The Myth of the Bicycle Helmet

by Mark Stewart on June 14, 2012

For every complex problem there is an answer that is clear, simple, and wrong.

H. L. Mencken

“Be careful!”  “Walk gently!”  “Try not to get hurt!”

Don’t worry; I am talking to myself, not to you.  I am warning myself before I take the leap into a realm of challenging a truism.  In a recent survey, 92% of respondents reported that they are in favor of mandatory bicycle helmet laws for children, and 83% are in favor of helmet laws for all cyclists.  Groups as disparate as the American Pediatric Association and various State Departments of Transportation recommend the usage of helmets for cyclists.  And, on and on.  Yet, they might all be wrong.  Bicycle helmets might not protect cyclists much at all.  And, in fact, in some cases, they might actually be more dangerous than going lidless.

 Horror of horrors!  How dare I suggest such things?  But, please dear reader, please keep reading.  I haven’t even been able to make my arguments or offer my evidence.

Credit: Ildar Sagdejev (used under cc license)

To begin, I would just like to point out some of the ridiculous nature of the whole concept.  I doubt that this avenue of argument will convince many, but I hope you will at least think about it before continuing on to the more statistically focused ones.  The idea that a 4000 pound steel box moving at 35 miles per hour would have limited effect against a plastic and Styrofoam bowl, that weighs less than a pound, is an ignorant one, at best.  (Or, one that delights in sci-fi physics.)  And yet, many people seem to have the idea that if you are a cyclist who wears a helmet, you are safe.  (At this point, please reread the H. L. Mencken quote at the beginning of this piece.)  Let’s look at the evidence, shall we.

In a 2001 New York Times article, Julian Barnes noted that while rates of cycling had decreased between 1991 and 2001, head injuries had increased even though the use of helmets had skyrocketed throughout the 1990s.  The risk of injury per cyclist had gone up by 51%.  Several causes were postulated: antilock brakes, the risk-taking behavior that people do when wearing safety gear, etc.  I hope that you will take a moment to read the article.  Some of the quotes are precious.  “We don’t know what’s going on,” said one political appointee who should know.  Well, I’ll offer my idea.  People accepted the idea that helmets work, and then created studies to “prove” that they do.  But, let’s keep going.

For my evidence on these matters, I could use many sources, but I will focus on the work of W. J. Curnow, who is a leading researcher in the field.  He states that the most common form of testing done on helmets is of the linear impact variety.  That is, imagine putting on a helmet, running at a wall, and measuring the decrease in impact.  Modern bicycle helmets generally perform well at these tests, as they are designed to pass them.  Curnow points out that these tests generally max out at 12.5 mph.  This means, that up to this speed, in a linear impact situation, the helmet should have some increase in protection for the wearer.  His own evidence backs this up.  However, many accidents involving cyclists do not fall into this highly specific category.

Most healthy cyclists, especially adults, regularly cycle faster than 12.5 mph.  And, of course, cars go a lot faster than this, even in school zones.  Also, Curnow points out that the most dangerous type of injury to the heads of cyclists are of the “rotational” or “torsional” variety.  This takes place when the head and neck twist rapidly.  These injuries can cause the brain to become detached from the connective tissue and the brain stem can be torn.  It is these injuries that bicycle helmets make worse, and make happen when they normally wouldn’t.  The thickness of the helmet causes the head to come into contact with surfaces that it would not in a person not wearing a helmet.  Because of this, and the movement and sliding of a crashing cyclist, the helmet will “grab” the ground and cause the head to twist, leading to these extremely dangerous injuries to the brain.

And yet, before studies like Curnow’s were done, there was a push to install helmet laws.  The idea was that helmets work and therefore people should be wearing them.  However, now that time has passed we can see the results.  In a 2012 article from Australia’s Institute of Public Affairs, Australia’s mandatory helmet law (MHL) was deemed a “disaster.”  Australia is one of only two countries to have a nationwide MHL (note: several US States have MHLs).  A few highlights from the article:

“When the laws were introduced in the early 1990s, cycling trips declined by 30-40 per cent overall, and up to 80 per cent in some demographic groups, such as secondary school-aged females.”

“Cycling is generally a safe activity, the health benefits outweighing the risks from traffic accidents by a large margin. British research suggests life years gained through cycling outweigh years lost in cycling fatalities by a factor of 20:1. A recent study of users of Barcelona’s public bike hire scheme puts this ratio at 77:1.”

“By any measure, health problems associated with a lack of exercise are a far greater problem than cycling head injuries in Australia. According to the Heart Foundation, lack of physical activity causes 16,000 premature deaths each year, swamping the 40 or so cycling fatalities.”

So, what we have done is create a society that is absolutely certain that helmets work.  However, the requirement to wear helmets has led people to stop cycling.  This has contributed to the obesity problem that industrialized countries are facing.  And, the people who are cycling with helmets are perhaps more at risk than they were before all of this started.  Well done, everyone!

I will suggest what many have before, that if we really want to focus on cycling as a solution to many problems (obesity, pollution, overcrowded road systems, etc.), we need to look to various countries in Europe that have been extremely successful in moving their societies to the bike.  There is much discussion about the cycling in Denmark and the Netherlands, in particular.  (I will link to one review article that covers much of the information.)  They have cycling rates (e.g. 40% of commuters do so by bike) that dwarf the rates even in our “best bicycling cities” (e.g. Portland, Oregon has about 7% of commuters on bikes).  In Copenhagen and Amsterdam, almost no one wears helmets (about 0.1% of cyclists).  And yet, they have cycling injury rates that are fractions of ours.  They have found solutions to the problems.  We should copy them unselfconsciously.  And thank them for the 50 years of trial and error.

At the end, it must be pointed out that cycling has a similar risk of death as being a pedestrian.  Should we all wear helmets when we walk around town?  Cycling is, in fact, more dangerous than being a driver (based on miles travelled and trips taken).  But, it is not as great a difference as you might imagine.  What would Ford, GM, and Toyota say if we started recommending that every car come with built-in helmets for driver and passengers?  What would they think?  How much time, effort, and money would they spend convincing all of us that it is a ridiculous idea?

Works Cited

Pucher J, Buehler R.  Making cycling irresistible: Lessons from the Netherlands, Denmark, and Germany.  Transport Reviews.  July 2008, 28(4), 495-528.

Transporation Accident Analysis and Prevention.  Anton De Smet.  Nova Science Publishers, Inc.  Chapter 6: Bicycle Helmets: A Scientific Evaluation.  WJ Curnow

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