In response to readers' requests, we have established a helmet FAQ to address some of the difficult questions asked by cyclists who are often confused by conflicting information they get about helmet use and its effectiveness. Our answers are frank and accurate. Unlike many answers on FAQ sites, ours are based on reliable international research and other sources. Where possible we've provided links to source material. [Note, we do not attempt to answer consumer-type questions such as comparison of different brands or how to fit a helmet. These questions seem to be adequately addressed by other sites. Also for the purpose of this FAQ, in our terminology, "cycling" excludes extreme forms of bicycle use like downhill mountain bike racing, where increased risk is the cost of greater performance.]

We oppose bicycle helmet laws of any kind because of the damage done in jurisdictions which have them. We do not advocate the use of helmets, but neither do we counsel against their use. It is clear from the evidence we present that cycling is not so dangerous an activity that their use is particularly justified. We wear no special protective headgear for other every day activities such as walking and driving a car, even though our heads are exposed to similar risks for far greater lengths of time.

We have reason to believe the helmet debate has little to do with safety, and much more to do with commercial interest and a specific lifestyle advocacy similar to that which would control what we eat, drink and take into our lungs. If the debate was about reducing the already low frequency of cyclist head injuries, then the principal issue would be about whether manufacturing standards should be modified in order to ensure production of helmets which actually provided a reasonable amount of protection. Really effective helmets would be of such a design (i.e. ugly) and construction that few would buy them. Also, there are downsides to helmet use and scientific reasons to believe they exacerbate injuries in certain types of impacts. At the moment, a discussion on helmet problems is not in the interests of helmet manufacturers.

If the dicussion were about bicycle safety then we would be discussing how we can get the cycling public to adopt the most effective and proven method of preventing injuries i.e. responsible behaviour and application of skills when cycling. Cyclist education addresses over 90% of all cycling accidents. To put this in perspective, severe head injuries represent less than 2% of all cycling injuries.

Unfortunately, North America's focus on helmets has become so obsessive that the already false notion that cycling is dangerous has been strongly reinforced. It's not surprising that legislators find ready public acceptance of arbitrary laws which restrict bicycle use on our public roads and highways. The result is less cycling than otherwise there would be, and fewer choices for exercise and responsible modes of travel. In this environment, everyone loses.

This FAQ attempts to cut through current bicycle helmet hyperbole to provide the facts upon which responsible people can make measured decisions for themselves.

1. Are bicycle helmets designed to save lives?

If only they were. Helmets which could provide significant protection (if they existed) would be of such construction that few would care to wear them. Modern bicycle helmets are designed to mitigate the effect of an impact to the head of a person falling off a bicycle. At best, they reduce the chance of minor injuries.

"... it is impossible to build a helmet that will offer significant impact protection"

Dr. George Shively, The Snell Memorial Foundation

"... helmets will mitigate the effects of falling off your bicycle and striking your head... If a cyclist is accelerated by a car, then the helmet will not work and will not prevent a severe or even fatal injury"

Dr. Michael Schwartz, neurosurgeon and member of Canadian Standards Association Committee establishing helmet standards

2. Does helmet use save lives or reduce the number of serious head injuries?

Claims of reduction are very suspect. Such claims surfaced in Australia after introduction of helmet laws in the early 1990's. It was subsequently discovered that large reductions in cycling had been ignored.

While US helmet use was increasing from near zero to 30% or more from 1986 to 1996, there was virtually no difference between the trend lines for cycling and pedestrian fatalities. It is difficult to pick out on Tom Kunich's trends chart which line represents cyclists and which one pedestrians. (Data from the US National Highway Transportation Safety Administration (NHTSA)). The results have been the same in Canada where large increases in helmet use have had no detectable affect on Canadian fatality trends.

The rapid increase in helmet use in Australia following legislation showed no helmet benefit. {9} The rates of decline in cycling equaled or exceeded rates of decline of cyclist head injuries. {10} Likewise, New Zealand experienced a dramatic rise in voluntary use prior to mandating but no reduction in the rate of serious head injuries. Reductions in cycling also were experienced. {10}

3. What about the stories of a helmet saving someones life?

We've heard these anecdotes, but the stories you won't hear are the more frequent ones of bareheaded cyclists falling off their bikes without incurring head injuries. They don't lend themselves well to story-telling.

The "helmet-saved-my-life" stories are mostly hyperbole. A plausible explanation for them is that a helmet is a fragile piece of styrofoam which is larger than the head it is on. A helmet on the head of a cyclist who falls from a bicycle on to a hard surface is almost certain to come into contact with the surface and be damaged. A cracked helmet is not proof of protection but rather of a failed helmet{8a}. It's all too easy then to assume a serious head injury would have been incurred without the helmet. Physicians are often the source of these stories, but they have no particular competence in the mechanics of a bicycle accident. When a helmet gets trashed it may well have prevented a nasty bump or even saved a few stitches, but the odds it saved a life are about the same as winning the jackpot in a lottery.

4. What kind of protection does a helmet provide?

Helmets are tested in the lab for straight line (linear) blows only. Test procedures set by standards bodies like Snell, ANSI, and CPSC require a helmet containing a 5kg (11lbs) rigid headform to be dropped onto a flat anvil from a height of 1.5 to 2.0 metres (5ft to 6ft 8in). If more than 300g's is imparted to the headform the helmet cannot be certified.

The outer shell of the 1980's hard shell helmet is designed to spread the force of an impact over a greater area of the head. The micro-shell of modern helmets does not do this, deforming instead and allowing the liner to start compressing at the point of impact. Whether this is good or not is open to question.

All shelled helmets reduce friction in a slide compared to no-shell helmets. The helmet's liner is made of foam sufficiently stiff that the head inevitably will absorb some of the impact. The stiffer the liner, the more shock the head will absorb. Theoretically, the liner is supposed to limit the deceleration for a typical fall on to a flat hard surface to a sub-lethal level, ie. less 300g's, by absorbing energy. Sub-lethal means anything from a very bad concussion to a coma. If a blow is of such severity that the liner is crushed to its minimum thickness, excess energy is absorbed by the head and the blow is likely to be lethal.

The medical profession now believes that even lesser accelerations can produce serious injury and that the 300g level is too high. However, it is unlikely that helmet standards will be raised to provide significant protection because the industry doesn't believe that consumers would buy the resulting products. The trend is in the opposite direction. In Australia, the standard was actually lowered because helmets produced under the old standard did not meet with market acceptance. Manufacturers are presently responding to market demand for helmets which improve air-flow inside the helmet and to fashion by manufacturing helmets with more holes them. While these pass standard tests, they spread impacts over a smaller area of the head, so when an impact occurs it will be more concentrated around the center of the impact.

5. Do industry tests accurately simulate real life cycling accidents?

Yes and no. While the biomechanics of what happens to a cyclist in an accident is very complex, industry tests are extremely rudimentary. The primary objective of head protection is the minimisation of brain tissue distortion on impact. {7a} Tests attempt to replicate a fall from a bicycle where a helmeted head directly hits a fixed solid object. Because the use of a rigid headform is prescribed and the headform's only resemblance to a human head is its shape, test procedures are unable to simulate the effect on a head's bone and soft tissue. In the test, the foam liner being less dense than the headform starts to crush on impact. The test therefore favours stiffer padding. In a real crash, a head and its brain will distort and absorb energy causing cranium distress. An attempt to refute this assertion has been made {8} using a modified head form simulating scalp and hair, but the test has the same limitation of an industry test in that it did did not address the issue of measuring the resulting forces in the brain and the deformation of brain tissue. A report prepared by the Australian Transport Safety Bureau states that research on foam liners from fatal accidents showed little or no evidence of impact damage and that some research reported that the human skull distorted rather than the hard stiff foam liner, resulting in brain damage or death.{8a}

Industry tests exclude any possibility of measuring what might happen inside the skull where brain tissue contorts, rotates and tears as the skull is impacted. The result is helmets being manufactured which optimize padding stiffness even though softer padding could provide better overall protection. The rigid headform is capable of crushing hard-stiff foam liners in helmets, and manufacturers have had to provide high-density liners to pass the impact attenuation and penetration tests. In collisions, the human head is incapable of bending or compressing the foam and the unyielding characteristics of the headform is quite inappropriate as a simulation of the human head{8a}. Reflecting concern over this and the effectiveness of existing helmets, the Canadian Standards Association has altered its test specifications for children's helmets to ensure they are constructed of softer padding.

6. Are helmets supposed to provide protection against all impacts?

No. Sharp, high speed objects are likely to penetrate helmets particularly those with many vent openings. Also, helmet tests monitor the effect of linear force but not rotational force. A blow which is not square on centre, i.e. not linear, will rotate the head. Diffuse injuries - the most serious and common type of brain injuries - result from rotational stresses on the brain. Linear force on the other hand, result in focal or localized injuries rather than diffuse injuries.

It has not been ruled out that the added mass, size and surface texture of a helmet may make the rotational effect more severe. A "safety" device which has been shown undeniably to assist in rotation and increase the risk of diffuse brain injury is the headrest on car seats in rear-end crashes. Nothing has been shown one way or another though, for bicycle helmets. When acquiring new helmets, buyers should consider helmets which are spherical in shape as they are more likely to minimize rotational effect than the trendy duck-shape aerodynamic helmets.

7. How about testing for high speed impacts?

The maximum 2 metre (6'8") drop simulates a 20 km/h (14 mph) impact. Direct impacts over 20km/h can be expected to be lethal.

"One has to agree that in high speed impacts [a helmet] won't prevent death."

Dr. William Lucas, Toronto Coroner, September 1998

8. None of us wear helmets while walking or riding in cars*. Is there any good reason to wear them on bicycles?

Yes, if it makes people feel better, they should wear them. But they should not think of them as a panacea or a substitute for the application of responsible riding habits. Many folks have unreasonable expectations that their heads will be protected by helmets in a high speed crashes with cars.

Many of the same people wear their helmets because they perceive there is a high risk of incurring a head injury while cycling. Skills among cyclists vary, so on an individual basis, some cyclists are at greater risk than others, but unless such individuals are deliberately reckless, their risk of incurring head injuries is extremely low.

Compare cycling with similar activities. Most people don't overly worry about car use and walking* even though they may expose individuals to greater risks. For example, half of America's 40,000 motor vehicle deaths are from head injury. According to the US Center for Disease Control and Prevention,over 30% of all 50,000 US traumatic brain injury fatalities annually result from car use. Yet, less than 1% result from bicycle use. The pedestrian figure is about 7%. Australian figures {10} show that fatality rates attributable to head injury (based on time exposed) are approximately the same for cyclists and users of motor vehicles. The pedestrian rate is almost twice that of cyclists. Despite these facts, the average person fears bicycle use far more than walking or riding in a car. This difference in perception derives from over zealous promotion of bicycle helmets where, in order to get cyclists to wear them, it's necessary to exploit the fears of cyclists by making cycling appear dangerous. The end result is that the general public gets the wrong message about bicycling and believe that helmets are a necessity.

* [Although the obsession over use of helmets has now spread to walking ( in Japan) and
riding in cars (in Australia)]

9. Crash helmets are associated with dangerous activities. Is cycling dangerous?

No, not for cyclists who operate their bicycles sensibly and abide by the basic vehicular rules of the road. That's not to say there are no risks. Some extreme forms of bicycle use such as downhill mountain bike racing appear to involve increased risk-taking. It is appropriate to wear specialized equipment for these, but they should not be confused with utility and leisure uses of bicycles. Any activity involves risk. Climbing the stairs and walking could be considered risky activities based on fatal accident statistics. Each of these activities account for more premature deaths than cycling. Cyclists in North America, even with their low average skill level and often irresponsible behaviour, suffer a lower fatality rate (measured in time exposed), than those participating in other common activities such as car use, swimming and water skiing. {11} Hospitals report no particular epidemic of head injuries among cyclists. Life insurance companies don't increase premiums for bareheaded cyclists. They are more likely to offer a discount to cyclists because of the health benefits derived from cycling.

Car use may be the most dangerous of all activities in terms of accidental deaths, and two articles - one from New Zealand and one from Australia - suggest that the widespread use of helmets (as in car racing) could reduce the number of these deaths. However, it's highly improbable that motorists will perceive their risk great enough to induce them to wear helmets. (Car helmets have recently become available in Australia.)

10. Does helmet use encourage cyclists to behave more recklessly?

No doubt for some it does, although such changes may not result from any conscious action by cyclists. Studies of the effect on behaviour of other safety equipment {1},{13} show strong correlations between use of safety equipment and increased risk taking. This is the "risk compensation" effect. It has been associated with the use of anti-lock braking systems, car seat belts, automobile air bags, ice hockey helmets, and football helmets. Many mountain bikers admit that they would never subject themselves to the hazards of some trails if they weren't wearing helmets. Other cyclists have said they enjoy cycling bareheaded but won't expose themselves to [what they perceive as] higher levels of risk on busy arterial roads unless they are wearing helmets.

Both the latter examples imply that some cyclists change their behaviour with helmet use.

11. What if my children refuse to ride their bicycles when forced to wear a helmet? Is "no helmet, no cycling" a good rule?

Not from a health point of view.

Scrapes, bruises and other minor injuries from physical activities like cycling are a normal part of growing up. Parents of the current generation grew up cycling without helmets. There was no problem then, so why is there a problem now? Children are already less healthy than the children of the previous generation. Child obesity has risen rapidly in the last twenty years partly because of poor diet but also because kids exercise less.

"The gain of 'life years' through improved fitness among regular cyclists, and thus their increased longevity exceeds the loss of 'life years' in cycle fatalities (British Medical Association, 1992). An analysis based on the life expectancy of each cyclist killed in road accidents using actuarial data, and the increased longevity of those engaging in exercise regimes several times a week compared with those leading relatively sedentary lives, has shown that, even in the current cycle hostile environment, the benefits in terms of life years gained, outweigh life years lost in cycling fatalities by a factor of around 20 to 1." {3},{7b}

Mayer Hillman, Senior Fellow Emeritus, Policy Studies Institute, and British Medical Association researcher.

Is it wise to place the benefits of cycling at risk because of misguided attempts to protect children from every possible mishap? As long as your children receive proper safe riding instructions they are probably at less risk of serious injury than they are when taking a ride in the family car (accessed 2008). It's important that parents don't unintentionally discourage their kids from participating in a safe, convenient, and healthy activity.

12. Is promoting the voluntary use of helmets OK?

Constant promotion of helmets diverts attention from effective accident reduction measures and makes cycling look so dangerous that it scares some people off cycling completely. {8} Head injuries result from a tiny portion of cycling accidents. A search of the Internet will show that far too frequently "bike safety" messages focus exclusively on helmet use. Nine times out of ten, the genuinely effective measures of acquisition of skills and rider behaviour get little or no attention at all, yet the skill level of average North American cyclists needs to be radically raised. Bicycle transportation engineer, John Forester {7} shows data which indicate competent cyclists reduce their chances of being involved in an accident by 80% when compared to unskilled cyclists. 1995 surveys in the cities of Ottawa and Toronto, Ontario found that the least competent cyclists - sidewalk cyclists - were more likely than on-road cyclists to wear helmets but less likely to execute left turns from the left turn lane. It appears they have been convinced to wear helmets but not to operate bicycles safely {2}.

13. How should we interpret clinical studies which claim 85% reduction in the risk of a head injury?

With great skepticism. The widely publicized 1987 study of cyclists with mostly minor head injuries received at emergency rooms in five Seattle area hospitals {11} has been roundly criticized for its flawed methodology {9}. For example, the helmet use rate of the population control group of kids under 15 gathered from members of a Group Health Co-operative, was 21.1%, but observed rates of helmet use among kids on the streets was 3.2% {4} as Frederick Rivara, one of the authors of the 85% claim, knew full well as he particpated in the street survey. This suggests the control group was not representative of typical cyclists. The case group of head injured children had a helmet usage rate of 2.1% (3 of 143). This, as a statistician would know, was well within sampling error of the observed helmet wearing rate of the kids seen on the street and therefore suggests no benefit from helmet use. Helmet use among injured kids was actually higher than that on the street (4% vs. 3%) indicating helmeted kids were showing up more frequently at hospitals than the general cycling population. If we used these comparisons and the methods used by the authors, we could say that among children, helmet use increases the risk of an injury by 33%!

The authors themselves admitted in the report,

"We cannot completely rule out the possibility that more cautious cyclists may have chosen to wear helmets and also had less severe accidents."

Indeed, the first of those conditions is more than a possibility. There is evidence which shows it to be the case. In an Arizona study {5}, Farris, Spaite et al found that voluntary helmet users were 2.6 times more likely to stop at stop signs and 7.1 times more likely to use legal hand signals {8}. It's logical to assume then that more cautious cyclists will have less severe injuries. The report concludes that the very strong association of helmet use with safer riding habits has implications for injury-control efforts aimed at preventing bicycle-related injuries. In contrast, the authors of the Seattle study, who are prominent in campaigns to mandate bicycle helmets, have been notoriously indifferent to injury reduction programs which are based on raising the level of cyclists' skills.

There are other biases in the Seattle sample also. We note from the report's data that helmeted patients were from higher income groups. These may well have been more likely than low income earners to show up at the hospital emergency rooms when suffering trivial or no injuries at all. See other criticisms of the report.

Shedding further doubt on the credibility of such studies is that, not only has the 85% risk reduction figure not been replicated among populations which have experienced rapid increases in helmet use, but studies of these populations have detected NO REDUCTION in the rate of head injury that can be attributed to helmet use. {9},{11}

14. What effect has mandatory helmet legislation had?

The principal effect has been to discourage cycling by reducing the amount of cycling rather than to reduce the rate of head injuries. Following the introduction of helmet laws in Australia, the reduction in cycling was actually greater than the increase in helmet use {10}.

A 1997 analysis of US National Highway Transportation Safety Administration data (to 1995) uncovered no statistically significant drop in cyclist fatalities in the eight states which have implemented MHL for at least one year. In the affected age group, New Jersey's fatalities dropped from four to one in the year following the law, then rose back to five the next year! California's changed from an average of 34.75 fatalities in the four years before the law to 34.5 in the two years since the law. Significant drops in children cycling to school have been reported after the introduction of the helmet laws. When cyclists quit cycling and turn to sedentary lifestyles, the general health of populations decline. Everyone among those populations pays the resulting costs of increased health care.

In the Canadian province of Ontario, a child helmet law is widely ignored by children, parents and police alike. In the Borough of East York, Ontario, helmet use went up immediately following the law’s introduction but returned to the pre-law level within four years {14}{15}. Police forces are already stretched to the limit dealing with real crime and couldn't enforce the law even if they wanted to. This has a negative impact on attitudes toward the justice system It sends the wrong message to young Canadians who already ignore much more important requirements such as the nighttime lighting law.

It is difficult to see anything but harm arising out of helmet laws. Physician, Dr. Thomas Demarco sees helmet laws as very damaging. He expressed his views in an article originally published in the Journal of the Canadian Medical Association.

15. What is the most effective way of reducing cycling injuries?

There's no particular epidemic of injuries from cycling, but unnecessary injuries are being incurred because of poor cyclist judgement. Without a doubt, the most effective way of avoiding injuries are those measures which focus on accident prevention. The primary accident prevention measure is skills training, particularly for children. It is 80% effective in reducing risk. You can't get better advice than that offered by John Forester in his book, Effective Cycling {7}:

"riding so you are less likely to get into accident situations is the first safety measure;
watchfulness and skill in escaping them is the second."

If cyclists make an effort to acquire the basic skills and abide by these two principles, their risk of being involved in serious accidents is miniscule.

Cyclist education programs are available in most countries. The US national program - Effective Cycling - and its Canadian equivalent - CAN-BIKE are both based on the teachings of John Forester. Such programs are usually sponsored by national cycling organizations and delivered at the local level by bike clubs and other cycling organizations.

SOURCES & SITES

{1} Adams, John, Risk, 1995, UCL Press, ISBN 1 85728 068 7 PB

{2} Aultman-Hall, L., and Adams, M.F., Sidewalk Bicycling Safety Issues. Paper presented to the Transportation Research Board, 77th Annual Meeting, Washington, D.C., January 1998.

{3} British Medical Association, Cycling towards Health & Safety, 1992, Oxford University Press, ISBN 0-10-286151-4

{4} DiGuisseppi CG, Rivara FP, Koepsell TD, Bicycle helmet use by children. Evaluation of a community-wide helmet campaign, JAMA 1989; 262: 2256-61.

{5} Failure Analysis Associates Inc, Comparative Risk of Different Activities, Design News, October 4, 1993

{6}Farris C, Spaite DW, Criss EA, Valenzuela TD, Meislin HW, Observational evaluation of compliance with traffic regulations among helmeted and nonhelmeted bicyclists, Ann Emerg Med 1997 May;29(5):625-9

{7} Forester, John, Effective Cycling, 1993, MIT Press

{7a} Henderson M. The effectiveness of bicycle helmets: a review, report for Motor Accidents Authority of New South Wales

{7b} Hillman, M., Cycle Helmets, the Case For and Against, 1993, Policy Studies Institute Report 752, ISBN 0-85374-602-8

{8} Mills NJ, Gilchrist A, Oblique impact testing of bicycle helmets, Int Journal of Impact Engineering, 2008;35(9):1075-1086

{8a} Morgan D.E., Szabo L.S. Improved Shock Absorbing Liner for Helmets, Australian Transport Safety Bureau, July 2001, Australian Transport Safety Bureau, PO Box 967, CIVIC SQUARE ACT 2608

{9} Robinson, B., Is there Any Reliable Evidence That Australian Helmet Legislation Works?, paper presented to Velo Australis, Freemantle, Australia, October 1996

{10} Robinson, D.L., Head Injuries & Bicycle Helmet Laws, 1996, Accident Analysis Prevention, vol 28, pp463 - 475

{11} Scuffham, P.A., Langley, J. D., Trend in Cycling Injuries in New Zealand Under Voluntary Helmet Use, 1997, Accident Analysis and Prevention, Vol 29, No 1

{12} Thompson, R., Rivara, F., & Thompson, D., A Case-Control Study of Effectiveness of Bicycle Safety Helmets, New England Journal of Medicine - May 25, 1989

{13} Wilde, J. S., Target Risk, 1994, PDE Publications

{14}  Macpherson A, Macarthur C, To T, Chipman M, Wright J, Parkin P. Economic disparity in bicycle helmet use by children six years after the introduction of legislation. Injury Prevention 2006;12:231-35.

{15} Macpherson A, Parkin P, To T. Mandatory helmet legislation and children's exposure to cycling. Injury Prevention 2001;7:228-30.

Full Source List

Other Web Resources

§         Cyclist Rights Action Group - carries out research in its fight to reverse Australian
helmet laws. Contains comprehensive coverage of impact of Australian laws.

§         Dorothy L. Robinson's papers show results of safety measures
on cyclists and other road users in Australia:

"Cycle Helmet Laws - facts, figures, and consequences"
"Helmet Laws and Health"
Head Injuries in Western Australia

§         Australian Chris Gillham has analyzed public records to determine the
impact on health of Western Australia's compulsory bicycle helmet law.

§         British expert witness in bicycle crash litigation, John Franklin
has material on his web site.

§         An international coalition of doctors, scientists, engineers and other experts make up the Bicycle Helmet Research Foundation . Its web site contains a comprehensive collection of helmet research and opinion.

§         Locations with Helmet Laws - mostly in the USA

E-mail your feedback to: The Vehicular Cyclist