they are low probability events.

wphamilton

Granted, but how probable is that in reality? It's all about risk assessment, and the probability of the event is at the core of it. The data I've seen suggests that it's improbable to the point of being a trivial risk. I'd be glad to see some information that is more accurate, or suggests that your scenarios are more common.

added: let me just emphasize, the probability of ANY accident is just 1% as shown earlier. Fatal accidents are 670 fatalities among 49,000 injuries. So that's what, .0001 chance of it for a given cyclist in a given year?

oh, and it's off topic, but you don't necessarily need your arms if you're trained. I'm not talking about trained people though - that was basically my quibble about using "break fall", since it implies that only training lessens the impact. Ordinary people with no training will naturally break their falls.

D1andonlyDman

Probable enough that, assuming one's brain is valuable, it's a good idea to protect it. Which brings me back to my initial point: the benefit of wearing a helmet is the probability of it actually fulfilling it's intended function, multiplied by the value of the brain it is protecting. And if one does the cost-benefit analysis - not everyone's brain is valuable enough to get over the threshold of making helmet usage worthwhile. My brain is. I can't speak for others.

It's analogous to having fire insurance on your house. Most folks never use it. But the folks that did use it are glad they had it.

wphamilton

Not exactly. It's the probability of the event occurring, times the effectiveness of the helmet in the event, times the value of the item saved. Actually you'd sum them up for all possible events, but we're simplifying. Leaving out the first probability, your equation is off by four orders of magnitude.

There are many risks that we take routinely, risks of debilitating injury or death, which we simply ignore because the probability of them occurring is so slight.

D1andonlyDman

No, I did not leave out the first probability. Actually, the first term of my equation was the combination of the first two terms of yours - it included the likelihood of the event occurring, and the likelihood of the helmet fulfilling it's function IF the event occurred - simplifying, as it were. I accept that it is a quite small number. But in my personal equation, the value of my brain dominates even a very small first probability. I also accept that not everyone's brain encompasses a high enough value to overcome that first very small probability. Mine does. Roughly speaking, even if the likelihood of MY worn helmet saving my brain is on the order of 1 in 100,000 to 1 in 1 million, per time worn, MY brain is worth enough that that is a very good, very cost effectve risk-mitigation strategy. As I said, many folks brains are not valuable enough to rise above that threshold. Mine is. I'll also contend that my brain clears that threshold with perhaps 2-3 orders of magnitude to spare. Again, I agree that not all brains do clear that threshold.

And I will grant you that foolish people ignore small probability risks that have high consequences routinely. That doesn't make it an intelligent or in any way optimal strategy. Intelligent people still mitigate those risks wherever reasonably possible and cost effective - for example, when driving, they wear seat belts, drive cars with good collision-worthiness, and drive at speeds well within their and their vehicle's capacity to handle, don't drive while impaired, don't use their cell phones while driving, etc. It may be boring, but it's a good way to increase the odds in your favor. Just as wearing a helmet when bicycling does.

daihard 

With a probability of 1 / 100,000, the event would occur once about every 138 years, on the assumption that you ride a bike with a helmet on twice every day. I wouldn't consider it foolish to decide that probability is low enough to justify not wearing a helmet.

D1andonlyDman

Sure, if your brain is not extremely valuable, you could draw that conclusion. As I said, my brain happens to be worth enough that even an extremely small probability of harm coming to it would be highly unfortunate. But one cannot generalize that statement across all brains.