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>> Helmets are pretty misunderstood. They don't offer much in the way of protection in a serious accident > Have you got a source for that claim? The CPSC (Co

by u801e 9y ago

>> Helmets are pretty misunderstood. They don't offer much in the way of protection in a serious accident > Have you got a source for that claim? The CPSC (Consumer Products Safety Commission) impact testing standards for bicycle helmets only require that the pass tests like a guided free fall on a weighted headform from a height of about 6.5 feet. That's the equivalent of falling over from a trackstand, for example. If you're going at speed or are hit by a car, the forces the helmet will experience will far exceed the force generated by the impact tests as specified above.

dahart 9y ago
That's true. But the numbers I cited above came from actual collisions, not from CPSC testing. The actual fatality rate when cars are involved is considerably lower with a helmet, verified many times over across many studies.
stordoff 9y ago
> If you're going at speed or are hit by a car, the forces the helmet will experience will far exceed the force generated by the impact tests as specified above Does that matter? It may not be ideal, but even a helmet that only meets those requirements is going to _reduce_ the force experienced if you land on it. My dad was in a crash with a car (impacted the side of the vehicle, went over the top and landed on the other side) - his helmet was cracked into three pieces, but he was fine. I find it difficult to picture him avoiding some sort of head injury without the helmet.
- u801e 9y ago
  > It may not be ideal, but even a helmet that only meets those requirements is going to _reduce_ the force experienced if you land on it. My dad was in a crash with a car (impacted the side of the vehicle, went over the top and landed on the other side) - his helmet was cracked into three pieces, but he was fine. From [1]: >> The principal protection mechanism in a cycle helmet is the polystyrene foam, or styrofoam, that covers the head. When this receives a direct impact force, the styrofoam is intended to compress and in this way spread and reduce the force that is passed onto the skull, thus reducing linear accleration of the brain. >> However, it is common for helmets to break without the polystyrene foam compressing at all. A major helmet manufacturer collected damaged childrens' helmets for investigation over several months. According to their senior engineer, in that time they did not see any helmet showing signs of crushing on the inside (Sundahl, 1998). Helmet foam does not 'rebound' after compression to any significant extent. If the styrofoam does not compress, it cannot reduce linear acceleration of the brain. The most protection that it can give to the wearer is to prevent focal damage of the skull and prevent minor wounds to the scalp. It is not likely to prevent serious brain injury. [1] http://www.cyclehelmets.org/1209.html http://www.cyclehelmets.org/1209.html
  - dahart 9y ago
    That argument that ignores the fact that helmets did actually prevent serious brain injuries according to the meta analysis I quoted above. It's one thing to look at some cracked helmets after a crash and suggest that they might not work as expected. It's another thing entirely to use logic to try to contradict direct evidence. Evidence wins. Regardless of whether foam compresses or cracks, the outcomes of people wearing helmets is markedly better than the outcomes of people who crash with no helmet on. To suggest that the existence of cracks mean it's unlikely to prevent serious brain injury is flatly false.
askvictor 9y ago
Also, I recall some study(sorry, don't have source) looking at how a helmet interacts with the road during a fall, vs how the scalp does. It found that the helmet grips and causes more rotation of the head and neck, whereas the scalp slips (and has several levels of slippage). This suggests that helmets might cause more neck injuries as well as internal brain injuries due to the sudden momentum shift when the skull starts rotating but the brain lags behind. This is complicated stuff, and simple messages, anecdotes or one-dimension studies don't help work out the best solutions.
- dahart 9y ago
  This is the third argument in this thread that attempts to claim that the mechanisms of crashing might mean that the outcomes are worse, in response to actual data that the outcomes are, in fact, better. This argument seems unscientific. The experiment already ran, and the data shows reduced injuries for helmets. Explaining why something "suggests" it might not work makes no sense, when it did already work on a large scale. I also don't buy that helmets grip more on average. Most are coated in plastic and my scalp is coated in skin and hair. One of those grips gravel & concrete more easily, and it's not plastic. I gave a source for the quote above, and it comes from a meta analysis of multiple studies. The simple message is simple because the science showed a large and compelling result. When the statistical significance is enormous, and the results are a clear and unmistakable positive across numerous studies and a lot of scrutiny, the message gets less and less complicated. Suggesting that there's anything complicated about wildly improved outcomes seems like FUD to me.

by u801e 9y ago

dahart 9y ago

That's true. But the numbers I cited above came from actual collisions, not from CPSC testing. The actual fatality rate when cars are involved is considerably lower with a helmet, verified many times over across many studies.

stordoff 9y ago

> If you're going at speed or are hit by a car, the forces the helmet will experience will far exceed the force generated by the impact tests as specified above Does that matter? It may not be ideal, but even a helmet that only meets those requirements is going to _reduce_ the force experienced if you land on it. My dad was in a crash with a car (impacted the side of the vehicle, went over the top and landed on the other side) - his helmet was cracked into three pieces, but he was fine. I find it difficult to picture him avoiding some sort of head injury without the helmet.

u801e 9y ago
> It may not be ideal, but even a helmet that only meets those requirements is going to _reduce_ the force experienced if you land on it. My dad was in a crash with a car (impacted the side of the vehicle, went over the top and landed on the other side) - his helmet was cracked into three pieces, but he was fine. From [1]: >> The principal protection mechanism in a cycle helmet is the polystyrene foam, or styrofoam, that covers the head. When this receives a direct impact force, the styrofoam is intended to compress and in this way spread and reduce the force that is passed onto the skull, thus reducing linear accleration of the brain. >> However, it is common for helmets to break without the polystyrene foam compressing at all. A major helmet manufacturer collected damaged childrens' helmets for investigation over several months. According to their senior engineer, in that time they did not see any helmet showing signs of crushing on the inside (Sundahl, 1998). Helmet foam does not 'rebound' after compression to any significant extent. If the styrofoam does not compress, it cannot reduce linear acceleration of the brain. The most protection that it can give to the wearer is to prevent focal damage of the skull and prevent minor wounds to the scalp. It is not likely to prevent serious brain injury. [1] http://www.cyclehelmets.org/1209.html http://www.cyclehelmets.org/1209.html
- dahart 9y ago
  That argument that ignores the fact that helmets did actually prevent serious brain injuries according to the meta analysis I quoted above. It's one thing to look at some cracked helmets after a crash and suggest that they might not work as expected. It's another thing entirely to use logic to try to contradict direct evidence. Evidence wins. Regardless of whether foam compresses or cracks, the outcomes of people wearing helmets is markedly better than the outcomes of people who crash with no helmet on. To suggest that the existence of cracks mean it's unlikely to prevent serious brain injury is flatly false.

askvictor 9y ago

Also, I recall some study(sorry, don't have source) looking at how a helmet interacts with the road during a fall, vs how the scalp does. It found that the helmet grips and causes more rotation of the head and neck, whereas the scalp slips (and has several levels of slippage). This suggests that helmets might cause more neck injuries as well as internal brain injuries due to the sudden momentum shift when the skull starts rotating but the brain lags behind. This is complicated stuff, and simple messages, anecdotes or one-dimension studies don't help work out the best solutions.

dahart 9y ago
This is the third argument in this thread that attempts to claim that the mechanisms of crashing might mean that the outcomes are worse, in response to actual data that the outcomes are, in fact, better. This argument seems unscientific. The experiment already ran, and the data shows reduced injuries for helmets. Explaining why something "suggests" it might not work makes no sense, when it did already work on a large scale. I also don't buy that helmets grip more on average. Most are coated in plastic and my scalp is coated in skin and hair. One of those grips gravel & concrete more easily, and it's not plastic. I gave a source for the quote above, and it comes from a meta analysis of multiple studies. The simple message is simple because the science showed a large and compelling result. When the statistical significance is enormous, and the results are a clear and unmistakable positive across numerous studies and a lot of scrutiny, the message gets less and less complicated. Suggesting that there's anything complicated about wildly improved outcomes seems like FUD to me.