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Bicycle helmet

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Bicycle helmet

A bicycle helmet is a helmet intended to be worn while riding a bicycle. They are designed to attenuate impacts to the head of a cyclist in falls while minimizing side effects such as interference with peripheral vision.[1] They are specified to withstand simple falls onto a flat surface without other vehicles being involved.[2][3] There is intense and occasionally bitter debate on whether helmet use does offer significant reduction of the chance of a head injury.

A cycle helmet should be light in weight and should provide adequate ventilation, because cycling can be an intense aerobic activity which significantly raises body temperature and the head in particular needs to be able to regulate its temperature.

About helmets

Design and materials

There are two main types of helmet: hard shell and soft/micro shell (no-shell helmets are now rare). In both types impact energy is absorbed as a stiff foam liner is crushed, up to the point where the liner is crushed to its minimum thickness, or the helmet shatters, after which no further energy is absorbed. Collision energy varies with the square of impact speed: a typical helmet will absorb the energy of a fall from a bicycle, an impact speed of around 12mph (20km/h). It will only reduce the energy of a 30 mph (48km/h) impact to 27.5 mph (44km/h), and even this will be compromised if the helmet fails. This energy calculation is based on the standards, which take no account of the weight of the rider's body, which may be a factor in headfirst falls.

As a subsidiary effect they also spread point impacts over a wider area of the skull. Hard shell helmets do this better, but are heavier and less well ventilated. They are more common among stunt riders than road riders or mountain bikers. Additionally, the helmet will reduce superficial injuries to the scalp. Hard shell helmets can also reduce the likelihood of penetrating impacts although these are very rare.

The key component of most modern bicycle helmets is a layer of expanded polystyrene (EPS), essentially the plastic foam material used to make inexpensive picnic coolers. This material is sacrificed in an accident, being crushed as it absorbs a major impact. Bicycle helmets should always be discarded after any accident.

Helmets are most effective in straight line, or linear, blows to the head at moderate speed. Helmets are not well designed to deal with high speed impacts or rotational stresses (crashes that are not centred, and involve rotation of the head). They are not designed to provide adequate protection for a collision involving another moving vehicle, (e.g. a car).

A common misunderstanding is to assume that a broken helmet has prevented some serious injury. Helmets are designed to crush without breaking; EPS absorbs little energy in brittle failure and once it fails no further energy is absorbed. To prevent breakage, the foam in the helmets is reinforced inside with plastic netting to keep the foam together.

History

"Hairnet" helmet

Prior to the mid-1970s, the dominant form of helmet was the leather "hairnet" style, mainly used by racing cyclists. This offered minimal impact protection and acceptable protection from scrapes and cuts. In countries with long traditions of utility cycling, nearly all cyclists did not and still do not wear helmets. The use of helmet by non-racing cyclists began in the U.S. in the 1970s. After many decades of where cycles were regarded as children's toys, many American adults took up cycling during and after the bike boom of the 1970s. Two of the first modern bicycle helmets were made by MSR, a manufacturer of mountaineering equipment, and Bell Sports, a manufacturer of helmets for auto racing and motorcycles. These helmets were a spinoff from the development of expanded polystyrene (EPS) foam liners for motorcycling and motorsport helmets, and had hard polycarbonate plastic shells. The bicycle helmet arm of Bell was split off in 1991 as Bell Sports, having completely overtaken the motorcycle and motor sports helmet business.

The first commercially successful purpose-designed bicycle helmet was the Bell Biker, a polystyrene-lined hard shell released in 1975. At the time there was no appropriate standard; the only applicable one, from Snell, would be passed only by a light open-face motorcycle helmet. Over time the design was refined and by 1983 Bell were making the V1-Pro, the first polystyrene helmet intended for racing use. In 1984 Bell produced the Li'l Bell Shell, a no-shell children's helmet. These early helmets had little ventilation.

1985 saw the introduction of Snell B85, the first widely-adopted standard for bicycle helmets; this has subsequently been refined into B90 and B95 (see Standards below). At this time helmets were almost all either hard shell or no-shell (perhaps with a vacuum-formed plastic cover). Ventilation was still minimal due mainly to technical limitations of the foams and shells in use.

A Giro Atmos helmet, showing seamless in-mould microshell construction.

Around 1990 a new construction technique was invented: in-mould microshell. A very thin shell was incorporated during the moulding process. This rapidly became the dominant technology, allowing for larger vents and more complex shapes than hard shells.

Hard shells declined rapidly among the general cyclist population during the 1990s, almost disappearing by the end of the decade, but remain popular with BMX riders as well as inline skaters and skateboarders.

The late 1990s and early 2000s saw advances in retention and fitting systems, replacing the old system of varying thickness pads with cradles which adjust quite precisely to the rider's head. This has also resulted in the back of the head being less covered by the helmet; impacts to this region are rare, but it does make a modern bike helmet much less suitable for activities such as unicycling, skateboarding and inline skating, where falling over backwards is relatively common. Other helmets will be more suitable for these activities.

Since more advanced helmets began being used in the Tour de France, Carbon Fiber inserts have started to be used to increase strength and protection of the helmet. The Giro Atmos and the Bell Alchera are among the first to use carbon fiber.

Helmet regulations in cycling sport

Historically, road cycling regulations set by the sport's ruling body, Union Cycliste Internationale (UCI), did not require helmet use, leaving the matter to individual preferences and local traffic laws. The majority of professional cyclists chose not to wear helmets, citing discomfort and claiming that helmet weight would put them in a disadvantage during uphill sections of the race.

The first serious attempt by the UCI to introduce mandatory helmet use in 1991 was met with strong opposition from the riders.[4] An attempt to enforce the rule at the 1991 Paris-Nice race resulted in riders' strike, forcing the UCI to abandon the idea.

While voluntary helmet use in professional ranks rose somewhat in the 1990s, the turning point in helmet policy was the March 2003 death of Kazakh Andrei Kivilev. Some officials within UCI had been trying to re-establish a helmet rule, and used this incident to push through the change, initially claiming that it was for insurance reasons although the insurers subsequently denied this. The new rules were introduced on May 5, 2003[5], with the 2003 Giro d'Italia being the first major race affected. The 2003 rules allowed for discarding the helmets during final climbs of at least 5 kilometres in length;[6] subsequent revisions made helmet use mandatory at all times.

No studies have been published yet into whether injuries have reduced as a result.

Standards

In the United States the Snell Memorial Foundation, an organization initially established to create standards for motorcycle and auto-racing helmets, implemented one of the first standards. The American National Standards Institute (ANSI) created a standard called ANSI Z80.4 in 1984. Later, the United States Consumer Product Safety Commission (CPSC) created its own mandatory standard for all bicycle helmets sold in the United States, which took effect in March 1999.

In the European Union the currently applicable standard is EN 1078:1997. In the UK this replaces BS 6863:1989.

The CPSC and EN1078 standards are lower than the Snell B95 (and B90) standard; Snell helmet standards are externally verified, with each helmet traceable by unique serial number. EN 1078 is also externally validated, but lacks Snell's traceability. The most common standard in the US, CPSC, is self-certified by the manufacturers. It is generally true to say that Snell standards are more exacting than other standards, and most helmets on sale these days will not meet them (no current Bell brand helmet is Snell certified, some Specialized ones are – the Snell Memorial Foundation website includes a list of certified helmets).

In 1990 the Consumers' Association (UK) market survey showed that around 90% of helmets on sale were Snell B90 certified. By their 1998 survey the number of Snell certified helmets was around zero. Hard shells declined rapidly among the general cyclist population over this period, almost disappearing by the end of the decade, but remained more popular with BMX riders as well as inline skaters and skateboarders.

Although helmet standards have weakened over time[3] there is no data on which to base an assessment of how this has affected the design goal of mitigating minor injuries. Minor injuries are substantially under-reported and it is difficult if not impossible to effectively measure such injuries on a meaningful scale.

The major source of serious injury to cyclists is impact with motor vehicles. Current helmet standards are inadequate to protect against such collisions, the energies involved are routinely in excess of the rated capacity of the best motorsport helmets. Helmets designed to higher standards have generally not sold well, while helmets designed to even lower standards have sold well[11]. A helmet's ability to absorb energy could be improved by increasing the volume of polystyrene, but this would make it thicker, heavier, and hotter to wear. The trend is towards thinner helmets with many large vents. This trend to lower standards has been noted in some of the studies[7] It is relatively common for helmets to fail on test, and some helmets on sale are not certified to any accepted standard.[8] The most widely-cited pro-helmet studies were conducted when most helmets were of a hard-shell construction; these are now rare outside of niche applications such as BMX.

Most of the standards are designed to be passable using current designs and materials rather than to set a certain minimum safety standard. Tests typically involve weighting the helmets and dropping them onto anvils with flat, hemispherical and cornered (comparable to a kerbstone) shapes.[12] Since the hemispherical and cornered anvils present the most difficult tests to pass, they are tested with a shorter drop, although there is no reason in practical riding why a person falling onto a flat surface would not fall as far as someone hitting a round object.

Proper fit

It is important that a helmet should fit the cyclist properly – according to research most helmets (well over 90% [9]) have been found to be incorrectly fitted. Efficacy of incorrectly fitted helmets is reckoned to be much lower; one estimate states that risk is increased almost twofold[10].

Most manufacturers provide a range of sizes ranging from children's to adult with additional variations from small to medium to large. The correct size is important. Some adjustment can usually be made using different thickness foam pads. Helmets are held on the head with nylon straps, which must be adjusted to fit the individual. This can be difficult to achieve, depending on the design. Most helmets will have multiple adjustment points on the strap to allow both strap and helmet to be correctly positioned. Additionally, some helmets have adjustable cradles which fit the helmet to the occipital region of the skull. These provide no protection, only fit, so helmets with this type of adjustment are unsuitable for roller skating, stunts, skateboarding and unicycling.

The helmet should sit level on the cyclists head with only a couple of finger-widths between eyebrow and the helmet brim. The strap should sit at the back of the lower jaw, against the throat, and be sufficiently tight that the helmet does not move on the head. It should not be possible to insert more than one finger's thickness between the strap and the throat.

The helmet debate; contested evidence, contested values

Do helmets work? Contradictory research evidence

File:Fahrradpark.jpg
Many areas with low helmet use have better bicycle safety.

Evidence for the efficacy of helmets in preventing serious injury is contradictory and inconclusive. The evidence comes from two main types of observational study:

  • case-control studies, in which cyclists who have injured their heads ("cases"), and cyclists who have not ("controls"), are compared. Known problems with this type of study design include confounding (attributing benefits from differences in behaviour to differences in helmet choice), and reporting errors (people falsely reporting helmet use).[11] Such studies consistently find that cases of head injury report a lower rate of helmet-wearing than controls who have injured other parts of the body.[12] This has been taken as strong evidence that cycle helmets are beneficial in a crash. The most widely-quoted case-control study, by Thompson, Rivara, and Thompson, reported an 85% reduction in the risk of head injury by using a helmet. There are many criticisms of this study,[13] including use of an inappropriate control group. Re-analysis of the Thompson, Rivara and Thompson data, substituting helmet wearing rates from co-author Rivara's contemporaneous street counts[14], reduces the calculated benefit to below the level of statistical significance. In another study, helmet users also seemed to be protected against severe injuries to the lower body. "We conclude that helmet non-use is strongly associated with severe injuries in this study population. This is true even when the patients without major head injuries are analyzed as a group.[15] This is taken as evidence that the cases and controls in this study have very different types of injury even if there is no actual effect of helmets, and therefore that conclusions about the protective effect of helmets are unlikely to be accurate.
  • Time-trend analyses compare changes in helmet use and injury rates in populations over time, most validly where helmet laws have resulted in large changes in a short time. Potential weaknesses of this type of study include: simultaneous changes in the road environment (e.g. drink-drive campaigns); inaccuracy of exposure estimates (numbers cycling, distance cycled etc.), changes in the definitions of the data collected, failure to analyse control groups, and failure to analyse long-term trends. Authors of literature reviews do not agree on how studies should be selected for analysis, nor on what summary statistics are most relevant. Robinson's review of jurisdictions where helmet use increased by 40% or more following compulsion showed that "enforced helmet laws discourage cycling but produce no obvious response in percentage of head injuries".[16] This study has been the subject of vigorous debate. [17] [18] [19] The most recent review, by Macpherson and Spinks, includes two original papers, neither of which was included in Robinson's review, and concludes that "Bicycle helmet legislation appears to be effective in increasing helmet use and decreasing head injury rates in the populations for which it is implemented. However, there are very few high quality evaluative studies that measure these outcomes, and none that reported data on an possible declines in bicycle use."[20]

There are many other studies. The largest, covering eight million cyclist injuries over 15 years, showed no effect on serious injuries and a small but significant increase in risk of fatality.[21] Different analyses of the same data can produce different results. For example, Scuffham analysed data on the New Zealand helmet law in 1995 and concluded that, after taking into account long-term trends, the laws had no measurable effect.[22] His subsequent re-analysis without accounting for the long-term trends showed a small benefit.[23] Scuffham's later cost-benefit analysis of the New Zealand helmet law showed that the cost of helmets outweighed the savings in injuries, even taking the most optimistic estimate of injuries prevented.[24]

Overall, according to CTC, the UK's national cyclists organisation, "the evidence currently available is complex and full of contradictions, providing at least as much support for those who are sceptical as for those who swear by them."[25]

Groups and attitudes

There is a long-running argument over the use, promotion, and compulsion of cycle helmets. Most heated controversy surrounds laws making helmet use compulsory. Disagreements arise from the contested research, above, and from different assessments of what issues are relevant and important. Cyclists usually find their own comfort, expense, independence, and convenience to be relevant, and pro-cycling organizations are concerned to increase the total amount of bicycling and therefore to promote its safe and healthy nature, but these issues are seldom mentioned by pro-compulsion campaigners. Many of the most vocal proponents of helmets are not themselves cyclists.[26] Received opinion in some English-speaking countries is that bicycle helmets are useful and that every cyclist should wear one. In other countries, often those in which cycling is commoner and safer, helmets are seldom used or even considered. Controversy is fuelled by support given to the pro-compulsion movement by Bell Sports in particular.[27]

Various organizations have taken up definite positions on the issue, not always based on a full review of the evidence. For example, the British Medical Association used to be against helmet compulsion, following an extensive review of the evidence in 1999. In late 2004 the BMA's Board of Science and Education adopted a 'position' calling on the UK government to introduce cycle helmet legislation, and this was confirmed at the 2005 Annual Representative Meeting following fifteen minutes of debate (transcript). The BMA's new position uses statistics provided by the British political lobby group, the Bicycle Helmet Initiative Trust, and excludes from consideration the majority of conflicting evidence, including the BMA's own previous work. Several provably wrong figures were removed after initial publication, but the review is still viewed as distorted, excluding not only references included in the 1999 BMA study, but the 1999 study itself. Debate continues within the BMA.

Much of the research is partisan in one way or another. Significant helmet promotion preceded epidemiological studies evaluating the effectiveness of bicycle helmets in bicycle crashes.[28][29] Dismissing concerns in 1996 that helmets should be shown to actually reduce injury rates, two pro-helmet doctors asked "How robust must the evidence be when the benefits of wearing helmets are so patently obvious? What is the downside to wearing a helmet, other than the mussing of Minerva's hair?".[30] One of these, himself a cyclist, started his "career of advocacy" in 1972 and is now editor of an academic journal on injury prevention.[31] In this position he has found "tiresome" academic argument that helmet wearing is useless.[32][33][34][35] Rivara was already engaged in surveying and lobbying for helmet use before the influential Thompson, Rivara and Thompson case-control study was commenced in 1989[14], while the report by Thompson, Rivara and Thompson for the Cochrane review has been criticised for being dominated by their own work. Rodgers re-analysed data which supposedly showed helmets to be effective; he found data errors and methodological weaknesses so serious that in fact the data showed "bicycle-related fatalities are positively and significantly associated with increased helmet use".[36] One report concluding that helmet use was associated with a 60% reduction in injuries was found to be in error due to a simple statistical error; correcting the error results in a claimed efficacy of 186%; despite this the authors continue to assert that the results stand.[37] A report commissioned by the UK Government was supportive of cycle helmet promotion[38] but dismissed much of the contradictory evidence with minimal examination, and the principal authors were associated with a programme of the Child Accident Prevention Trust (CAPT), which is strongly pro-helmet.[39] Curnow, author of papers on helmets and traumatic brain injury, has also published criticism of pro-helmet research.[40]

The view of the UK cyclists' club, CTC, is that analyses of the relative merits of different bike safety interventions put helmets low down,[41] because no helmet will reduce the probability of crashing (and there is some evidence that helmets may increase this likelihood[42][43][44]). Proactive measures including bike maintenance and riding skills are far more important.[45] Although the link is not causal, it is observed that the countries with the best cycle safety records (Denmark and the Netherlands) have among the lowest levels of helmet use.[46] Their bicycle safety record is generally attributed to public awareness and understanding of cyclists, education, and to some extent separation from motor traffic.

Safety in numbers; reduction in bicycle participation after helmet laws

Mandatory bicycle helmet laws have been linked to a reduction in the number of cyclists. For example, when mandatory bicycle helmet laws were enacted in Australia, slightly more than one third of bare-headed cyclists ceased to ride their bicycles frequently.[47] The reduction in the number of cyclists is likely to harm the health of the population more than any possible protection from injury.[48] The long term health benefits of bicycle use are manifold and extensively documented, and so any reduction in bicycling will likely have a negative impact on the overall health of a population. [49] However, it has been suggested that a fall in the number of bicyclists in the 1990s may simply reflect an increase in in-line skating or other recreational activities,[18] or the evidence that helmet promotion deters cycling has been simply denied.[20]

Several mechanisms by which cycle helmet promotion or compulsion may deter cycling have been suggested. Helmets and their promotion may reinforce the misconception that bicycling is more dangerous than traveling by passenger car.[50] Cycle helmets cost money and may make cycling less convenient; they are bulky and often cannot be stored securely with bikes. They are incompatible with some hairstyles, forcing bicycle users to recreate their hairstyle after each journey. Finally, bicycle "crash-helmets" have been seen as ridiculous. For example, in the 2006 film The Benchwarmers, the character Clark — played by Jon Heder — sports a bicycle crash helmet as an accessory prop to highlight his lack of social skills and physical coordination.

A reduction in cycling may lead to an increased risk for the cyclists remaining on the road, due to a "safety in numbers" effect.[51] According to one study, the probability of an individual cyclist being struck by a motorist declines with the 0.6 power of the number of cyclists on the road.[52] This means that if the number of cyclists on the road doubles, then the average individual cyclist can ride for an additional 50% of the time without increasing his probability of being struck. It is thought that the increased frequency of motorist-cyclist interaction creates more aware motorists.

Helmets and increased risk of injury

Association with increased risk has been reported.[53][21][15] Although the head injury rate in the US rose by 40% as helmet use rose from 18% to 50%, this does not necessarily mean that helmets themselves increase risk. In fact, a range of theories exist to explain the association between helmet use and accidents, including:

  • Risk compensation: helmeted cyclists may ride less carefully; this is well supported by evidence for other road safety interventions such as seat belts and antilock brakes.[43][44] Risk compensation by children in relation to safety equipment has been demonstrated.[42]
  • Recent evidence from England found that vehicles passed helmeted cyclists with measurably less clearance (8.5 cm) than that given to unhelmeted cyclists (out of an average total passing distance of 1.2 to 1.3 metres), indicating risk compensation by motorists.[54]
  • Poor fitting

Recent research on traumatic brain injury adds further confusion, suggesting that the major causes of permanent intellectual disablement and death may well be torsional forces leading to diffuse axonal injury (DAI), a form of injury which helmets cannot mitigate and may make worse.[55] Helmets may increase the torsional forces by increasing the distance from the extremities of the helmet to the centre of the spine, compared to the distance without a helmet.

Some studies suggesting increased risk from helmet use may give spurious results, as mentioned for case-control studies above:

  • Some injured cyclists may say that they were wearing a helmet when in fact they were not. If these figures are compared to the observed percentage of helmet users on the roads, they may suggest incorrectly that helmet users are more likely to have accidents.

Promotion and compulsion; situation and arguments

Many believe that a helmet can save a cyclist's life, an idea which is repeatedly asserted in debate. The UK minister of transport knew of no evidence for this claim and mass helmet use has not demonstrably reduced the number of cyclists' deaths or serious head injuries.[56][16] Use of cycling helmets is supported by numerous groups in the United States, including the American Medical Association[57] and the American National Safety Council [58]. In 1998 the European Cyclists' Federation adopted a position paper rejecting compulsory helmet laws as being likely to have greater negative rather than positive health effects [59]. The World Health Organization is currently studying the results of the latest Cochrane review of bicycle helmet legislation before forming a view on whether to support compulsion.

Helmet use has increased significantly in many, but not most, jurisdictions since the 1980s, primarily because of helmet promotion and compulsion laws. The following countries have mandatory helmet laws, in at least one jurisdiction, for either minors only, or for all riders: Australia, Canada, Finland, Iceland, Israel,[60] Sweden, USA, and New Zealand. In the U.S. 37 states have mandatory helmet laws.[61]

Promotion of helmets raises further issues. Helmet promoters routinely make claims which manufacturers cannot, due to restrictions on advertising claims. Promotion campaigns are often supported and/or funded by manufacturers. Bell, one major helmet manufacturer, supports both helmet promotion and, through its Legislative Assistance Programme, laws. From the point of view of cycle activists, the major problem with helmet promotion, is that in order to present the idea of a "problem" to match the solution they present, promoters tend to overstate the dangers of cycling. Cycling is, according to the evidence, no more dangerous than being a pedestrian. In fact, helmet compulsion in cars would be far more effective at reducing injuries than on bicycles.[62][63][64]

Cyclists' representative groups complain that focus on helmets diverts attention from other issues which are much more important for improving bicycle safety, such as road danger reduction, training, roadcraft, and bicycle maintenance[59][65] . Of 28 publicly funded cycle safety interventions listed in a report in 2002, 24 were helmet promotions. For context, one evaluation of the relative merits of different cycle safety interventions estimated that 27% of cyclist casualties could be prevented by various measures, of which just 1% could be achieved through a combination of bicycle engineering and helmet use.[citation needed]

Data from around the world shows that despite the optimistic claims for injury reduction made by their proponents, no helmet law currently in force has caused a demonstrable reduction in the proportion of head injuries among cyclists.[16] There are a number of possible explanations for this:

  • the case-control studies on which the laws are founded mainly compared the small proportion of cyclists who chose to wear helmets with those who do not; these cyclists show particularly safe riding habits.[66] It is suggested that this may account for much of the apparent effect of helmets seen in case-control studies, and that forcing a cyclist to wear a helmet will not make them behave like the kind of cyclist who wears one by choice
  • helmets are not designed to withstand motor vehicle impacts, but these account for most serious and almost all fatal cyclist injuries [44][59]
  • minor injury rates are seldom accurately recorded and often not recorded at all; any protective device would be expected to be much more effective against minor injuries, rapidly tailing off with severity. Although a few studies do claim that cycle helmets are more effective against serious than against minor injuries, it is possible that the efficacy figures cited are against a type of injury which subsequent routinely-collected statistics will not measure
  • Helmet laws tend to deter cycling; the theory of safety in numbers suggests that cycling becomes safer the more people who do it.

While a helmet may mitigate the effects of a fall or collision, other factors (such as maintenance, road conditions, and driver behaviour) may be more important for reducing the chance of such accidents in the first place. In general, "the value of bicycle helmets has been systematically overstated".[67]

The definition of injury is also open to debate, and injury figures are acknowledged to be inaccurate. Research by TRL and others shows that reporting of injuries is related to severity: fatal injuries are almost always reported, in the developed world, but 90% or more of lesser injuries go unreported. Helmets are most likely to be effective against lesser injuries. Pro-helmet studies routinely refer to prevention of traumatic brain injury, which has connotations of permanent intellectual disablement, but where sufficient data is provided it is found that the majority of the brain injuries in these studies are mild and transient concussion. A study of fatally injured cyclists found injuries of fatal severity to multiple organ systems were in sixteen of twenty riders, including six with no significant head injury. Four riders died of fatal injury to head alone and one of these was the only rider known to be wearing a safety helmet. His death resulted from a fall from a bicycle at moderate speed rather than collision with a motor vehicle.[68]

Cycling as a dangerous activity

Ordinary cycling is not demonstrably more dangerous than walking or driving,[69] yet no country promotes helmets for either of these modes (although there was an experiment in Japan with walking helmets for children, which demonstrated no measurable benefit).[70] Cycle helmet use correlates inversely with the level of cycling in a given country.[71]

Detailed analysis of hospital admissions data also fails to support the idea that cycling is unusually dangerous: a study in the UK found that the proportion of cyclist injuries which are head injuries is essentially the same as the proportion for pedestrians at 30.0% vs. 30.1%.[72]

Overall, cycling is beneficial to health – the benefits outweigh the risks by up to 20:1.[73] Critics assert that anything which jeopardises that benefit should be carefully weighed to ensure it is likely to achieve some meaningful benefit in turn. Thus far, no helmet law has been shown to do that.

References

  1. ^ Consumer Product Safety Commission. "Safety Standard for Bicycle Helmets" (pdf). Final Rule 16 CFR Part 1203. {{cite web}}: Unknown parameter |accessyear= ignored (|access-date= suggested) (help)
  2. ^ BS6863:1989, Pedal Cyclists' Helmets, British Standards Institution
  3. ^ a b Brian Walker. "Helmet standards and capabilities". Bicycle Helmet Research Foundation. Retrieved 2007-08-24.
  4. ^ DEATH OF CYCLIST ANDREI KIVILEV: DECLARATION BY THE INTERNATIONAL CYCLING UNION
  5. ^ MANDATORY WEAR OF HELMETS FOR THE ELITE CATEGORY
  6. ^ http://www.uci.ch/english/news/news_2002/20030502i.pdf
  7. ^ e.g. Vulcan, A.P., Cameron, M.H. & Watson, W.L., "Mandatory Bicycle Helmet Use: Experience in Victoria, Australia", World Journal of Surgery, Vol.16, No.3, (May/June 1992), pp.389–397.
  8. ^ Heads Up, Walker B., Cycle magazine (Cyclists' Touring Club) June 2005
  9. ^ Parkinson et al. (2003) PEDIATRICS Vol. 112 No. 2:320–323
  10. ^ Rivara et al. (1999) Injury Prevention 5: 194-197
  11. ^ Objective observation of helmet use is essential. British Medical Journal
  12. ^ [1] Thompson DC, Rivara FP, Thompson R. Helmets for preventing head and facial injuries in bicyclists. Cochrane Database of Systematic Reviews 1999, Issue 4. Art. No.: CD001855. DOI: 10.1002/14651858.CD001855.
  13. ^ BHRF
  14. ^ a b DiGuiseppi CG, Rivara FP, Koepsell TD, Polissar L. Bicycle helmet use by children. Evaluation of a community-wide helmet campaign. Journal of the American Medical Association 1989;262:2256-61.
  15. ^ a b A prospective analysis of injury severity among helmeted and non helmeted bicyclists involved in collisions with motor vehicles Spaite DW, Murphy M, Criss EA, Valenzuela TD, Meislin HW. 1991. Journal of Trauma: 1991 Nov;31(11):1510–6
  16. ^ a b c [2] No clear evidence from countries that have enforced the wearing of helmets. Robinson DL. BMJ 2006;332:722-725, doi:10.1136/bmj.332.7543.722-a
  17. ^ [3] Rapid Responses to D L Robinson
  18. ^ a b [4] BMJ 2006;332:725-726, doi:10.1136/bmj.332.7543.725 Arguments against helmet legislation are flawed. Hagel B, Macpherson A, Rivara FP, Pless B.
  19. ^ [5] Rapid Responses to Brent Hagel, Alison Macpherson, Frederick P Rivara, and Barry Pless
  20. ^ a b [6] Macpherson A, Spinks A. Bicycle helmet legislation for the uptake of helmet use and prevention of head injuries. Cochrane Database of Systematic Reviews 2007, Issue 2. Art. No.: CD005401. DOI: 10.1002/14651858.CD005401.pub2
  21. ^ a b Reducing Bicycle Accidents: A Reevaluation of the Impacts of the CPSC Bicycle Standard and Helmet Use Rodgers GB. 1988. Journal of Products Liability: 1988,11:307–317
  22. ^ Trends in cycle injury in New Zealand under voluntary helmet use Scuffham PA, Langley JD. 1997. Accident Analysis and Prevention: 1997 Jan;29(1):1–9
  23. ^ Head injuries to bicyclists and the New Zealand bicycle helmet law, Scuffham P, Alsop J, Cryer C, Langley JD. 2000. Accident Analysis and Prevention: 2000 Jul;32(4):565–73
  24. ^ New Zealand bicycle helmet law-do the costs outweigh the benefits? Taylor M, Scuffham P. 2002. Injury Prevention: 2002;8:317–320
  25. ^ CTC position paper on helmets
  26. ^ e.g. Angela Lee, chief executive of British helmet pressure group the Bicycle Helmet Initiative Trust, interviewed in BikeBiz in 2003
  27. ^ Helmet compulsion pressure group SafeKids acknowledges Bell Sports as a major sponsor.
  28. ^ "Injury-Control Recommendations: Bicycle Helmets". Centers for Disease control and Prevention. 1995-02-17. Retrieved 2007-07-27. {{cite web}}: Check date values in: |date= (help)
  29. ^ Richard's Bicycle Book. Richard Ballantine. Ballantine Press 1972.
  30. ^ http://www.bmj.com/cgi/content/full/313/7057/629/a Davis RM, Pless B. BMJ 1996;312:1310 (18 May)
  31. ^ http://injuryprevention.bmj.com/info/about.dtl accessed 22nd August 2007
  32. ^ http://injuryprevention.bmj.com/cgi/content/extract/13/2/73 Pless IB. A chronology of failed advocacy and frustration. Injury Prevention 2007;13:73-74; doi:10.1136/ip.2007.015776
  33. ^ http://injuryprevention.bmj.com/cgi/content/extract/12/6/353 Pless B. Are Editors free from bias? The special case of Letters to the Editor. Injury Prevention 2006; 12: 353-354
  34. ^ http://injuryprevention.bmj.com/cgi/eletters/12/6/353 Dorothy L Robinson. Good data and constructive debate can help resolve controversial issues. Injury Prevention. eletter 18 January 2007.
  35. ^ http://injuryprevention.bmj.com/cgi/eletters/12/6/353 Evidence on cycle helmets is contested, ambiguous and inconclusive. Peter Ward. Injury Prevention. eletter 2 January 2007.
  36. ^ Reducing bicycle accidents: A reevaluation of the impacts of the CPSC bicycle standard and helmet use. Rodgers, GB. J. Product Liability. Vol. 11, no. 4, pp. 307-317. 1988.
  37. ^ Trends in serious head injuries among English cyclists and pedestrians, Injury Prevention 2003; 9: 266–267 and responses
  38. ^ Bicycle helmets – a review of their effectiveness: a critical review of the literature Towner E, Dowswell T, Burkes M, Dickinson H, Towner J, Hayes M. 2002. Department for Transport: Road Safety Research Report 30
  39. ^ Critique of Road Safety Research Report 30
  40. ^ The Cochrane Collaboration and bicycle helmets Curnow WJ. 2005. Accident Analysis & Prevention: 2005;37(3):569–573
  41. ^ CTC Policy Handbook
  42. ^ a b Mok et al., Risk compensation in children's activities: A pilot study, Paediatric Child Health: Vol 9 No 5 May/June 2004 Cite error: The named reference "MOK" was defined multiple times with different content (see the help page).
  43. ^ a b John Adams, 1995, Risk, Routledge, ISBN 1-85728-068-7 — (Authoritative reference on risk compensation theory.) Cite error: The named reference "Risk" was defined multiple times with different content (see the help page).
  44. ^ a b c Death on the Streets: Cars and the mythology of road safety, Davis, 1993, ISBN 0-948135-46-8
  45. ^ Cyclecraft: Skilled Cycling Techniques for Adults. Franklin J. Stationery Office Books; 2Rev Ed edition 1997. ISBN 978-0117020511
  46. ^ http://www.cyclehelmets.org/index.html
  47. ^ [7] Komanoff (2001) Injury Prevention 7:343–344
  48. ^ Robinson (1996) Accident Analysis and Prevention 28:463–475
  49. ^ [8] Andersen LB, Schnohr P, Schroll M, Hein HO. All-cause mortality associated with physical activity during leisure time, work, sports, and cycling to work. Arch Intern Med 2000 Jun 12;160(11):1621-8.
  50. ^ [9]Estimates of Fatal Risk
  51. ^ [10] Safety in numbers: more walkers and bicyclists, safer walking and bicycling. Jacobsen PL. Injury Prevention 2003;9:205-209
  52. ^ Leden et al. (2000) Accident Analysis and Prevention 32(4):589–599
  53. ^ BMJ 2000;321:1582–5
  54. ^ http://www.drianwalker.com/overtaking/overtakingprobrief.pdf Drivers overtaking bicyclists: Objective data on the effects of riding position, helmet use, vehicle type and apparent gender. Ian Walker. Accident Analysis & Prevention Volume 39, Issue 2, March 2007, Pages 417-425 doi:10.1016/j.aap.2006.08.010
  55. ^ The efficacy of bicycle helmets against brain injury, Curnow WJ. 2003. Accident Analysis and Prevention: 2003,35:287–292
  56. ^ Letter from David Jamieson, MP, minister of state for transport, to Michael Jack, MP
  57. ^ AMA
  58. ^ http://www.nsc.org/library/facts/helmets.htm
  59. ^ a b c Improving Bicycle Safety - Without making helmet-use compulsory, European Cyclists' Federation 1998
  60. ^ Knesset passes controversial law requiring cyclists to wear helmets Haaretz, 25 July 2007
  61. ^ http://www.helmets.org/mandator.htm Helmet Laws for Bicycle Riders
  62. ^ Bicycle Helmet Research Foundation
  63. ^ Kennedy A. The pattern of injury in fatal pedal cycle accidents and the possible benefits of cycle helmets. British Journal of Sports Medicine, 1996 Jun;30(2):130–3.
  64. ^ McLean AJ, Fildes BN, Kloeden CN, Digges KH, Anderson RWG, Moore VM. Prevention of head injuries to car occupants: an investigation of interior padding options. Federal Office of Road Safety, Report CR160.
  65. ^ http://www.ctc.org.uk/DesktopDefault.aspx?TabID=4688 Helmet policy of the CTC
  66. ^ 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
  67. ^ Hansen P, Scuffham PA, Aust J Public Health: 1995 Oct;19(5):450–4
  68. ^ Fatal injuries to bicycle riders in Auckland. Sage MD. 1985. NZ Med J: 25 Dec 1985 Vol 98 No 793
  69. ^ Traffic Engineering & Control Dec 2002 pp352–6
  70. ^ Effectiveness of Wearing Pedestrian Helmets while Walking from Home to School, Tatsuhiro Yamanaka, and Arata Ogihara. Paper presented by Yamanaka at Melbourne Injury Prevention and Control Conference, February 1996
  71. ^ http:/www.cyclehelmets.org/index.html cyclehelmets.org
  72. ^ Data supplied to CTC by UK Department of Health
  73. ^ Hillman, 1999

Case studies/risk

  • Thompson, R., Rivara, F. and Thompson, D. (1989), A Case-Control Study of the Effectiveness of Bicycle Safety Helmets, New England Journal of Medicine, 25 May, 320:21, 1361–67 Abstract — (The most widely cited pro-helmet study.)
  • Bicycle Helmet Research Foundation, "Commentary on A Case-Control Study of the Effectiveness of Bicycle Safety Helmets", accessed 21st June 2006
  • Scuffham Trends in cycle injury in New Zealand under voluntary helmet use, Langley. Accident Analysis and Prevention, Vol 29:1, 1997 — (Showed no benefit from large-scale increases in helmet use.)
  • John Adams, 1995, Risk, Routledge, ISBN 1-85728-068-7 — (Authoritative reference on risk compensation theory.)

Helmet Fit

  • Parkinson, Gregory and Hike, Kelly E. (2003), Bicycle Helmet Assessment During Well Visits Reveals Severe Shortcomings in Condition and Fit, [13] Pediatrics, 2 August 2003 Vol. 112 No. 2, pp. 320–323 — (Showed that correct fitting is an exception.)

Compulsion Laws

Bicycling as traffic books

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