vol

I'm surprised it is allowed by the moderators on this forum. Not a place for me to be, I see.

FBinNY 

I'm sure the moderators would have blocked it if it were spelled out, or at least the first word, but lots of stuff gets past the radar.

I have very mixed feelings about the A&S forum which has a long history or contentiousness. From what I hear, it's very tame these days compared to when it was the Wild West. I spend most of my time on the mechanics forum, and we may get personal once in a while, but it's the exception and not the rule. But I sense that there more passion here than in the cut n' dry world of mechanics.

Don't let people drive you off, and don't take anything personally, even if it's intended so. Just be sure to wear your Teflon coated Kevlar vest and ballistic helmet when posting.

If you can ride your bike among the taxis, buses, and crazy people in NYC, this is a stroll in the park.

mconlonx

Report me to the mods if you are offended, it's been a while since I've received an infraction.

In the meantime, maybe read some of this thread and kindly refrain from broad, sweeping, prejudiced generalizations. Especially when they are essentially incorrect.

vol

Thank you, FBinNY. I need a carbon mask.

Edit: FBinNY, I just noticed your last signature line.

rekmeyata

Why is it on their site: https://www.pocsports.com/en/14/wheels-helmets that helmet is not listed for sale? I'm not sure if POC helmets are the safest, just a different design from a different helmet company, and that helmet doesn't offer the MIPS protection whereas a couple of models of other POC models and one or two of the Scott helmets do. I'm not so sure I, that's me, myself, and I, would "want" that particular helmet. I pretty sure that the next helmet I buy will have the MIPS technology unless something comes out to disprove it's effectiveness or something better comes along.

mconlonx

Probably because it is a new intro for 2014 and is not for sale yet, thus not on their site? If you clicked through to the original reference, you'd find the site name is bikerumor...

rekmeyata

There is a new helmet absorption material, instead of styrofoam or EPS liner it's simply cardboard which is said to absorb 3 times the energy that current liner material does, and test showed it not only survived one impact that will kill a styrofoam or an EPS liner but survived 5 consecutive impacts! Problem is I can't find one of them for sale.

License2Ill

Sounds great, but it won't change anything until a standard that bears out significant improvements is used to test it. The thing is, as always, the real question is not about energy absorption, it's about applying a braking force over time to limit the force the brain experiences during the impact event. With the the understanding of survivable levels of force the brain can withstand, the important questions are not one of withstanding multiple impacts, but the level of impact energy you can throw at it while maintaining the level of g's the brain can withstand.

Keep in mind, the last time anything was done to change a standard, it was going backwards from Snell B90 to CPSC with a big industry push towards lighter requirements and honor system testing from the factory. So we're a long way off from seeing any factual claims of options that provide more protection, especially with type of obfuscating debate that comes with it from those that think better options will force them to capitulate.

FBinNY 

Regardless of the material used, the impact absorbing property is determined by crush distance (slightly less than total thickness) and crush rate. At any impact speed the goal is to have the head slowed to zero within the crush distance. If the crushable material is stiff it may slow the head too fast and not use all available distance. OTOH if the material crushes too easily, the entire crush distance will be used before the head is slowed to zero causing a nasty surprise at the end.

It's comparable to landing an airplane on a runway. Apply the brakes too hard, and you'll stop soon enough, but the passengers will be prying their faces off the seat backs in front of them. Apply the brakes too gently, and you run out of runway. Obviously, the longer the runway (thicker crushable material) the gentler the stop possible.

Since there's a limit to how much helmet folks will willingly wear, designers have to decide the impact speed range to engineer for. Engineer for high impacts and the helmet will offer limited benefit at low impact. Design for low impact, and it's useless at higher impacts. In any case the stiffest crush rate is limited by the amount of G-force the brain can tolerate, so there's a practical limit to what helmets can do.

The material itself doesn't matter, except to the crush rate possible, and the weight. Then it's how much thickness you're willing to wear.

Reynolds 

"Nanny state"

License2Ill

I'm surprised by how much is right with this post, but in terms of designers deciding what type of impacts or speeds involved, that is not really something they design for within current thresholds. With standards established, they are always designed with the ideas of lighter weight and more ventilation or aerodynamic considerations within the current parameters of maintaining the ability to handle the flat and hemi anvil hits of the basic CPSC requirements. Too hard isn't a current issue at all, unless they are trying to pass off a construction hard hat with no crush material and neither is too soft with thin shells seen in current offerings.

If we look at motorcycling helmets, we see where both shell thickness and EPS thickness are increased to deal with harder impacts, again within the accepted size, weights, and ventilation capabilities. Though there was somewhat recent concern over the hardness of some specs, all those standards used for mc helmets are now congruent with regards to smaller head sizes and lower head weights where there was a divergence between standards that allowed for thinner shells, and thus lower g's in flat surface impacts.

FBinNY 

I used the term "designers" in broad sense to include the engineering and cosmetic design both. Where there are standards, it would include those who "design" the standards.

BTW- I might add, that while a thicker helmet would increase the available crush distance, it has it's own problem besides customer acceptance. As the radius of a helmet increases, the likelihood of impact does too, as does the torque created on angular impacts, increasing the risk of neck injury.

Joe Minton

FBinNY & License2Ill -- Wonderful! -- It is so good to read rational comments. I hope other fact seekers join in. Bicycle helmet design is a serious subject and deserves sober consideration.

It is also a complicated one: I know most of the factors that determine helmet design and there are many. I'd love to share what I've learned about them since '66 (middle of the last century).

Not many of the fundamental design considerations have changed: an unmitigated fall from five or six feet is still usually fatal; EPS (Styrofoam) is still the best practical acceleration attenuator; Double strikes on the same spot of a helmet continues to be very rare, etcetera.

One thing that has changed in the past couple of decades is our understanding of just how fragile our brains are. When I witnessed bicycle helmets tests (1984) conducted at the University of Southern California by David Thom under the supervision of Professor Hugh "Harry" Hurt, the accepted threshold standard of immediate and permanent brain injury was 350gs (If I remember correctly), 400gs was guaranteed to produce permanent and very significant damage, 200gs was basically ignored.

We now know that while 150-200gs may not result in immediate and obvious injury, if experienced enough times, terrible damage will be done. Witness the problems of retired NFL players.

Something about the fragility brains:
Television crime shows often feature a medical examiner carrying a human brain around in his hands as though it were a large chuck roast. Tain't so folks. The usual practice, as I understand it, is to first carefully sever the tiny blood vessels’ running between the brain and skull, fit a net around and under the brain then, using the net, gently lift the brain enough to reach in and sever the spinal cord and finally very carefully remove the brain using the net. Brain tissue has the consistency of barely-set scrambled eggs. Think about that. It's a wonder I ever made it into adulthood (some would have it that I'm not entirely there yet) ;o)

Joe

FBinNY 

Fact is we only scratched the surface. As you point out new research is now discovering the effects of multiple sub clinical injuries, ie. football players, and boxers. We're also learing how uniquely vulnerable the neck, head and brain are to sudden angular acceleration (torsion), and that the injury threshold for this is very low.

Much more research is needed, but while we focus on mitigating injury, there's little discussion on preventing it in the first place.

head strikes aren't spread out equally among cyclists. While a "lightning strike" can happen to anyone at any time, the fact is that some (most) cyclists go for lifetimes without serious injury (head or otherwise), others have multiple injuries, This isn't simply a matter of more riding, = higher risk, there are other factors at play.

Unfortunately the entire safety debate is focused on "wear a helmet" and there's little or no discussion of how to reduce the chances of the type of crash that tends to cause serious injury.

IME, the risk or serious injury cyclong in cycling is more closely tied to what's in your head, not what's on your head. Helmet or not, ride smart.

mconlonx

Actually, LAB claims that more riding = lower risk. The more you ride, the more different conditions you ride in, the more experience you have riding, the less likely you are to crash. The less likely you are to crash, the less likely you are to sustain a head injury.

"Wear a helmet" is #5 , last on their list of five things you can do to ride safer.

This particular thread, however, is not the "how to ride your bike safely" thread, it is "The Helmet Thread."

Riding safely is a software issue, an argument could also be made that it's also a firmware issue -- not just what's in your head, but what comes natural to you, such as obstacle avoidance and traffic scanning practice. <-- Not helmet related, very tangential to this thread...

sudo bike

Worthy of note here is that these are repeated impacts, consistently, over years of play. Most riders under normal riding conditions are going to experience very, very few impacts, if any, to the head. The NFL is a bit of a different issue, since the controversy surrounds what is happening to players as they take these impacts over time. That really isn't so much a consideration here. We don't need to worry about mitigating damage of impacts over time, so much as we need to worry about immediate trauma (unless you're doing some sort of cycling where you might crash as a matter of course... BMX stunts, etc).

I-Like-To-Bike

Did LAB provide any details about how they reached this conclusion, other than guessing that more riding may be associated with maturity and/or less risky cycling habits?

FBinNY 

I don't know what LAB used, but many years ago (the seventies or eighties) there was data collected correlating the bicycle accident/injury numbers with growth trends in the sport. When the sport is growing, the accident rate rises faster. When the sport isn't growing, the accident numbers fall even though ridership stayed constant. The implication is that new cyclists are more likely to have accidents and/or suffer injuries.

There are parallels in other activities, from fighter pilots during WWII, to diving, to car drivers. If you survive the early experience,you come out better. Of course it could be debated whether this is simply a natural selection process, or whether Nietzshe was correct in saying that what doesn't kill you makes you stronger. Either way experienced cyclists tend to be survivors.

License2Ill

The basic point is that there is a heavy penalty with a fall that involves a head impact. How those falls happens matters less to the idea of a helmet for when they do occur. It's pretty simple, a helmet is designed to make a fall to ground survivable in terms of head injuries. They are capable of that. Arguing that not wearing one is a better idea because they don't do as well when hitting a brick wall at the speed of sound is pretty silly, especially in the face of folks that have died as the result of a head injury while riding. It's happened enough times to enough people to know that it's a good idea whether we've avoided those impacts to date or not. If the argument was that current designs are doing something that keeps something better off of your head, then someone might have a valid point, but they simply offer a better alternative than hitting the ground without one in terms of a clear line between surviving and not surviving. They can't make pancakes for breakfast.

FBinNY 

I can't speak for others, but even though I don't feel the need is high enough to wear them, I've never once, here, or in any context argued that they don't help mitigate injuries. Of course they do. However, the general impression is that they do more than they can, and over the last two decades the notion - wear a helmet - has crowded out other discussion of staying safe (not here, but in general).

I get the "where's your helmet" from kids riding new fixies without brakes, from guys riding in ragtag packs running lights like they were on closed roads. I get lectured by folks who tell me that a helmet saved their life times. Three times!, really? Yes helmets provide safety, but are not a raeasonable replacement for some common sense, and due care when riding.

License2Ill

It is a matter of leadership for kids too. Kids are generally not only more likely to be riding, but also more likely to crash and crash poorly. I hope any kids seeing me riding take note of the helmet rather than the cigarette, even though their parents may be telling them to wear one already. Nobody is calling a helmet a replacement for any broad term of common sense or anything else. People are just calling it a good and worthy idea to wear one, and to take due care as well. Some folks may also be in to seeing more dedicated bike lanes on roads, trails, and other advocacy as well. It's not an all or nothing proposition. The only all or nothing proposition is when you need a helmet and are not wearing one.

DNP

Ignoring some of the exceptions for a second, a helmet will always mitigate injury to your head. That doesn't change when you dismount your bike, walk up some stairs in flip flops, and step into a slippery porcelain shower, right? All that changes throughout the day is relative risk of injury based on what you are doing at that moment in time. Donning a helmet 24 hours day is considered ludicrous, so we pick and choose when. Your position backs you into the ideological corner of wearing one every second of the day because "The only all or nothing proposition is when you need a helmet and are not wearing one". I wear one when I think it's appropriate, I bet you do too.

mconlonx

Yes, there were all kinds of supporting graphs, showing years of experience vs crashing, miles riding/year vs crashing, age, etc. Something like, a rider who has been cycling for a year will crash once in 2000 mi; a rider with ten years experience will crash once in 8000+ miles of riding.

Basically, the more you ride the less your chances of crashing... which makes sense. More experience in more varying conditions makes for a safer rider.

Regardless of helmet use.

I-Like-To-Bike

Did any of this "crash" data include the severity of injuries involved? Conclusions about bicycle safety/risk focusing on total number of "crashes" without the accompanying severity data is close to worthless.

3alarmer 

.....that, my friend, would be a product that we could sell in volume.

The Ronco Helmet Pancake Maker...........as seen on TV.