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> 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

> 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.

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.