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Helmet - Impact

Old 11-22-19, 09:38 AM
  #26  
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Originally Posted by livedarklions View Post
I defer--I know I'm talking through my helmet.
Now where would we be if we all went around admitting stuff like that?
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Old 11-22-19, 10:35 AM
  #27  
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Originally Posted by MoAlpha View Post
Now where would we be if we all went around admitting stuff like that?
Maybe in a place where people didn't expect to be taken seriously when they tell people they've never seen ride how to cross the street or ride a bike?

That's not aimed at you, btw.

I learn a lot by saying my uninformed guess is X, please tell me if and why that's wrong. Key is not freaking out when told I'm wrong, however I reserve the right to get annoyed and push back when someone accuses me of being stupid or lazy for asking the question.
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Old 11-22-19, 10:49 AM
  #28  
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Originally Posted by livedarklions View Post
Football helmets are wildly overbuilt for bicycle use. They're designed to survive literally dozens (hundreds?) of impacts per season, while bike helmets hopefully won't see any impact during their life-span. They also cost several times the price of your average bike helmet. Foam is not just weight effective, it's extremely cost-effective. Other than the fact that people associate foam with cheap and disposable items, why would you want to make bike helmets hotter, heavier and more expensive?

Virginia Tech first got into the helmet testing business on football, nowhere have they suggested that redesigning bike helmets to be built more like football helmets is ideal.

I hear ya, and I'm not advocating using football helmets, just saying that helmet designers could incorporate some of that technology in a bike helmet. People would pay more if they were better and reusable after 1 or a number of impacts

The force of hitting your head in a bike accident could be even greater than the force of a hit in football, and yet foam and plastic are the go to??
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Old 11-22-19, 11:16 AM
  #29  
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Originally Posted by Flip Flop Rider View Post
I hear ya, and I'm not advocating using football helmets, just saying that helmet designers could incorporate some of that technology in a bike helmet. People would pay more if they were better and reusable after 1 or a number of impacts

The force of hitting your head in a bike accident could be even greater than the force of a hit in football, and yet foam and plastic are the go to??
Not a marketing person or an engineer, but I suspect that you can have a helmet be 2 of the following, but not all 3: , durable, practical, and affordable.

I'm pretty sure @mr_bill cited data that showed that "can't afford" is the most frequent reason people give for not wearing helmets, I seriously doubt that "have to replace if I get into a crash" is even close.

Other than breakability, what's wrong with foam and plastic? What's actually "better"?
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Old 11-22-19, 11:17 AM
  #30  
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Originally Posted by Flip Flop Rider View Post
People would pay more if they were better and reusable after 1 or a number of impacts
People do pay more. Look for Expanded Polypropylene (EPP) helmets. These are multi-hit helmets, often for multiple wheeled sports, so often with multiple standards certifications.

Example from POC.

Damning with faint praise, they are more comfortable than the old Bell Tourlite.

-mr. bill
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Old 11-22-19, 12:31 PM
  #31  
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Bike helmets are way overrated in terms of protecting your brain from impact. What the helmet does do fairly well is protect the skin, soft tissue structures, and bone or skull that the helmet covers. The protection of the brain itself is much less.
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Old 11-22-19, 01:06 PM
  #32  
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Originally Posted by mr_bill View Post
People do pay more. Look for Expanded Polypropylene (EPP) helmets. These are multi-hit helmets, often for multiple wheeled sports, so often with multiple standards certifications.

Example from POC.

Damning with faint praise, they are more comfortable than the old Bell Tourlite.

-mr. bill
Excuse my ignorance, but how does wearing EPP compare to EPS? Doesn't look like anyone makes a road bike helmet from it.
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Old 11-22-19, 01:35 PM
  #33  
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Originally Posted by Flip Flop Rider View Post
I hear ya, and I'm not advocating using football helmets, just saying that helmet designers could incorporate some of that technology in a bike helmet. People would pay more if they were better and reusable after 1 or a number of impacts


The force of hitting your head in a bike accident could be even greater than the force of a hit in football, and yet foam and plastic are the go to??

The one-time hit and comfort are driving factors in design of these foam bike helmets. Also, the anticipated speed is often cited but take that with a grain of salt. I don't know about you, but I am way more interested in protecting myself better from a high speed crash than having something marginally better at 6 mph. Anyone would - I think that there's a bit of smoke there.


Different sports have different standards, but the minimum standards are pretty much converging at least for the g-force allowed.


That said, though it's been awhile since I wore a motorcycle helmet I recall that they are larger with more material, plus the hard shell of course, and I believe that they offer more protection at any speed. We don't wear them because they're hot and heavy relative to bike helmets - uncomfortable when we're going hard. Bicycle helmet may have an aerodynamic edge.


It's kind of ironic that these are the same reasons why some of us (including myself) sometimes don't wear a bicycle helmet. Whether you choose not wear one, or choose to wear one but not a motorcycle helmet, it's a trade-off between comfort and protection.
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Old 11-22-19, 03:12 PM
  #34  
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Originally Posted by wphamilton View Post
The one-time hit and comfort are driving factors in design of these foam bike helmets. Also, the anticipated speed is often cited but take that with a grain of salt. I don't know about you, but I am way more interested in protecting myself better from a high speed crash than having something marginally better at 6 mph. Anyone would - I think that there's a bit of smoke there.


Different sports have different standards, but the minimum standards are pretty much converging at least for the g-force allowed.


That said, though it's been awhile since I wore a motorcycle helmet I recall that they are larger with more material, plus the hard shell of course, and I believe that they offer more protection at any speed. We don't wear them because they're hot and heavy relative to bike helmets - uncomfortable when we're going hard. Bicycle helmet may have an aerodynamic edge.


It's kind of ironic that these are the same reasons why some of us (including myself) sometimes don't wear a bicycle helmet. Whether you choose not wear one, or choose to wear one but not a motorcycle helmet, it's a trade-off between comfort and protection.
I'm pretty sure that if I tried to "go hard" wearing a motorcycle helmet on a hot day, I'd have a heat stroke. It's a bit more than just a comfort thing.
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Old 11-22-19, 03:49 PM
  #35  
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Anyone who suggests wearing a motorcycle helmet on a bicycle should be taken with a 3 pound box of Diamond Crystal Kosher Salt.

-mr. bill
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Old 11-22-19, 05:14 PM
  #36  
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I think if someone wanted to wear a motorcycle helmet, and didn't mind the heat, I for one wouldn't bad-mouth him. I'm not in the least tempted myself however.

I think I saw a photo of some hard-shelled bike helmet here on this thread earlier ... maybe there are some vent holes but it's still hotter that the vented bike helmets ...
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Old 11-22-19, 06:03 PM
  #37  
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Originally Posted by wphamilton View Post
I think if someone wanted to wear a motorcycle helmet [on a bicycle], and didn't mind the heat, I for one wouldn't bad mouth him.
How “noble!” The null set!

Similarly, I for one wouldn’t bad mouth anyone who chose to wear a shower helmet, stair helmet, sidewalk helmet, ....

....The people who suggest such nonsense on the other hand....

-mr. bill
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Old 11-22-19, 07:53 PM
  #38  
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Originally Posted by mr_bill View Post
How “noble!” The null set!

Similarly, I for one wouldn’t bad mouth anyone who chose to wear a shower helmet, stair helmet, sidewalk helmet, ....

....The people who suggest such nonsense on the other hand....

-mr. bill
Who suggested it? I don't see it, and it's kind of annoying for you to crap on the thread like this.
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Old 11-22-19, 09:12 PM
  #39  
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Well, to me the elephant in the room is contrecoup injury. These helmets, whatever their technology, only address the coup injury. The only solution to keeping the brain from slamming into the opposite side of the skull is prevention, as far as I know. And I don't know anyone who knows how to prevent bicycle crashes.
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Old 11-22-19, 09:21 PM
  #40  
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Originally Posted by wphamilton View Post
Who suggested it? I don't see it, and it's kind of annoying for you to crap on the thread like this.
Originally Posted by wphamilton View Post
These are interesting topics but I'm personally not going off on tangents on this thread. Anyone else feel free.
FWIW, when you brought up motorcycle helmets, flush....

-mr. bill
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Old 11-22-19, 09:41 PM
  #41  
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Originally Posted by wphamilton View Post
The one-time hit and comfort are driving factors in design of these foam bike helmets. Also, the anticipated speed is often cited but take that with a grain of salt. I don't know about you, but I am way more interested in protecting myself better from a high speed crash than having something marginally better at 6 mph. Anyone would - I think that there's a bit of smoke there.


Different sports have different standards, but the minimum standards are pretty much converging at least for the g-force allowed.


That said, though it's been awhile since I wore a motorcycle helmet I recall that they are larger with more material, plus the hard shell of course, and I believe that they offer more protection at any speed. We don't wear them because they're hot and heavy relative to bike helmets - uncomfortable when we're going hard. Bicycle helmet may have an aerodynamic edge.


It's kind of ironic that these are the same reasons why some of us (including myself) sometimes don't wear a bicycle helmet. Whether you choose not wear one, or choose to wear one but not a motorcycle helmet, it's a trade-off between comfort and protection.
A problem with aerodynamic bicycle helmets is that the more aerodynamic they are the more chance there is for the bicyclist wearing one to suffer a rotational head injury.

What surprised me when I was researching MOST helmet designs is that they were NOT really designed to prevent a concussion. My understanding is that a MIPS helmet is a bit better but again not a whole lot better.

Cheers
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Old 11-22-19, 10:09 PM
  #42  
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Originally Posted by Miele Man View Post
A problem with aerodynamic bicycle helmets is that the more aerodynamic they are the more chance there is for the bicyclist wearing one to suffer a rotational head injury.

What surprised me when I was researching MOST helmet designs is that they were NOT really designed to prevent a concussion. My understanding is that a MIPS helmet is a bit better but again not a whole lot better.

Cheers
Yeah the long tail in the back of aero helmets would be problematic it they hit the ground. I was thinking more simply, of the regular bike helmets, with I believe a smaller cross section facing the wind. That could make them slightly more aerodynamic than motorcycle helmets, depending on how the vent shapes affect it.

When MIPS first came out I thought it was a very good idea, but without data proving that it helped prevent concussions the jury was still out on it. It's been a while, and there might be more information now, but I don't think anything very solid has been proven yet.
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Old 11-23-19, 02:44 AM
  #43  
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Originally Posted by wphamilton View Post
Yeah the long tail in the back of aero helmets would be problematic it they hit the ground. I was thinking more simply, of the regular bike helmets, with I believe a smaller cross section facing the wind. That could make them slightly more aerodynamic than motorcycle helmets, depending on how the vent shapes affect it.

When MIPS first came out I thought it was a very good idea, but without data proving that it helped prevent concussions the jury was still out on it. It's been a while, and there might be more information now, but I don't think anything very solid has been proven yet.
Thank you. You allude to a very good point, which is, the difficulty of actually carrying out a properly designed helmet safety study in humans. Ideally, we would prefer to see a randomized, placebo-controlled, double-blind study, because they are generally the gold standard. But that is just never going to happen in any compassionate, sensible country. For some users, that would be like agreeing to enter a study where they could be randomized to no seatbelt or no air bag or no antibiotics for pneumonia. Some people just will not do that, understandably. I you are perfectly healthy and love your WaveCel or MIPS or SPIN, you are not going to take a chance on not having your helmet on in the event you crash in the name of science, regardless of how noble and selfless you may be. So, then, I suppose we would probably be stuck with a retrospective look at accident crashes. But how does that get done? I live in one of the most pro-cycling cities on the planet, but we certainly don't have any kind of registry of accidents and victims. There is no mandatory reporting. Does your city, state, province, or prefecture have such a registry?

I would think that mandatory accident reporting would be almost a requirement in order to collect enough decent data for a retrospective study to have any kind of power. Maybe that will happen in some progressive and thoughtful locality somewhere. Until then, we are stuck with just random reporting of random events. And that isn't getting us any closer to the truth.
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Old 11-23-19, 07:00 AM
  #44  
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Originally Posted by bpcyclist View Post
Thank you. You allude to a very good point, which is, the difficulty of actually carrying out a properly designed helmet safety study in humans. Ideally, we would prefer to see a randomized, placebo-controlled, double-blind study, because they are generally the gold standard. But that is just never going to happen in any compassionate, sensible country. For some users, that would be like agreeing to enter a study where they could be randomized to no seatbelt or no air bag or no antibiotics for pneumonia. Some people just will not do that, understandably. I you are perfectly healthy and love your WaveCel or MIPS or SPIN, you are not going to take a chance on not having your helmet on in the event you crash in the name of science, regardless of how noble and selfless you may be. So, then, I suppose we would probably be stuck with a retrospective look at accident crashes. But how does that get done? I live in one of the most pro-cycling cities on the planet, but we certainly don't have any kind of registry of accidents and victims. There is no mandatory reporting. Does your city, state, province, or prefecture have such a registry?

I would think that mandatory accident reporting would be almost a requirement in order to collect enough decent data for a retrospective study to have any kind of power. Maybe that will happen in some progressive and thoughtful locality somewhere. Until then, we are stuck with just random reporting of random events. And that isn't getting us any closer to the truth.
Trials in this area would not be placebo or sham controlled, they would be comparative effectiveness trials and these are done all the time. The ethical threshold is whether there is “equipoise,” that is, an honest lack of knowledge, on the relative effectiveness of the helmet types. The big problem with this kind of research is the statistical difficulty of proving differences in effectiveness between two effective treatments.

A more effective, but also ethically fraught, way to answer the question is with a primate concussion model. Essentially everything we know about the mechanism of concussion today came from one lab at Penn, which was shut down in the 1980s for mistreating their animals. If it were decided that the social need was high enough and that the research could be done in an ethical manner, this would be the way to go.

Registries are great and the need is obvious, but concussion is hard to characterize with a single, cross-sectional, look, and there are hundreds of helmet types out there.

Last edited by MoAlpha; 11-23-19 at 07:04 AM.
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Old 11-23-19, 08:48 AM
  #45  
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Originally Posted by MoAlpha View Post
Trials in this area would not be placebo or sham controlled, they would be comparative effectiveness trials and these are done all the time. The ethical threshold is whether there is “equipoise,” that is, an honest lack of knowledge, on the relative effectiveness of the helmet types. The big problem with this kind of research is the statistical difficulty of proving differences in effectiveness between two effective treatments.

A more effective, but also ethically fraught, way to answer the question is with a primate concussion model. Essentially everything we know about the mechanism of concussion today came from one lab at Penn, which was shut down in the 1980s for mistreating their animals. If it were decided that the social need was high enough and that the research could be done in an ethical manner, this would be the way to go.

Registries are great and the need is obvious, but concussion is hard to characterize with a single, cross-sectional, look, and there are hundreds of helmet types out there.
I think that with the great advances in electronics that a full dummy with sensors in the head could be built and used to determine the likelihood of a concussion. Then a bicycle helmet could be a lot better designed provided it didn't become too heavy or hot to actually use. Helmets could be tested on that dummy instead of on the current detached head-form.

The detached head-form tests don't take into account the extra motion to the head that a falling body imparts where the body acts like a fulcrum.

Cheers
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Old 11-23-19, 10:40 AM
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Originally Posted by bpcyclist View Post
I had not heard about UV light degrading helmets. How does that work?
It’s the combination of oxygen and UV radiation that causes the problem. The combination of the two results in photooxidation of the polystyrene molecules. UV causes oxygen to form free radicals in the polymer by splitting the bonds. Oxygen reacts with the radicals and weakens the polymer. It would be a mistake to assume that the damage is only done to the outer most parts of the polystyrene, however. The entire process causes embrittlement of the styrene throughout the helmet and reduces it’s ability to crush and absorb the energy of impact.
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Old 11-23-19, 11:15 AM
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Originally Posted by cyccommute View Post
It’s the combination of oxygen and UV radiation that causes the problem. The combination of the two results in photooxidation of the polystyrene molecules. UV causes oxygen to form free radicals in the polymer by splitting the bonds. Oxygen reacts with the radicals and weakens the polymer. It would be a mistake to assume that the damage is only done to the outer most parts of the polystyrene, however. The entire process causes embrittlement of the styrene throughout the helmet and reduces it’s ability to crush and absorb the energy of impact.
That is so interesting, thank you. So, but, that would suggest if I live in San Diego or Barcelona that my time frame for helmet replacement should be quite a bit different than if I live in Manchester or Seattle, right? Do you think the bike shops in sunnier climates know this?
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Old 11-23-19, 11:24 AM
  #48  
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Originally Posted by cyccommute View Post
It would be a mistake to assume that the damage is only done to the outer most parts of the polystyrene, however. The entire process causes embrittlement of the styrene throughout the helmet and reduces it’s ability to crush and absorb the energy of impact.
And it’s not just UV, heat-cold cycles, water (particularly salt), chemicals from sunscreen....

Not to mention shampoo and conditioner.

-mr. bill
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Old 11-23-19, 11:29 AM
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Originally Posted by bpcyclist View Post
That is so interesting, thank you. So, but, that would suggest if I live in San Diego or Barcelona that my time frame for helmet replacement should be quite a bit different than if I live in Manchester or Seattle, right? Do you think the bike shops in sunnier climates know this?
Probably not. Just like auto tire shops don’t know that this is an issue for them and their customers as well.

-mr. bill
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Old 11-23-19, 11:56 AM
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Originally Posted by cyccommute View Post
It’s the combination of oxygen and UV radiation that causes the problem. The combination of the two results in photooxidation of the polystyrene molecules. UV causes oxygen to form free radicals in the polymer by splitting the bonds. Oxygen reacts with the radicals and weakens the polymer. It would be a mistake to assume that the damage is only done to the outer most parts of the polystyrene, however. The entire process causes embrittlement of the styrene throughout the helmet and reduces it’s ability to crush and absorb the energy of impact.
The studies that I rely on all show insignificant degradation except near the surface of polystyrene foam, particularly with UV coating. In practical terms, the testing showed that you'd have to leave it out for at least several months to have any effect on hardness and brittleness deeper than a surface layer.

BTW, as an aside it's relatively chemically inert aside from solvents.

Last edited by wphamilton; 11-23-19 at 11:59 AM.
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