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Monday
Nov292010

Statistics

37.8 % of all statistics are made up on the spot by the 26.9% of statisticians who are in the ball park when they should be back at the office gathering facts to back up their statistics.

I can vouch for the validity of those figures because I just made them up. Whether or not you find that funny will depend on your falling into the 49.3% of people who are skeptical over statistics.

The thing that makes something funny is when a statement contains a modicum of truth, and the point here is that some of us are skeptical of certain statistics. Whether we buy into them depends on our opinions to begin with.

Here is one I see all the time:

 “Wearing a bike helmet is estimated to reduce head injury risk by 85 percent.”

I’m not sure where this one started, but it has been around for twenty years or more and I’m assuming that originally it had some other statistics and solid data to back up that figure.

It has been repeated over and over, and over again so many times, that it is now stated as fact without reference to the original study. When you analyze the 85% all it does is reinforce a person’s view that bike helmets are a good idea, only if that person held that view to begin with.

Without the original study and the data to back it up, 85% is as meaningless a number as the ones I made up at the start of this piece. Still it is big enough that it sounds good, but not so big that it is still believable if you don't give it too much thought. I think this is what has given this particular statistic its longevity.

I don’t even know anymore if wearing a helmet is supposed to reduce injury by 85% or does it reduce death by 85%? People have accidents with and without helmets, some are injured and some die, but can anyone prove to me that it is even close to 85% survivor and 15% casualty rate.

A few years ago I had a serious accident; I was doing about 25 mph with a strong tail wind, when a person in an SUV turned left in front of me. I was wearing a helmet, but unfortunately went face first into the side of the vehicle.

Maybe if I had the presence of mind to stick my head down, my injuries would have been less, but I was too busy looking for a way around this large object that had suddenly appeared in front of me.

My helmet split at the front, and failed to prevent my eyeglasses from being pushed into my eye, causing permanent eye nerve damage. I also came away with a skull fracture.

So which side of the 85% statistic do I belong? I didn’t die, but I did still end up with a pretty serious injuries. I could join the ranks of those who have a story on how their helmet saved their life. But I won’t, because I am not convinced.

It can be both very difficult to kill someone, and at the same time very easy; it all depends on how and where you are hit. Had I stuck my head down and let the helmet take the full impact, I could have been less seriously injured. On the other hand I may have broken my neck.

I did have some serious abrasions on my scalp that were caused by the inside of the helmet. Never-the-less I was glad I had worn one; for the following reason. Later when my attorney was negotiating a settlement with the insurance company, he was able to say that this cyclist took every precaution to protect himself. He wore a helmet.

I just read an article by an injury lawyer stating that jurors in civil cases have a bias against cyclists. They view cycling on the public highways as a highly dangerous practice, and when people are perceived to engage in dangerous activities, juries tend to place some of the blame on the participant. This has a direct effect on the amount of compensation they award.

By voluntarily wearing a helmet you at least appear to a jury or an insurance adjuster to be someone who takes responsibility for their safety. They cannot award you less with the argument that you didn’t wear a helmet; therefore you contributed to your own injuries.

Unfortunately the 85% helmet statistic gives legislators fuel to press for mandatory helmet use for cyclists. While many more people die each year from a simple trip or slip and fall than from cycling related accidents.

That’s because almost all of us walk on two feet, but only a select few ride a bicycle. Maybe upon waking each morning we should place a helmet on our head before we even put slippers on our feet; not removing it until we return to bed that evening. Viewed in this light does it not make the whole issue somewhat ludicrous?

Making helmets mandatory only re-enforces the general public’s view that cycling is dangerous. I still maintain that wearing a helmet should be a personal choice; making them mandatory stops some from taking up cycling in the first place.

Most start riding a bike without a helmet, a few will become serious and eventually buy a better bike and all the equipment that goes with it, which will probably include a helmet.

To sum up I wear a helmet because it offers some protection; I don’t believe it is even close to 85%, but wearing one can’t hurt. I may hit a pot hole and fall on my head, in which case my helmet may save me from serious injury. But a crash involving a motor vehicle? The best way to avoid injury there is to circumvent the collision altogether.
 

                         

Reader Comments (21)

Every time I'm confronted with the bike helmet debate, this comic springs into my mind: http://www.wulffmorgenthaler.com/striphandler.ashx?stripid=57f6ca71-73a8-42a3-acc4-29e6d333df27

I always wear helmet when I'm riding on the country roads on my road bike. My rationale is that if for some reason I hit the pavement doing 75 km/h down the hill, it just might save my life. I don't have any illusions that it would save me if I get hit by a car.

Helmets are also always mandatory for amateur road races for obvious reasons, when riding in a bunch the risk of having a close encounter with the pavement is quite high, especially if you have a few twitchy, trigger happy inexperienced riders around, braking randomly.

In contrast, I pretty much never wear a helmet when doing errands around the city (Prague, 1.5mil inhabitants, not overly bicycle friendly). In fact, the first time I ever wore a helmet on a bike was about four years ago (I'm 30), and I used to ride a bike pretty much daily since I was a little kid, albeit in a much smaller town of about 35k.

As for the legislation, there was a similar case here last year (I think). A cyclist got hit by a car which did not yield to him turning into main road. He got seriously injured and even though it was deemed it was the driver's fault, the insurance company refused to pay the full sum, based on a premise that the traffic law mandates that while on the road, you should take all precautions to prevent injuries to yourself and other people. Mind you, helmets are only mandatory here for kids under 18 years. I think the case made it to the highest court instance but I don't know how it ended, if it's closed by now at all. If he lost, it would set a pretty bad precedent.

November 29, 2010 | Unregistered Commenters

The 85% figure comes from the 1989 Thompson, Rivera and Thompson case study of child cyclists in Seattle. The figure is still frequently quoted by helmet advocates despite the fact that study's conclusions have been comprehensively discredited by many researchers over the last 20 years. 'Seriously flawed' and 'conclusions untenable' are two researcher's takes on it.
Apart from many other issues, the case study children differed in fundamental ways from the control group used. And as the authors were all pro-helmet advocates that raises serious questions about impartiality.
The whole story is comprehensively covered on many internet sites, it is just sad that the spurious 85% figure has gained a life of its own and is still widely quoted by people who should know better.

November 29, 2010 | Unregistered CommenterAlan Hobbs

s,
Thanks for the link to a great cartoon, and nice to get a perspective from far away Prague.
Alan,
Thanks for filling in the blank on where the 85% originated. I had heard it was from Seattle but wasn’t sure.
Dave

November 29, 2010 | Unregistered CommenterDave Moulton

I clearly remember helmets required a Snell certification sticker to be deemed legal for USCF racing purposes back in the 80s. The Snell test did little to allay my reservations over the effectiveness of the helmets. In the test, a weighted projectile much like a large plumb bob was dropped from a height of six feet. In order for a helmet to pass the test, it had to remain intact while preventing penetration of the object.

The only thing in motion was the test projectile and six feet seemed awfully low. I couldn't imagine that the falling velocity and energy of the object neared the average riding speeds of a fitness minded or racing cyclist. Neither did I believe that the weight of the projectile was commensurate with the mass of a helmet moving towards an object when it was followed by the mass of a human body. I went into the modern age of helmets kicking and screaming because I hated being required to wear one.

In the end, helmets are perceived as safe, pehaps becuase of the 85% statistic. The helmet won't always save a life but I do believe it will lessen the outcome in most instances. Helmets have continued to develop into safer, cooler, and more comfortable headwear from the leather hairnets, to Bell's plastic brain bucket ( that thing was hot and heavy even though it resembled a leather hairnet), to Giro's lycra covered lightweight (the lycra cover required to keep the foam shell intact) to today's lighweight, thin plastic covered shells.

I ultimately changed my view of the despised requirement to one of it well may help and probably won't hurt. I also agree with the view of doing everything possible to be safe and appear safe should the need arise to present yourself as safety oriented. I still however believe that requiring or legislating the use of a helmet is a poor approach to safety. Education is the foundation of safety, not legislation.

November 29, 2010 | Unregistered CommenterJim

The cartoon is so true and the mother epitomizes what cycling advocacy represents in the backwards Midwest USA. Writing laws that require that all cyclists under the age of 18 must wear helmets furthers the "Fear Factor" and fails to address the larger problems (ie. raising speed limits, expanding the number of motorized travel lanes and refusing to enforce speed limits).

November 29, 2010 | Unregistered CommenterJack

Your first line reminds me of Todd Snider's "Statistician's Blues."

November 29, 2010 | Unregistered CommenterMike

Too, helmet laws are sometimes seen as a substitute for poor infrastructure. Who needs to do the hard work of making the sundae when mandating only the cherry is so much easier?

I have found some help in the helmet debate from this quote:

"The safety of walking and bicycles depends almost entirely on the other transportation with which they must mix."

http://www.piercelaw.edu/risk/vol4/winter/halperin.htm

November 29, 2010 | Unregistered CommenterBrent

Dave, You're killing me.

I can't take it anymore. If you get one of these you will reduce your left crosses by 85%. Maybe more..

Yes you will look more geek, but lawyers and juries dig that. I did a survey. I swear, lights during the day have almost eliminated my cross-headaches..

A guy said this light actually works well and he's bought three of them . The blinky works well too. But he might be the guy selling these. Who knows?

If the link doesn't work just do an ebay search for 5W Cree flashlight-torch . the pair should come up at 8.99 , Made by chinese retrogrouches..

Just trying to keep you alive because we all love your cranky-ass blog.

http://cgi.ebay.com/5w-LED-CREE-Flashlight-Torch-Bike-Bicycle-Rear-Light-G-/160430615817?pt=LH_DefaultDomain_0&hash=item255a68ed09#ht_3523wt_814&afsrc=1

November 29, 2010 | Unregistered CommenterRobert Graves

Last year I was out riding my bike WITH a helmet stopped at a rest area on the trail in Parker Colorado, A Harley chap roars infull Harley gear, Leathers chaps etc, NO HELMET! He pulls up next to a Suburau that I assume had his wife in, Opens the back and takes out a super dooper carbon million speed racing type BIKE Changes into his cycling kit, THEN takes out a BIKE HELMET puts this on a rides off down the trail! SOMETHING WRONG with THIS picture, Rides a Harley at who knows what speed NO helmet, BUT rides a bike WITH ONE! This is a true story, Makes one think does it not, Cheers John Crump

November 29, 2010 | Unregistered CommenterJohn Crump

John Crump,
When I worked for Masi in California in the early 1980s, a guy that worked there rode his motorcycle to work without a helmet, but wore a helmet when he rode his bike. It's a fashion thing I guess.
Dave

November 29, 2010 | Unregistered CommenterDave Moulton

Bike helmets work for small crashes and collisions and are going to be largely ineffectual for high speed crashes. (single vehicle or multiple) The 6 foot drop estimates the gravitational force of your head dropping to the pavement. This small drop can cause fairly severe brain damage. Crashing your bike at 35 mph could very well kill you, helmet or not.
I have had two crashes which I don't remember anything except events before and waking up on the ground. I snapped off Look pedals twice and landed on the back of my head. Destroyed both helmets. I'm probably still riding because of the helmets.
Helmets are what they are, protection from falls. They might help you when hit by a speeding car by reducing brain damage. It will depend on how you get hit.

Nice anecdotes about the bikers when they turned cyclist....

November 30, 2010 | Unregistered CommenterRalph

I've been unlucky enough to have had a couple of crashes I think would have been much worse without a helmet on. They're hot, they're ugly, the ruin the carefree image. But once, 20 years ago, I am convinced a helmet saved my life when I was hit head-on by a bus and landed on my head.

All that having been said, when I'm in China for a month or so every couple of years I don't wear one, but their road culture is so much less aggressive than in the west. I guess it comes down to a matter of choice. I reckon adults should be able to make up their own minds on these things. Stuff the nanny state.

November 30, 2010 | Unregistered CommenterSurly Dave

I fell off when a Look pedal snapped too and was glad i was wearing a helmet. Having said that I only started wearing one when it became "fashionable", maybe 10 years ago, For the previous 30 I never wore a helmet, except the hair net variety in road races in England.
I actually don't mind wearing one as they are pretty light these days and soak up the sweat in hot weather so it doesn't run down your face.
But i would certainly not want them to be mandatory.

December 1, 2010 | Unregistered CommenterJohn

I ride now with a helmet after many years of not riding. When I'm at work I have to use one by department decree. I really like the feel of riding w/o a helmet but I've gotten used to wearing one and ride with groups who also require wearing a helmet.

A helmets main function in to reduce the g force load on the brain against the skull in the event of an impact. This should result in reducing the stopping speed of your skull against the object it comes in contact with. The military has helmets for pilots which are built to handle the stress loads. They would be too heavy and impractical for bike riding.

I don't recall the g force shock which can cause brain damage. How ever the amount lowers as we get older. So Dave and I should wear a helmet because we are more likely to sustain damage from a fall than a rider in their 20's.

A side benefit is that it is a good location for a second, or third, blinky tail light.

December 1, 2010 | Unregistered CommenterRalph

Dave, in case you missed this, new article from Bicycling.com. Some good points in it.

http://bicycling.com/blogs/roadrights/2010/11/29/252/?cm_mmc=BicyclingNL-_-2010_12_02-_-blog-_-roadrights

December 2, 2010 | Unregistered CommenterRobert Graves

Helmet has probably saved me a couple of consussions while MTB'ng and doing sudden endos. Thankfully I've only taken a single fall while on the road - a long slide on my right side. Only injuries were road rash and dignity.
Many happy returns to you during this holiday season Dave. Very much enjoy reading your blog.

December 6, 2010 | Unregistered Commenterskylab

A high percentage of people killed in car crashes die of head injuries, perhaps they should be the ones wearing the helmets?

Do bicycle helmets save lives? Possibly. However I would like to see comprehensive real world testing. Test at varying speeds, different types of bikes, different angles of impact, etc, etc. Then they can give us the real percentages.

Aaron

December 8, 2010 | Unregistered Commenter2whls3spds

Yup, that 85% stat is one of the worst that ever was and it never stops being manipulated into something that never was and that's quite something because it never was 85% to start. The authors corrected the figure some years later after it was pointed out to them that the comparison of head injuries against other children who did not wear helmets included injuries that were other than head injuries. No one ever says that. No one also says that 85% figure applied only to children under 5 years old who had simply fallen off their bikes and didn't hit anything on the way down. No one says the same study shows only a 23% reduction in injury for 10 - 14 year olds. 23% reduction doesn't sound as good as 85%. No one also says that not one case in the study involved a collision with a motor vehicle either, just as no one says that the study was funded by the Snell Memorial Foundation with the purpose to show that the recently developed helmet standard was effective. Not to see if it was effective. They hired an author who had already been involved in helmet promotion to construct a result so their standard looked as effective as possible and they could be paid per certification per helmet sold. Yup 85% looks pretty impressive, except it's a myth. A myth perpetrated by those who want to sell a product that costs little to produce and sells like hotcakes for huge profits because easily led people fall prey to their irrational fears and are easily sold an answer that doesn't deliver what they want it to.

December 17, 2010 | Unregistered CommenterBrad

Dave ... I think you're the only helmet wearer I've ever heard of who doesn't claim the thing saved their life or prevented paraplegia at least once. In a blog I was reading just yesterday, a helmet law supporter claimed their life had been saved five times in the last 10 years.

How come people who don't wear helmets (the vast majority of cyclists in the world) aren't all dead or in wheelchairs?

The never-ending "saved my life" claims might make one suspect that wearing a helmet increases risk-taking and thus bike accidents, or increases the risk of head contact because the head area is effectively doubled.

Oh, oh ... that's what opponents of helmet laws have been saying for years.

85%? Based on a discredited study in the voluntary helmet jurisdiction of Seattle 20 years ago?

Want to know the real head injury reduction in a jurisdiction where an all-age mandatory bike helmet law has been in place for almost 20 years?

Mandatory Bicycle Helmet Law in Western Australia

There's a lot of data on this site so If you don't like facts getting in the way of your opinion, or if you prefer TV to the written word, don't bother. Ditto if you always wear a helmet and your cognitive skills have been damaged by constantly bashing your (helmeted) head against the bitumen.

P.S. to abbreviate the results, about a 10% reduction in the proportion (not number) of head injuries. The hospital admission rate per cyclist on the road increased by about 30% (see above), mostly because upper body injuries soared after law enforcement.

December 18, 2010 | Unregistered CommenterChris Gillham

Anyone wanting to examine the results of getting millions of Americans to wear bike helmets? Read http://www.cyclehelmets.org/1028.html

The short answer is: Head injuries per cyclist rose. They rose a LOT.

Despite the "my helmet saved me" claims, these thing just don't work. And the brain injury rate of biking is no worse than for walking. They don't work, they aren't needed, period.

December 21, 2010 | Unregistered CommenterData student

so bit late on this post, but I would say that the issues around wearing helmets can get pretty complicated. For example you could argue that you expect head injuries to go up if more people wear helmets as people who would of died survive, you could also argue that the injuries sustained are less severe (this is what actually happened in 1915 when the British army added metal helmets to the uniform of its troops; cycling on the road however, is not a war zone so the comparison could be limited).

Wearing a helmet does mean that you probably won't end up with daft injuries caused by falling over at low speed and hitting a curb, but unlike what lots of non-cyclists think it is not making you all that much safer nor is it stupid not to wear one! but the opposite is also untrue (spouted by helmet haters) you do not ride more dangerously when you have one on, importantly as well in the urban cycling environment your safety relies quite a bit on others. I do wear a helmet (even though I love riding without one) as I have gotten used to it from more dangerous sports, I have hit tarmac at 25-30+ mph it is not fun. I don't think however this give me the right to shout at others for not doing so (as some people do though not on this blog)

I would also add I think the debate is now moving on (in the UK) which is: if you aren't head to toe in yellow and have 6 lights on then if you get hit it's your fault and you should not be riding... possibly scary times ahead if you are hit.

December 25, 2012 | Unregistered CommenterMartin

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