6 ms·

It's not the polystyrene which cracks, but the plastic shell holding it in place. The separation will happen after the compression force is removed, because the

• ndsipa_pomu 4y ago
  The pictures that I've seen of the various "saved my life" destroyed helmets have the polystyrene split apart - it's usually quite easy to split polystyrene if the force is applied the right (wrong) way. I don't like the concept of requiring PPE for a relatively safe activity as cycling as it makes cycling seem like a far more risky activity than it is and there's also the problem of "helmet hair" which can dissuade commuters. It's telling that countries where bike helmets were mandated had a sharp downturn in the numbers of cyclists.
  • 323 4y ago
    Cycling is risky. I've stopped cycling on roads with cars because I realized it's just a matter of time until I get in a serious accident. https://www.washingtonpost.com/express/wp/2016/05/12/how-safe-is-bike-commuting-perhaps-less-than-you-think/ https://www.washingtonpost.com/express/wp/2016/05/12/how-saf... I'm with you on the mandatory helmet issue, I don't like it either, but mostly because I don't like needlessly restricting ones freedoms, if you want to risk your life, that's fine with me as long as you don't risk others lives too.
    • bluejekyll 4y ago
      Cycling is only risky due to the shared infrastructure with cars. The thing that raises the risk is cars. We should all be demanding that our streets are made safe for all users. We already have sidewalks in many places for this reason, we just need to extend similar safe infrastructure to bicycles and other road users too. Just throwing your hands up and not asking for change is a sure way to not improve things.
      • op00to 4y ago
        No one has ever been injured cycling on a trail! It’s amazing how the laws of physics no longer apply once you stop sharing infrastructure with motor vehicles. More seriously, you can easily hit a rock or something and go over the handlebars on a bike path.
        • u801e 4y ago
          Bike paths also tend to have more surface hazards because they're not designed following stringent standards that designers of roads have to follow.
        • confidantlake 4y ago
          It isn't a binary thing but a rate.
        • seoaeu 4y ago
          There’s worlds of difference between crashing your bike versus being hit by a car while riding your bike. Yeah, it’ll hurt either way, but the former is substantially less likely to be fatal
        • kevinmgranger 4y ago
          A human being's weight hitting the ground at 30 mph (already a generously high figure) is far less serious than a multi-ton vehicle hitting them at 30 mph (already a generously low figure). So, yes, physics.
      • stevejb 4y ago
        I used to live next to a popular bike trail, that had 0 sharing with cars. Not a road within 50 meters. There were plenty of injuries. Bike vs bike, bike vs pedestrian, bike vs stationary object, distracted cyclist injures themselves. Etc. If you're going 30 km/hr in thin lycra, you can certainly injure yourself with no help from anyone or anything else.
        • bluejekyll 4y ago
          This is a common issue in this discussion. People using bikes for sport is a different category for cyclist than an urban and/or casual rider. When cycling for sport you should always wear a helmet.
    • grey_earthling 4y ago
      Sounds more like it's the cars that are risky, not the cycling.
      • threeseed 4y ago
        Well done. You've figured out that cars are in fact incredibly dangerous objects. Now you just need to figure out how to cycle from A to B that doesn't interact with them.
  • pengaru 4y ago
    Cycling has a pretty high probability of crashing/falling, and in such an event there's a good chance your face/head will impact something. Not that I'm in favor of requiring wearing any safety gear, I'm totally in favor of weeding out morons from the gene pool. But to act like helmets aren't a good idea for cyclists is asinine. Personally I try always rock a full-face MTB helmet when I'm cycling.
    • ndsipa_pomu 4y ago
      The full-face helmets provide much better protection, but they have the trade-offs of being more uncomfortable and hotter. I'm not convinced that cycling is especially dangerous and my experience is that I've inevitably put my hands out when falling, so I think that gloves should be the first part of PPE recommended for cyclists. Luckily, I've never hit my helmet/head when coming off so I've found that a bike helmet is most useful for stopping low branches etc from hitting me. I'd recommend cycling/protective glasses too - very good for protecting against insects hitting your eyes. I find it interesting that people seem to have a skewed attitude towards head protection and cycling. If head protection is that important, then why are helmets not recommended for car passengers, people showering, changing a lightbulb etc.?
      • pengaru 4y ago
        > then why are helmets not recommended for car passengers, people showering, changing a lightbulb etc Strawman much? car passengers: airbags and seatbelts are in direct conflict with and superior to helmets. people showering and changing lightbulbs are not traveling at speeds exceeding a walking pace in an orientation predisposing them for a head/facial impact for hours at a time. The full-face helmet I wear is heavily vented like any other bicycling helmet, there is practically no worse comfort than any other cycling helmet worth wearing. And considering how much I appreciate my teeth and not potentially needing to drink hamburgers through a straw while my broken jaw heals due to a cycling mishap, even if it were less comfortable I'm totally on board. I've written this up with details in previous comments on this subject, but I have multiple friends/friends' family members who have suffered substantial facial/dental injuries in seemingly totally benign cycling activities gone awry. All of them would likely have been non-events had they been wearing a full-face MTB helmet.
  • ComputerGuru 4y ago
    Cycling in a vacuum is safe-ish and not a particularly risky affair. Cycling on a shared road with automobiles going eight times your speed and weighing some 250 times your bipedal vehicle’s weight is not so safe.
    • ndsipa_pomu 4y ago
      I'd recommend reducing your tyre pressure and definitely remember some oxygen.
    • u801e 4y ago
      Differences in speed and mass are largely irrelevant if collisions don't occur. You can minimize the risk of a collision by following the rules of movement on the road (right of way and positioning) and anticipate if someone isn't following those rules and take appropriate action to avoid a collision before it's imminent. If passenger cars, large trucks and buses. and motorcycles can share the road, so can pedalcyclists.
      • seoaeu 4y ago
        > If passenger cars, large trucks and buses. and motorcycles can share the road, so can pedalcyclists. Separated bike infrastructure empirically reduces cyclist fatalities. And it isn’t hard to guess why.
        • u801e 4y ago
          The vast majority of collisions cyclists are involved in happen at intersections (incluing mid block drivways and alleys). Very few collision involve hit from behind. Cycling infrastructure that places cyclists in the pedestrian position when crossing an intersection exacerbates the risk of getting into a collision when crossing the intersection because motorists aren't really looking to see someone moving at cyclist speed as they're exiting the intersection. The other problem is that cyclists are hidden from view by parked cars until a short time before entering the intersection. This makes it difficult for both the cyclist and motorist to see each other until it's too late to avoid a collision. If you're not riding where motorists are looking, you're far more likely to end up in a collision, fatal or not[1] [1] https://www.youtube.com/watch?v=4k6-AI_X1qE https://www.youtube.com/watch?v=4k6-AI_X1qE
  • vkou 4y ago
    Cycling on roadways is not a relatively safe activity. I don't know a single cyclist commuter that has not been involved in a car crash - and I'm in my early 30s.
    • QuarterReptile 4y ago
      I admittedly only commuted by bike for 3 years, 2018-2020, but I was never involved in a crash. I ride in some ways contrary to common advice, but that may contribute.
    • jessaustin 4y ago
      Hi, 'vkou. Nice to meet you. I once got doored, but I didn't crash as a result. Also the car that doored me was parked at the time.
  • rhinoceraptor 4y ago
    Also, the average person likely drives much more than rides a bicycle, so they're much more likely to be injured in a car accident. But no one would suggest mandatory helmet use for drivers, even though that would likely prevent many times more deaths and injuries than mandatory bicycle helmets.
    • seunosewa 4y ago
      Seatbelts and airbags provide very good protection for drivers' heads. If cars didn't have those, drivers would need helmets.
      • u801e 4y ago
        Many motorists do suffer head injuries in crashes.
    • michaelmrose 4y ago
      Can you provide some evidence that helmets provide additional benefits when used in combination with airbags and seatbelts? Specifically actual testing. You would probably want to look at auto racing. My gut feeling is that even a slight decrease in visibility in a car wherein visibility is already limited would make a collision more likely and airbags would already provide substantial cushioning for your head so long as the seatbelt keeps the driver in the car. I think helmets in a car would be a net loss.
• dharmab 4y ago
  Motorcycle helmets are typically also polystyrene, although with multiple densities for handling both light and heavy impacts. Motorcycle helmets also have degrees of protection, from the useless DOT standard to the less bad Snell standards to the quite good ECE and FIM standards.
• KennyBlanken 4y ago
  > It's not the polystyrene which cracks, but the plastic shell holding it in place. The separation will happen after the compression force is removed, because the compression will keep the split parts close together. Meaning that the helmet falls apart after it's done the job. Nope. As a cyclist, I've seen numerous people in social media groups, friends, etc post pictures of their helmets that "saved their lives." Every single time, it's cracked to pieces, with no visible denting to the polystyrene foam. Deformation of that foam is how a helmet absorbs impact force, and cracking apart is a failure of the helmet. Bike helmets in the US are required to pass one test - a weight being dropped directly on top of the helmet that simulates a detached adult male head falling onto the ground from about the height of an average adult male. The test makes absolutely no sense, because the whole thing is a sham.