Bicycle helmet

from Wikipedia, the free encyclopedia
Bicycle helmet (micro-shell helmet)

A bicycle helmet (in Swiss also Velohelm ) is head protection for cyclists , which is intended to reduce the forces acting on their skull in an accident in order to prevent or lessen injuries. It is one of the passive road safety facilities .

history

Cyclists as well as recreational cyclists originally rode without headgear or only with a shaded peaked cap . Hard shell helmets were occasionally used in races from around 1920, which corresponded to the old half-shell helmets of motorcyclists.

From the 1960s to the 1990s, amateur cycling enthusiasts only wore a crash ring (also: crash cap ). The filled hoses made of leather and running from the front to the back of the head lay directly on the head. In contrast to helmets, the flexible construction was often foldable or foldable to a smaller format. Due to the flexible construction, only a low protective effect is assumed for the camber ring.

Helmets for amateur athletes appeared in the 1970s, in Germany this was in particular the “Trott helmet” developed in 1968 by Karl-Heinz Trott, the father of the amateur cyclist Wilfried Trott . Bicycle helmets became more widespread in cycling after the death of Fabio Casartelli from a head injury caused by a fall at the Tour de France in 1995 and then with the introduction of mandatory bicycle helmets by the UCI in 2003.

The potential for aerodynamic improvements in head flow was recognized earlier and the design of cyclist helmets, especially for time trials and track cyclists, was accompanied by wind tunnel tests.

A growing distribution of bicycle helmets outside of sport began in the late 1980s. The first mandatory helmet laws came in the early 1990s.

Structure and mode of operation

One distinguishes between:

Micro-shell helmets
have a thin plastic coating and are the most common. They have a smooth surface that is supposed to make it easier to slide off the ground and also have ventilation openings so that the wearer sweats less.
Hard shell helmets
have a hard plastic coating around the foam. Due to their high weight, they can only be found practically in the downhill area. Often they are also equipped with a chin guard as face protection. The hard, smooth surface offers protection against mechanical impact and makes it easier to slide off the ground.
Soft-shell helmets (softshell helmets)
consist only of a shell made of rigid foam. They were mainly used as children's helmets. Soft-shell helmets are no longer state-of-the-art and, according to experts, should no longer be used. The soft surface does not slide off the ground in the event of an impact, which increases the risk of whiplash .

Mechanical mode of action

Basics

When the helmet impacts, the foam (or hard foam) of the helmet fulfills the function of a crumple zone and absorbs energy through compression or breakage. In this way, the acceleration exerted on the brain is reduced and the likelihood of fracture of the skull bone is reduced. With hard shell helmets, the shell distributes the force of the impact over a larger area, which also reduces the likelihood of a fracture of the skull bone. The function of a protective cover can prevent or at least reduce abrasions, lacerations and bruises in the area under the helmet.

In modern helmets, the shell of the helmet is fixed to the head with a chinstrap hung at several points and flexible elements of the helmet lining. A loose fit or a shifting of the helmet, which would impair its protective effect, are prevented. Incorrectly used or improperly fitted helmets have a lower protective effect or can even be switched off completely.

In accident situations in which the helmet slides on the ground or along obstacles, the coefficient of sliding friction of the helmet surface has a significant influence on the amount of forces and moments that occur. With hard shell helmets, this coefficient of sliding friction is low so that the forces that occur can be diverted. With soft-shell helmets, an interlocking with the ground can occur, which increases the forces and moments that occur enormously. For this reason, the helmet manufacturers have abandoned the construction principle of soft-shell helmets.

Due to the energy it absorbs, a bicycle helmet is permanently deformed in the event of a hard impact and should not be used any longer because it can no longer fulfill its protective function. Some helmet manufacturers replace helmets damaged or destroyed by accident free of charge, provided an accident can be proven (e.g. police report). You should also pay attention to the manufacturer's instructions on when to replace the helmet.

Mechanical side effects

A cyclist's helmet increases the mass of the head by around 5%, the moment of inertia around the base of the spine by around 10%, depending on the mass of the helmet and the mass of the head. This increases the forces resulting from acceleration when the head is freely movable.

The helmet enlarges the effective head diameter by about 20%, so that the leverage of external forces. Particularly in the case of a side impact with a horizontal velocity component, the moments acting on the cervical spine attachment are significantly greater. Both can contribute to injuries or lead to more serious consequences of an accident.

Use

Since the ability to absorb energy is limited, a bicycle helmet can only offer limited protection. The amount of benefit is controversial.

From a study of over 4,000 injured cyclists in accidents in the city and district of Hanover between 1985 and 2003, which resulted in clinically treated injuries, the author concluded that "more consistent helmet use and the expansion of cycle paths [...] are sensible preventive measures" . Of the 4,264 injured, 78 or 1.7% had worn a helmet. 55% of all injured “used bicycle lanes before the accident. 16.8% of the accidents occurred directly on cycle paths ”. 64.3% of all accidents occurred at intersections, junctions or property entrances. Injuries to the legs were most common (62%), mostly as a result of direct impact from a motor vehicle; In 46% of the cases there were injuries to the arms and in 21% of the thorax. In 48% of all cases there were injuries to the head, of which 68%, i.e. 32% of all accidents, were injuries “above the 'ear level'”, “ie in the protection area of ​​the helmet”. The severity of these injuries to the head between the abrasion of the skin and the fracture of the base of the skull was not given, nor was the distribution of the injuries to the face and the actual skull, nor the combinations of injuries to the various parts of the body.

After evaluating 16 studies, the British Ministry of Transport came to the conclusion that all studies demonstrate a protective effect, but the statements about the extent of the protective effect vary. Various studies, the results of which have not gone unchallenged, claim that wearing a bicycle helmet reduces head injuries by up to 88 percent and also lowers the death rate in bicycle accidents. In this respect it is concluded that bicycle helmets represent effective and sensible protection. Consequently, the use of helmets is a sensible and important measure to reduce head injuries.

Other studies found that head injuries accounted for only about 5 to 10% of all injuries to cyclists. The share of injuries to cyclists in all head injuries, at 1%, is well below the share of car occupants (48%) and motorcyclists (13%).

Most of these studies are, however, exploratory studies, not randomized studies, as required by evidence-based medicine . Their informative value is therefore limited by various statistical problems (see e.g. cum hoc ergo propter hoc ). There are no studies on the question of whether "frequent riders", i.e. people who regularly cover long distances by bike, wear a helmet more than average, nor on the question of whether "frequent riders" are more foresighted and less risky based on their experience driving, which would put the usefulness of the helmet back into perspective. It is also unclear how many injuries that were avoided through the use of a helmet (falling over from a standing position, falling at low speed on slippery roads) did not even get into the statistics because there was no doctor's visit or hospitalization. There are no further studies on the question (regardless of the question of whether the bicycle helmet helps prevent life-threatening injuries), how many days off work, e.g. B. can be avoided by a slight concussion, so whether the bicycle helmet has an economically measurable benefit.

There are also studies that do not show any significant protective effect of bicycle helmets. A Canadian study came to the conclusion that the positive effects of compulsory helmets could hardly be determined and appear to be minimal. However, in connection with the study, it is noted that bicycles are primarily used as sports equipment in Canada.

Finally, there are also assumptions that in certain types of accidents, helmets actually increase the risk of injury, especially due to increased rotational forces. One study found that drivers leave less distance when overtaking cyclists if the cyclist is wearing a helmet, which increases the risk of accidents.

Standards and test methods

Bicycle helmets that come onto the market in the European Union and Switzerland must pass a test in accordance with EN  1078. Probes with masses between 3.1 and 6.1 kilograms must:

  • falling from a height of around 1.5 meters onto a level, the impact speed is 19.5 km / h;
  • Falling centrally from a height of around 1.1 meters onto a roof-shaped target, the impact speed is 16.5 km / h.

The drop target is made of steel. The sensor built into the probe must never measure more than 250 g acceleration. The test head must be manufactured in accordance with DIN EN 960.

distribution

A survey by the Swiss Advice Center for Accident Prevention (bfu) showed that between 2005 and 2011 around 40% of Swiss cyclists wore a helmet. The wearing rate was only 15% in 1998 and rose steadily until 2005. The wearing rate for young cyclists (15-29 years) and in French-speaking Switzerland is below average .

Bicycle helmet compulsory

Wearing a bicycle helmet is often recommended for cycling , for example on the occasion of the 47th German Traffic Court Conference or by the authors of the study “Dangers and risk factors when cycling in Austria”, which the ETH (Swiss Federal Institute of Technology Zurich) and the University of St. Gallen im Carry out an order from Basler Versicherung . However, both motorists and pedestrians are more likely than cyclists to suffer a head injury in the event of an accident, without there being any similar recommendations.

Therefore, among other things, a helmet requirement for cycling in road traffic is controversial.

The proportion of head injuries in cycling accidents is around five to ten percent. Proponents of mandatory helmets are convinced that wearing helmets protects against head injuries in accidents. It is therefore often prescribed by cycling organizers .

A statutory helmet requirement, however, statistically increases the individual risk of accidents for the remaining cyclists, primarily due to the decline in bicycle use, since serious bicycle accidents are usually caused by mistakes by drivers and fewer bicycles are more often overlooked in the streets (“Safety in Numbers”). It also has a noticeably negative effect on a country's cycling culture .

The study for Austria mentioned at the beginning of the paragraph and published by the Baloise Group also came to the conclusion:

“For the reasons mentioned above, the experts reject the general helmet requirement for cyclists. Compulsory helmets would even be counter-productive, as this leads to a decrease in cycling, as international studies have shown. The remaining cyclists with helmets would then be more exposed to danger, as there are few cyclists who tend to overlook cyclists - the number of accidents would increase per cyclist. [...] In general, the expert explains that the helmet contributes to safety, but is not a panacea, as the helmet alone does not make cycling safer. "

Furthermore, even a small decrease in bicycle use leads to a loss of health benefits through physical exercise, which overcompensates for a possible reduction in the risk of injury and, in total, leads to poorer health in the population.

In addition to having a protective effect, a helmet can also present various dangers:

  • Riskier driving behavior due to the feeling of security created by the helmet ( risk compensation ).
  • Riskier driving behavior of other road users, in particular shorter distances when overtaking; however, further analysis of the same data calls this theory into question.
  • Depending on the course of the accident, a higher risk of injury; For example, it is discussed whether increased rotational accelerations of the head caused by a helmet increase the risk of brain damage. The face and especially the jaw are not covered by a bicycle helmet and the risk of a jaw injury could be increased.

In the opinion of bicycle helmet critics, these negative effects speak against the introduction of mandatory helmet use in bicycle traffic.

Situation in individual countries

Worldwide spread of mandatory bicycle helmets
  • General helmet requirement
  • Helmet compulsory without a fine
  • Partial helmet compulsory
  • For kids only
  • Partly local regulations
  • No helmet requirement
  • Albania

    In Albania, helmets are compulsory for all cyclists.

    Australia

    In Australia , a helmet requirement was introduced in the state of Victoria in July 1990 and extended to the whole country in July 1992. After the introduction of compulsory helmets, the use of bicycles fell by around 20 to 40 percent.

    Germany

    In Germany there are no legal regulations for wearing a cycling helmet in traffic. Contributory negligence for head injuries as a consequence of an accident due to the lack of a bicycle helmet is assessed differently in the case law for cyclists who are on the road for sporting purposes, whereby the judgments that found contributory negligence are sometimes legally controversial. Cyclists who did not use the bicycle for sporting reasons were not assigned contributory negligence due to a missing helmet in the case law of the higher regional courts and the Federal Court of Justice. In February 2014, the Higher Regional Court of Celle ruled that helmets were only compulsory “if you drive at risk”. A controversial ruling by the Schleswig-Holstein Higher Regional Court from June 2013, which attributed 20 percent contributory negligence to the head injuries caused by a properly behaving cyclist, was overturned by the Federal Court of Justice on June 17, 2014.

    The introduction of mandatory helmets for cyclists has been under discussion in Germany since the 1970s. It is discussed whether the assumed higher protection of road users from head injuries in accidents justifies an encroachment on the freedom of choice to wear a helmet. If the introduction of compulsory helmets for cyclists, it is feared that - as in some states in Australia - the number of cyclists would decrease, which would increase the risk for the remaining cyclists.

    In 2007 there were a petition to the Bundestag that a helmet law for cyclists with a reference to the poor state of cycle paths called and "cheap bicycle". This was in 2008 by the Bundestag u. a. rejected due to the threat of “overregulation”. In addition, the committee came to the conclusion: "Many cyclists [...] will no longer use the bike as before, but leave it there." The coalition agreement for the years 2013 to 2017 does not contain any plans to make helmets compulsory.

    Finland

    According to Section 90 of the Finnish Road Traffic Act, cyclists and bicycle passengers should generally wear a suitable helmet when driving. This recommendation, which has been in force since January 1, 2003, is not subject to any fine or financial penalty.

    Canada

    In Canada , helmet requirements were introduced in six of the ten provinces between 1994 and 2003.

    Iceland

    In Iceland, helmets were made compulsory for people under the age of 15 in 1999.

    Austria

    With effect from May 31, 2011, § 68 (new) Paragraph 6 of the Austrian Road Traffic Act introduced compulsory cycling helmets for children under 12 years of age. This applies when the child rides a bicycle himself, when it is carried on a bike and when it is carried in a bicycle trailer . The person accompanying or transporting the child is responsible for ensuring that the child is obliged to wear a helmet. In the absence of a criminal provision, however, a violation of the provision remains without sanction . In addition, this provision expressly excludes contributory negligence in accordance with Section 1304 of the Austrian Civil Code in the event of an accident, and indirectly also a reduction in compensation in the event of an objection of contributory negligence.

    Sweden

    In Sweden , helmets have been compulsory for cyclists under 15 years of age since July 1, 2005. The proportion of children under 10 years of age wearing helmets in residential areas increased from 35% to 70% between 2005 and 2012, at the same time the helmet wearing rate for children between 6 and 15 years of age who drive to school rose from 37% to 59%. The total number of seriously injured cyclists (hospitalization) remained about the same for the same period (~ 3,000 p. A.), The number of cyclists killed fell from 35 to 23. For adults, the helmet wearing rate remained stable at 27% between 2007 and 2012, during this time the total number of cyclists killed fell from 33 to 23 (compared to 1998 with 18% helmet wearing rate: 58).

    Switzerland

    In Switzerland there are no legal regulations for wearing a cycling helmet in traffic. In November 2008, the Swiss has Bundesrat the bill Via sicura in the consultation given. This law would empower the government to introduce wear and tear in Switzerland at any time and without a parliamentary resolution. In June 2012, Parliament rejected this security measure. The parliamentarians unanimously called for the wearing of helmets to be promoted, including with prevention campaigns.

    Slovakia

    In Slovakia , helmets are generally compulsory for cyclists under 15 years of age.

    Spain

    In Spain , a helmet is mandatory for cyclists outside built-up areas (§118 RGC). Helmets are not required for long inclines, extreme heat and medical indications. Since May 1, 2014, helmets have been compulsory for everyone up to the age of 16.

    Czech Republic

    In the Czech Republic , helmets have been compulsory for cyclists under the age of 18 since July 1, 2005.

    Outside of Europe

    Examples of compulsory states outside of Europe include New Zealand (nationwide), Australia (in some areas), and some states in the United States . In the United States, helmet requirements are regulated at the level of the individual states, and sometimes also in individual counties. As of 2011, helmets were not compulsory in 28 states, and helmets were compulsory for children and / or adolescents in 22 states.

    Airbag helmets

    The Hövding is the world's first airbag for cyclists. The U. a. The protection system received as an “airbag helmet” or “invisible helmet” is worn as a collar around the neck. A fall of the wearer is to be detected under sensor control and the airbag inflated within 0.1 seconds, which is supposed to protect the head as a kind of air-filled bicycle helmet in the event of an impact. Various external studies (including those from Stanford University ) have shown that Hövding can provide up to eight times better protection than classic bicycle helmets.

    literature

    • Andersson, Larsson, Sandberg: Chin strap forces in bicycle helmets. Swedish National Testing and Research Institute, SP Report, 1993.
    • Kippa, headscarf, bicycle helmet. In: FACTS. No. 27/2005, pp. 26-28.
    • DIN EN 1078, helmets for cyclists and users of skateboards and roller skates. German version EN 1078: 2012 + A1: 2012. Beuth Verlag, Berlin 2013.

    Web links

    Commons : Bicycle Helmet  - Collection of pictures, videos and audio files
    Wiktionary: Bicycle helmet  - explanations of meanings, word origins, synonyms, translations

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