The takeaway from all this is that a bicycle helmet is more or less a bicycle helmet. In most locations, several hundred adults were tallied. In this and all graphs, data for kids was only included when I tallied 20 or more in a given location. Also note usage by men and women is close, probably within the margin of error, but I recall there was a much more significant difference between men and women when I did this 10 years ago and lost the data.
I originally attempted to tally data for teenagers separately but was unable to do so because of how few teenagers apparently ride bicycles, and it was difficult to classify riders into three classes instead of two.
Now the Minneapolis Parkways in comparison to other areas. I only note that areas where bicycles are transportation have much lower bicycle helmet use than areas for recreation. Different city neighborhoods probably have vastly different usage rates and thus of all my data; lumping the data for the city of Minneapolis together, even excluding recreational trails, downtown, and the U, probably made it meaningless.
Also I noticed bicycle helmet use seems essentially nonexistent in small town Minnesota. Helmets are also recommended for inline skating. I did not break this out by location but most inline skating is done on recreations trails. Now for the elephant in the room: We now have some idea how many Minnesotans use bicycle helmets, but should it be mandatory, or should they do it voluntarily. My take on the great bicycle helmet debate will be coming up next so please refrain comments on that line until then.
I really enjoyed this read. That was nice! I look forward to your next post. I once was rollerblading on a rereational path and collided with a bicycist. I was able to dive to the grass at the last minute so I was generally ok.
The cyclist was not wearing a helmet and slammed the back of his head on the asphalt. A few very quick thoughts from memory so may need some corrections. Australia mandated helmet use beginning in Bicycle fatalities decreased, but by much less than the rate of bicycling, indicating that fatalities and presumably injuries increased per mile travelled.
The rate of helmet wearing appears to have zero effect on TBI. There is a supposition, likely at least somewhat accurate, of safety in numbers. The more people riding bicycles the more aware and careful drivers will be and thus the fewer crashes, injuries and fatalities per mile ridden. In just a year or so the junk that could not meet the ANSI standard was swept from the market, in some cases by lawsuits.
Virtually all of them had a simple strap design shaped like a Y on each side. For buckles, most had d-rings or plastic buckles made by Fastex. In the early 's the next big step in bicycle helmet design occurred when Bell introduced their "L'il Bell Shell" infant-toddler design. To make the helmet lighter, Bell dropped the outer shell, producing a thick all-EPS helmet that was highly protective.
The design was actually an adaptation of a helmet Bell had produced for pediatricians to protect child heads after surgery. Bell limited the idea to toddler helmets in the belief that adult helmets would always require a hard shell. In a designer named Jim Gentes designed an adult bike helmet with some vents and no shell, and formed Giro Sport Design to market the concept.
The lighter weight was an instant hit, and Giro began selling large quantities of the helmets to racers and others who could afford the high price. Giro used an outer cover of thin lycra cloth. The cover was hand sewn in the US and was one of the major costs of producing the helmet. The all-EPS helmets that followed soon distinguished themselves as protective helmets that had an unfortunate tendency to catastrophic failure in the first blow.
Their Mirage model had a nylon mesh inserted in the foam, clearly visible in the vents. The mesh is visible in the vents in the second photo above. It worked well, and has been followed by thousands of other designs using internal reinforcing to hold the foam together. The early ones, including the Pro Tec, still had cloth covers and no outer shell.
The next big design step appeared about with the reintroduction of a shell to cover the EPS, this time in PET milk jug plastic and other thin, tough plastics. The shell helped to hold the foam together in an impact and lowered the sliding resistance of the helmet to make it skid more easily on pavement, both important safety features.
In just a few years this thin shell design took over the market, replacing both the remaining hard shells and the cloth-covered EPS-only designs. The shell was produced separately from the interior foam, and then glued or taped on. Another innovation in the early 's was molding the foam in the thin shell, by placing the shell in the mold first, then expanding the EPS bead to fill it.
The heat of the process then requires a higher grade of shell than PET, usually a polycarbonate, since PET will melt at the temperatures in the mold. The technique fills the shell completely, with no gaps between the foam and shell unless there are quality control problems. That permitted the designer to produce a more protective helmet with the same thickness.
Designers quickly found that the same technique permitted them to thin the helmet down for more appealing styling and to open up more vents. In the years since some manufacturers have continued making the hard shell, mostly in ABS plastic.
Most of their models are for skate-style helmets only, where the style endures. At about the same time as thin shells, manufacturers added a supplemental stabilizer in the rear of many models in the form of a plastic patch or cloth strap in the rear to hook below the bulge in most riders' heads the occipital bone and hold the helmet on better.
Many innovations in these stabilizer designs have followed. The most efficient shape for a helmet in a crash resembles a bowling ball.
Round, smooth surfaces slide well and "scrub off" energy from a crash, while avoiding any tendency for the helmet to snag and jerk the rider's neck. This has been demonstrated in lab tests. But designers began flogging "aerodynamic" designs in the late 's as the aero craze peaked. Greg LeMond wore one in a famous time trial where he came from behind to win the Tour de France. Bicycle helmet shapes have become elongated ever since, basically as a fashion trend, since the aero quality of the helmet has no real effect at the speeds most riders travel.
An unfortunate trend in shapes became evident in the late 's as designers began producing helmets with ridges, rear projections and squared-off lines to give them a more stylish appearance. We have ranted against the trend, but without much effect, and have been unable to get provisions in any standard requiring low sliding resistance. We could only hope the fashion will reverse as fashions always do, and lead us back to smoother designs. Finally in there were signs of at least a few rounder, smoother designs produced for the "commuter helmet" niche in the market.
Bell introduced the Metro, followed quickly by a number of others. The Metro was an intentionally clunky design, but SixSixOne found a design in China shortly thereafter and brought the helmet on the right below, the Allride, to the US market. Weak marketing doomed it to low sales, and the company dropped it from their line after But the original producer brought it back for as the Vcan VCK37 on left below.
The manufacturer advertises it as a more aerodynamic design based on automotive research. Track racers in the UK were early adopters and their demand alone led to backorders for the helmet. It is not clear why the aerodynamic claim led buyers to reject all of the aero research of manufacturers of the elongated designs. The extreme of the elongated aerodynamic style is the chrono helmet developed in the 's for Olympic time trials.
This one has a rounded front and usually has a very long tail that rests on the riders back when in the tuck position used by time trial riders. Vents are minimal or non-existent. Early models had only a shell without impact protection, but in Louis Garneau introduced one that met the requirements of the US CPSC standard, and various manufacturers soon began making them to the European CEN standard.
We have a page up on current chrono helmets. Another major helmet shape that crept into bicycle helmets is the "skate-shaped" helmet. Originally developed for skateboarders by Pro-Tec, the style has lower rear coverage, small round vents in the front and even smaller round vents in a circle on top. The skate style helmet is almost always a hard shell with ABS plastic. Although originally using a squishy rebounding foam that provided the multi-impact performance needed for aggessive skateboarding, the helmets evolved into bicycle helmets because the squishy foam would not perform in harder impacts called out by bicycle helmet standards.
After when the CPSC standard came into effect, big-box retailers were not willing to put a helmet on the floor that could be bought as a bike helmet but did not meet the CPSC standard. As a result, most skateboarders now are buying single-crash bike helmets with crushable EPS foam inside. A few manufacturers are making helmets with EPP foam or other foam that can be certified to both the ASTM skateboard helmet standard and the bicycle helmet standard.
Liners Until the 21st century, bicycle helmet liners were all crushable foams. In the late 80's or early 90's came the introduction of new foam types to replace the simple EPS picnic cooler foam that dates from the 's. It is extensively used in the automobile industry. EPP has the desirable characteristic of slow return to its original shape after an impact, and is therefore well suited to multi-impact helmets.
It is generally considered to have slightly more rebound on initial impact than EPS, and a little less impact attenuation for a given thickness.
Although Aria Sonics had an EPP helmet for five years or more, the design was never appreciated by consumers, and its marketing was inadequate to establish its advantages. A Canadian company called Headstart introduced EPP designs in the mid's, but the helmets were not well finished and did not have the quality appearance that was required to sell in the U.
Although GE had not originally designed its combination foam and resin product for bicycle helmets, it was appreciated for its resistance to catastrophic failure, permitting manufacturers to open up larger vents and thin out liners in some places. This is a slightly heavier foam with exceptionally small and uniform cells. It skins over in the mold, producing a shell-like cover on the lower section below the regular plastic shell. EPU can be inmolded or the shell can be applied afterwards. It has almost no rebound and performs well in lab tests.
Taiwanese manufacturers are the main users of EPU, and helmets made of it are among those on the Snell B certification list, indicating that they perform well indeed. Few helmets are designed to offer protection better than that specified by the standards.
There is no mandatory, third-party testing of helmets, and independent surveys have shown that many of the helmets on sale do not meet the standards to which they are accredited. Very few meet the more demanding standards. All standards prescribe tests using a flat anvil though with greatly differing impact energies but few include a test involving a hemispherical anvil, which is often closer to real-life crash conditions. No standard specifies tests involving rotational impacts.
This appears to be an acknowledgement that the foam in most helmets is too rigid to crush as intended. Injuries to the head may be divided into direct, or focal, injuries and rotational, or diffuse, injuries. Direct injuries occur as a result of linear acceleration of the skull by impact with another object, and typically lead to cuts, lacerations and concussion.
Direct injuries, though sometimes painful, usually have minimal long-term effect. Rotational injuries, on the other hand, do not necessarily involve direct contact with the head but result in the brain moving relative to the skull as a result of angular or rotational acceleration, which leads to diffuse axonal injury DAI and subdural haematoma SDH. These are the most common ways that road crashes cause death or chronic intellectual disablement.
Cycle helmets may produce benefit by reducing and spreading the forces that lead to direct injuries. However, they are not designed to mitigate rotational injuries, and research has not shown them to be effective in doing so. To the contrary, some researchers have expressed concern that cycle helmets might make some injuries worse by converting direct forces into rotational ones. These injuries will normally form a very small proportion of the injuries suffered by cyclists, but they are likely to form a large proportion of the injuries with serious long-term consequences.
In this way cycle helmets may be harmful in a crash, but this harm may not be detected by small-scale research studies. The active promotion of helmet use by cyclists is a fiercely controversial and often emotional subject, with views put forward with great conviction both for helmets and sceptical of their value very few people argue against the voluntary use of cycle helmets per se.
Controversy is particularly acute with regard to mandatory helmet laws. The arguments in favour of helmet use are invariably based upon the premise that in the event of a fall, a helmet might substantially reduce the incidence and severity of head injuries. A relatively small number of medical research papers are cited in support of this premise, most based on case-control studies. However, the methodology and findings of this paper have been widely criticised and there is no real-world evidence to support its predictions.
Proponents of helmet use include people from within the medical and road safety professions and also people who believe that a helmet has already saved them, or a relative or acquaintance, from serious injury. Helmet-sceptic arguments are more varied. Originally based largely on issues associated with personal liberty, the balance of helmet-sceptic arguments changed during the s as the health benefits of cycling became more acknowledged and as independent research started to be undertaken into the outcomes of rising helmet use and, in particular, the effects of cycle helmet laws.
Helmet sceptics include cycling organisations especially in Europe where some have undertaken their own research , public health doctors and other professionals concerned with cycling safety, encouraging cycle use and helmet analysis.
Most cycle users are also not convinced of the net benefits of helmet wearing as in most places fewer than a third of people choose to wear one when use is voluntary.
In recent years many individuals and cycling organisations have swung from pro-helmet to helmet-sceptic as a result of experience with helmet laws and the growing breadth of evidence. Most published medical research that has studied the effectiveness of cycle helmets has been based on case-control studies, where groups of cyclists, with and without helmets, have been compared.
This research has led to predictions of very large reductions in head injury through the use of cycle helmets — Table 1 shows the predictions of some of the most frequently cited papers. Three meta-analyses of case-control studies have also found strongly in favour of helmet effectiveness. Although a considerable number of papers have been published in the medical journals expressing support for helmet use, very few could be described as primary research into helmet effectiveness.
The majority are either dependent upon the results of earlier research, or are concerned with secondary matters such as the promotion of helmet use. As early as Rodgers studied 8 million cases of injury or death to cyclists in the USA over 15 years - the largest survey of its kind ever undertaken. He concluded that there was no evidence that hard shell helmets had reduced head injury or fatality rates.
Indeed, he found that helmeted riders were more likely to be killed. A decade later, Kunich analysed cyclist and pedestrian fatalities in the USA and concluded that there was no evidence that cycle helmets were effective in reducing deaths. Spaite found that bare-headed cyclists more often had severe injuries. However, this was true even when cyclists without major head injuries were analysed as a group. The implication being that people who do not use helmets tend to be in higher impact collisions than helmet users, since injuries are more severe to all parts of the body.
There was no clear evidence that cycle use had increased. An analysis of cyclist and pedestrian fatalities in Canada from to showed that trends for both modes were similar and the number of deaths fell in both cases. In , a wide-ranging international review of the literature for the UK Department for Transport when both pro-helmet and helmet-sceptic interests had the opportunity to contribute towards the evidence considered concluded that there was no reliable evidence that cycle helmets have resulted in a lower risk of head injury for cyclists.
The UK courts have not to date determined that wearing a helmet would have made any material difference in the cases of serious or fatal injury that they have considered. In these circumstances, a detailed analysis of crash causation and the individual crash circumstances is carried out.
So far as can be determined, nowhere in the world has an increase in helmet use resulted in a fall in head or brain injuries relative to cycle use.
Helmet laws in Australia provided excellent data sets with which to test the effectiveness of cycle helmets because a principal effect of the laws was to increase substantially over a short period of time the proportion of cyclists wearing helmets. This enabled a comparison of a very large number of individuals not wearing and then wearing helmets, eliminating most of the other variables present when comparing different people or dissimilar riding conditions.
At first, reports suggested that legislation had achieved its aim of reducing head injuries. But the researchers did not take into account the very large decline in cycle use brought about by the laws.
The main effect of the law was to discourage cycling rather than to encourage cyclists to wear helmets. Furthermore, the proportional reduction in head injuries for cyclists was very similar to that for unhelmeted pedestrians over the same period. In , the Australian Road Accident Prevention Research Unit compared head injury rates of cyclists, pedestrians and other road users. All followed similar declining trends, and the data see graph above suggests that there was no enduring benefit at all for cyclists.
The report concluded that the law had not been cost-effective. New Zealand followed Australia with a mandatory helmet law. This law was also found not to have been cost effective and the head injury rate did not decrease more than for the population at large.
In Canada, too, in those provinces where helmet laws have been enforced, no benefit is apparent. In British Columbia and Nova Scotia there was no change in the proportion of cyclists suffering head injuries post-law, although cycle use fell markedly. Most helmet laws that have been enacted have not been much enforced. This is especially true of child helmet laws in many states of the USA. These laws have less impact on either cycle use or helmet use than enforced laws. There is no credible evidence that they have resulted in a lower risk of head injury.
On the other hand, unenforced laws can erode public respect for the rule of law generally, and traffic laws in particular, especially amongst the young people at whom most helmet laws are targeted. All data sources are subject to error and data collection practices vary widely. But simple data errors are unlikely to account for the large disparities between prediction and the real-world.
Many of the studies urging helmet use rely on gross extrapolation. In subsequent evidence to a parliamentary committee, Dr Dorsch heavily qualified how the results should be interpreted but citations of her work do not usually mention this. Thompson et al. Helmet campaigners invariably focus on the latter estimate although the statistical base is weak. Using the same data, a comparison of helmet wearing rates of the cyclists who fell off their bikes with a control group who did not fall leads to a totally different conclusion: that helmet wearers have the same number of head injuries as non-wearers, but are 7 times more likely to fall off their bikes.
Moreover, data presented in that paper, such as the percentages of bicycles damaged beyond repair and the involvement of motor vehicles, make it clear that the head-injured cases had been in much more severe crashes than the two control groups.
The comparisons were thus not reliable. To reach their conclusions, helmet campaigners often assume that helmets are equally effective at preventing fatalities and very serious brain injuries as wounds and minor concussions. The much more modest results from an Australian hospital admission study McDermott that found no significant reduction in head injuries for adult cyclists, are hardly ever mentioned.
Most of the frequently cited pro-helmet research has been criticised for fundamental methodological shortcomings, particularly with regard to case-control techniques.
0コメント