Bicycle helmet
The dominant form of the helmet up to the 1970s was the "hairnet" style, an open construction made of rubber bars covered in leather.
After many decades when bicycles were regarded largely as children's toys, many American adults took up cycling during and after the bike boom of the 1970s.
The first commercially successful purpose-designed bicycle helmet was the Bell Biker, a polystyrene-lined hard shell released in 1975.
Use of hard shells declined rapidly among the general cyclist population during the 1990s, almost disappearing from road and cross country mountain bike helmets by the end of the decade, but remaining popular with BMX riders and more aggressive mountain bike disciplines such as downhill riding.
Some modern road and track racing bicycle helmets have a long tapering back end for streamlining.
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.
[11][12] The rotational accelerations that arise in bicycle accidents can be large enough to cause concussions, diffuse axonal injury and subdural haematoma.
Efficacy of incorrectly fitted helmets is reckoned to be much lower; one estimate states that risk is increased almost twofold.
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.
[19] Studies from China, Denmark, the Netherlands and the United Kingdom show that regular cyclists live longer because the health effects far outweigh the risk of crashes.
[27] De Jong developed a mathematical model to evaluate the health-risk trade-offs of all-age mandatory helmet laws, if they were to be introduced in various North American and Western European countries.
However, Newbold stressed that there were many parameters to these models which require further research to properly quantitate, and that results should be considered provisional rather than definitive.
The authors concluded that "although the findings do not support the existence of a strong risk compensation mechanism among helmeted cyclists, this possibility cannot be ruled out.
[37][38] An experimental study found that children negotiating an obstacle course on foot went faster and took more risks when wearing safety gear (including helmets).
[41] An initial re-analysis of these data by other investigators agreed that with the 8.5 cm finding, but argued that there were not more "close passes" (which they defined as under 1 metre of clearance).
[45][46] The main target markets seem to be the US and Europe, with 90 percent of US counterfeit seizures coming from Hong Kong and China.
[48] European Standard EN 1080, which uses a weak retention system designed to open under load, was published in 1997 to address this problem.
[49] To avoid serious accidents, parents and carers should take care to ensure that children do not wear bicycle helmets during unsupervised play, or when using climbing equipment.
These include the World Health Organization,[59] the British Medical Association,[60][61] the American Medical Association,[62] the American College of Emergency Physicians,[63] the Canadian Paediatric Society,[64] the Canadian Academy of Sport and Exercise Medicine,[65] and the Royal Australasian College of Surgeons.
[25][26] Mayer Hillman, a transport and road safety analyst from the UK, does not support the use of helmets, reasoning that they are of very limited value in the event of a collision with a car, that risk compensation negates their protective effect and because he feels their promotion implicitly shifts responsibility of care to the cyclist.
[76][77] He also cautions against placing the recommendations of surgeons above other expert opinion in the debate, comparing it to drawing conclusions on whether it is worthwhile to buy lottery tickets by sampling only a group of prizewinners.
[78] The prominent UK-based cycling activist John Franklin is skeptical of the merits of helmets, regarding proactive measures including bike maintenance and riding skills as being more important.
"[82] The Dutch Fietsersbond (Cyclists' Union) summarised existing evidence and concluded that a compulsory helmet law (for utility cyclists) would have a negative impact on population health: "Helmet laws save a few brains, but destroy a lot of hearts".
The following countries have mandatory helmet laws, in at least one jurisdiction, for either minors only, or for all riders: Australia, Canada, Czech Republic, Finland, Iceland, New Zealand, Sweden, and the United States.
[90] Although a causal link is not proven, it is observed that the countries with the best cycle safety records (Denmark and the Netherlands) have among the lowest levels of helmet use.
They also mention the possibility that helmets would make cycling more dangerous by giving cyclists a false sense of safety and thus encouraging riskier riding behavior.
