Redhatter

Hi all,

About a fortnight ago, a work colleague of mine had a serious crash which left him with severe head trauma, he passed away on Wednesday afternoon. This has triggered me to start a project investigating the designs and standards of bicycle helmets to see if they can be improved.

The project is on Hackaday.io: https://hackaday.io/project/9831-improved-helmets

I figured I'd mention it here since many of us cycle long distances, and even use it as a primary mode of transport. (Next month, my house hold will be car-free.) Thus I figure people have a vested interest in their safety equipment working as advertised.

Some of the things I'm looking into:
- I've read up the Australian Standards for both bicycle and motorcycle helmets, and it's rather eye opening. I'm curious to see what standards look like elsewhere in the world.
- The comment was made that severe head trauma (particularly where the brain gets shaken around in the skull), is a common issue. This is worrying to me, and I'm trying to gather data that could either prove or disprove that point. If people know of places where I can try asking, that'd be appreciated (I've already approached Queensland Transport and Queensland Health… I have some data from NSW Roads and the Austalian Institute of Health and Welfare.)
- If people have some ideas as to how we can (1) model the effects of crashes on the skull and brain, and/or (2) how to design a helmet that takes these effects into account, I would appreciate your help.

The goals of the project:
1. To gather statistics that can be used as evidence to push for improvements in designs and standards.
2. To devise a suitable model for analysing the effects on the brain and skull with a view to measuring the effectiveness of helmet designs
3. To devise a public-domain design that tries to improve the survival outcomes in crashes which may be implemented by any helmet manufacturer, royalty free.

Those wishing to get on board, feel free to contact me either here or on the project site.

Looigi

Check this: Helmets: Bicycle Helmets

FBinNY 

FWIW - you're trying to "explore" well traveled terrain. Plenty of work has been done in this area, and what you see is the result of balancing protection against "wearability". I'm not saying helmets can't be improved on, just suggesting that you start your research in the library and see what's been done so far.

There's also a bit of a catch-22 about helmets that nobody wants to discuss. Helmets enlarge your head, both increasing the chances of a head strike, and the rotational forces which are a major cause of TBI. I don't say this as an anti-helmet argument, but as a reminder that there are design limitations to be factored. As you increase helmet size to improve energy absorption, you increase the chance of a strike where it might not otherwise have happened.

OTOH- I may be the wrong person to advise here. I consider bicycles to be extremely safe, and the total risk of head injury low enough that I don't bother with helmets.

vol

OP (yes I remember you mentioned that tragic accident in another discussion), it would be better if you use a larger font size on your website. Tiny texts on black background may turn away some readers.

P.S. Helmet is a defensive, not preventive measure. Most important and effective safety measure is a good infrastructure, so good that one is safe without helmet.

Redhatter

Yep, I did see one of the pages there, and I've been having a good look at some of the others. Their comments on the MIPS standard is interesting.

Yeah, this is true. As I mention in one of the posts, something the size of a beach ball is not going to fly no matter how good it is.

I wear an open-face motorcycle helmet because I thought of bicycle helmets as too "flimsy". It's not much bigger than a bicycle helmet, a bit heavier, but I feel the ability to withstand multiple strikes versus just one will win out.

The traditional design though has been one with a liner that deforms permanently, and I just wonder about how much they deform on impact. Seems as if we need to begin slowing the head's movement down a lot sooner, thus maybe the current designs need to be turned "inside out" with softer material outside. That's just an early thought though, hence the project.

Yeah I can't control the font size or page style, it isn't "my website". I put it there rather than on my own as I want to encourage collaboration, anyone can join Hackaday.io and request to join the project. Not so easy doing it that way on my blog.

CrankyOne

The best protection is to prevent the crash in the first place with better road design and protected separated bikeways. This is the approach of The Netherlands and many other countries and is why they have less than 1/10 the injuries and fatalities that we do. Sadly no helmet short of full plated body armor will be effective in an incident between a 4000 lb car traveling at some speed and a 200 lb bike rider.

canklecat

The primary risks in head trauma are open or penetrating head injury (skull fractures, or objects penetrating into the brain) and closed head injury. Concussions are the most common among the latter, but subdural hematomas and other injuries can occur.

It's relatively easy to design a helmet that minimizes the risk of open head injury. A hard shell with little padding can do that.

The tricky bit is designing a practical helmet that can slow down the impact enough to minimize the closed head injuries.

Plenty of padding works. Those air inflatable sumo suits are an example. Not practical for most purposes, but safe and cheap. Martial arts have developed some reasonably effective physical padding devices to reduce injuries: heavy bags rather than thinly padded wooden balls that mimic the skull; gloves to reduce hand injuries and, to a lesser extent, injuries to the recipient of the blows; headgear to reduce "cuts" (actually split skin over bone). But these are heavy, absorb moisture and intended more to minimize surface, externally visible injuries. Padding can reduce the risk of the recipients of blows suffering grotesque swelling and cuts, but closed head injuries can still occur. It just looks less horrific to viewers.

Those lightweight styrofoam beer coolers we wear as bicycle helmets that make us look like insects or crustaceans are already an effective compromise between safety and practicality. Beyond a certain point cyclists won't wear them, so the best helmet won't be worn. The thin plastic shell is reasonably well designed to reduce the risk of open head injury by deflecting blows against curbs, bumpers and fenders, that sort of thing. The styrofoam cushions help decelerate the impact, reducing some of the risk of closed head injury.

You can add more air pockets to the styrofoam (yeah, I know, technically it's not styrofoam) but it'll make the helmet larger and less practical to the point cyclists won't wear it.

You can add something like gel inside the foam, but it will increase weight, again reducing practicality.

I'll wear a helmet and be grateful for whatever protection it does offer. But realistically my biggest risk will be paralysis or death from a broken neck if I crash. My C2 vertebrae was splintered in a car wreck 15 years ago and there ain't much bone supporting my gigantic noggin anymore. Wouldn't take much of a head blow to finish the job. If it happens, I just hope it's quick and painless. But because of chronic and occasionally severe neck pain I can't support much weight on my head or shoulders. So while I'd welcome a better practical helmet, it can't be much heavier than the current models (all under 500 grams, if I'm recalling correctly), or it will be too heavy to wear comfortably.

Redhatter

This is true, however in the case of my colleague, he crashed on an off-road bikeway where the Go Between Bridge joins the Bicentennial bikeway. For a car to have hit him, it'd have to jump a 1m high concrete barrier and an air gap of about 2m.

CrankyOne

That's tough. And extremely rare. IIRC in the U.S. it's less than 1 in 700 cyclist fatalities and serious injuries caused by something other than being hit by someone driving a car. EG, for every one fatality or serious injury caused while riding off-road or on a MUP there are about 700 caused by someone driving a car and hitting a cyclist on the road so from an overall standpoint preventing cars from hitting people riding bicycles will have the much greater impact.

Not sure what it looks like in Oz but I'd guess very similar. Something else to consider is that the rate of head injuries (as a percent of all serious injuries for cyclists reported to hospitals) did not change when mandatory helmet laws were implemented and helmet wearing in Oz went from an estimated less than 10% to over 90%. The later largely speaks to the ineffectiveness of current helmets that you are trying to address but I believe you have a tough to impossible task.

BTW, I think the problem you're trying to solve likely falls in to the same category as people killed or seriously injured when they slipped in the shower, hit their head when they stumbled over a bump in a sidewalk, or fell down some stairs. The risk of serious injury is not normally very high.

On top of this, as mentioned above, you've the conundrum of effectiveness vs comfort. The only known way to reduce incidences of TBI is an extremely hard outer shell that will not crack or dent on impact with layers of varying densities of foam between that and the persons skull. EG, a motorcycle type helmet. This is the only known effective way to reduce the movement velocity of the persons head slow enough to prevent concussion (which is the problem of a skull moving at some speed, like 10 mph, coming to a sudden stop while the brain inside continues at 10 mph and concusses against the inside of the skull). Anything less has not been shown to be effective.

Then you must layer on spinal injuries which are likely exacerbated by the wearing of a helmet. The solution to part one of this is bracing the helmet against the shoulders by either having it extend down low enough to touch the shoulders or attaching the helmet and shoulders to a fixed plane such as a drivers seat. Part two is rotational which involves a much more complicated restraint system (far beyond MIPS).

For the ultimate TBI protection system take a look at what has been done for Formula 1 drivers.

Redhatter

Indeed, I didn't think it was likely, but then it happened. This sort of accident just needs a lot of kinetic energy to be unleashed on the head -- physics doesn't care what supplies said kinetic energy, and it seems a man on a bicycle is more than capable of producing the needed energy himself.

Cars make the equation easier, by sheer virtue that the m in ˝mv˛ is big to start with and v can be pretty large, but even a cyclist can get v fairly high.

Yeah, I can only really hope to reduce the impact a little. If in this particular accident, my colleague wound up with concussion instead of winding up nearly brain dead, I'd consider that a result, as he'd still be sitting up in hospital now, and we'd be gathered around him asking: "Why did you take that corner so fast you silly galah?!" Instead of preparing for a funeral.

Protecting against all possible injury is unrealistic, and it may indeed be true that I cannot improve on what has been done so far.

It is true there has been millions spent on this sort of research, and work done by teams with much more in-depth knowledge than I have. F1 drivers are a good example of this, and there are certainly ideas there that could be applicable. I also have to be mindful of intellectual property, they've got more money than me, and could do some serious financial damage should they decide to take me to court.

Powered flight was not achieved by glider pilots, but by two bicycle mechanics. Even if I achieve nothing to actually improve standards, I will at least feel richer for the experience of having undertaken this journey.

It's a public project though, and I invite anyone interested, to come with me on this journey. :-)

02Giant 

^^^I believe you may be on to something with this thought process. ^^^
There is nothing that can be done to stop the brain from slamming against the inside of the skull. I believe dissipating the energy prior to the sudden stop is the key, but as stated, will it be practical.

corrado33

I think you guys are both wrong. Having the softer material on the outside of the helmet wouldn't help. First off, it'd be impractical as the helmet would be MUCH less durable. Every time you'd throw the helmet in the car and it bounces around it'd get dented up. Secondly, it doesn't matter where the soft material is. It's going to compress regardless. That compression is what's slowing your head down. There is no time difference between having the compression on the outside of the helmet vs. on the inside.

Imagine it like a balloon with a plastic plate and a weight behind it. If the entire assembly is dropped in order, the balloon will compress, absorbing some of the energy. If you reverse the order and put the plastic plate first, then the balloon, then the weight, the balloon still compresses in the same way. It doesn't matter if it's in front of or behind the plastic plate.

I think your best bet would be to develop a helmet with one of those airbag helmets inside of it. So when you crash the "airbag" helmet inflates and supports the head/neck.

mconlonx

Take a look at MIPS protection system.

wphamilton

"The goals of the project:
1. To gather statistics that can be used as evidence to push for improvements in designs and standards."

If this means crowd-sourcing the data, I think it's a good idea because data (and statistics) from bicycle accidents is notoriously sparse and inaccurate.

Just a suggestion. What you really need is data captured from actual accidents - bicyclists falling off and hitting the ground. I think that Hövding somehow captured some kind of similar data, more to determine when a fall was happening, but it's the one kind of data that researchers haven't collected, because they can't.

If you could design a small inexpensive accelerometer based capture device and convince enough people to attach it to their helmets (interfacing with a light weight phone app), some of them will eventually fall and you'll get the data. Followups with them after detected incidents will allow you to correlate the accelerations with injuries in a way that's never been directly tested. When you have enough of this data you can begin modeling of accidents and injuries, and perhaps improve helmet designs.

02Giant 

I will respectfully disagree as your method is commonplace in the helmet market, and for the most part doesn't work. Take sports helmets, typical construction is hard outer shell, semi compressible inner liner. Hard shell hits hard object, semi rigid foam liner absorbs some energy, but the sudden stop causes the brain to impact the inside of the skull. Football is an excellent example. My thinking, semi compressible outer material strikes hard object, some energy is absorbed, rigid inner-liner spreads the remaining energy over a broad area to eliminate point impact, semi rigid inner liner absorbs even more energy reducing the force of the brains impact on the inside of the skull.
I would compare it to NASCAR, years back "safety improvements" were mandated in the construction of the roll cages in the cars, stiffer, stronger roll cages, it sounded great but in practice there was a substantial increase of severe internal head injuries, and deaths from broken necks. You now had a car that was so stiff(strong) all of the energy from impacting the wall was transfered to the driver, where prior a lot of it was absorbed by the more complaint cage. HANNS Devices did wonders for the neck injuries but the "soft walls" in combination has made it almost certain the driver walks away from a 200 mph impact into a retaining wall.
I believe it will take an entirely different approach to the construction of helmets, I also believe you would see very few people wear the air bag helmet that was displayed a few years ago.

BTW, this is my opinion and I did not stay at a Holiday Inn last night.

corrado33

You can't compare it to a car. In a car accident there is so much more energy that the typically "hard" outer shell (metal body) is compressed like the soft part of a helmet would be.

The energy has to go SOMEWHERE. Your brain is STILL traveling at X MPH and STILL has to come to a stop. I actually think exactly the opposite of the way you do. If you have a hard inner liner, the liner will not conform to the head (unless, of course, it's molded to the user's head), therefore you'll get hotspots. If the liner is rigid it will STILL only compress the soft material that's in front of it. (Between it and the ground.) If you have a soft inner liner, as it compresses it contacts with more of your head and dissipates more energy (like what you were saying.) Basically, like I said before, it doesn't matter WHERE the soft material is. It get compressed regardless. It just makes a heck of a lot more sense to put it on the inside of the helmet (for comfort.) Besides, if you have soft stuff on the outside of the helmet it's more likely to get worn away (by asphalt) or torn away (by rocks/trees) than a hard plastic outer shell.

The sad truth is this. Bike helmets aren't big enough to provide adequate concussion protection in a serious bike accident. They need to be bigger. However if they're bigger no one would wear them. Hence my idea for "technology." Or rather "how to shove a bigger helmet into a smaller form factor until it's needed." Aka the airbag helmets.

Millions of dollars have gone into our current helmet design. Do you really think that if it was more beneficial to have the padded part on the outside of the helmet high risk people (race car drivers) would still be using hard shelled helmets?

And besides. If you had a "hard" inner shell, you'd need more padding to make it comfortable, essentially making a double layer, extremely large helmet that no-one would ever wear.

bronco71

https://en.wikipedia.org/wiki/Coup_contrecoup_injury

02Giant 

My helmet description was one of having three layers, either I didn't communicate that well enough or you didn't bother reading far enough into my response to reach that point.
You can compare it to a car, not a typical street car because they will absorb some of the energy from a crash. I was specifically citing NASCAR where they mandated stiffer roll cage assemblies that did not absorb engery, they transferred it.
Part of my reference to racing, NASCAR specifically, was they virtually eliminated the carear ending injuries when they made the retaining walls softer (how many millions had been spent prior on hard walls?). One of the biggest objections to the soft wall ideas in the beginning was just like yours, they will be damaged too easily. That hasn't been the case.

The solution to many issues is thinking outside of the box, current helmet design is a flawed box. I am not saying I am right, but neither are you.

corrado33

Why are you comparing current helmets to a car with NO crumple zones. The entire helmet is a crumple zone. The whole thing crumples when you hit something. Have you ever been in an accident with a helmet on? I have, the entire front half of my helmet broke into many squished pieces afterwards. Just because the foam isn't soft to the touch does not mean it will not crumple. The plastic shell provides literally no support and is just there for abrasion resistance and durability.

What proof do you have that a softer material wouldn't fall apart? You say it's not the case but provide no evidence for this.

The reason that car crumple zones are forward of the important bit (the person) is because it's impractical to surrounded the person in soft things! (Although they try with airbags.) Current helmets do not TRANSFER all of the energy. They absorb it. It's what they do. They've spent millions of dollars researching the correct material for this. It does not matter where you put that material. It will crumple regardless. Something the size of a current helmet will never be strides better than current helmets in terms of concussion protection. The only way to reduce that is to increase the time to "crumple." (Increasing the impulse. (Physics term)) The way to increase the time to crumple is to make the helmet larger or make the helmet material softer. That is impractical. If you make the helmet material softer then it will not be able to withstand a direct (head on) collision with a tree. Yes, spreading the load would be good (as it would increase the time to crumple), but if you make the material soft enough to take advantage of an inner hard shell like you're talking about, then it will lose out in other areas, namely sharp strikes with things like curbs/trees/stumps.

The hard shell on the outside does exactly what you're saying but for sharp strikes.

Redhatter

Ahh, healthy debate, I like it. :-) Thanks.

Bingo, that's the sort of injury I've been looking at.

This is an option. So far, I've tried to access what data I can, starting with what I can get through the Queensland Transport and Queensland Health.

Queensland Transport have informed me they can give me just about everything I need except the nature of injuries sustained — not sure if that's due to privacy concerns or just because they didn't record it. I'll see what I can get through Queensland Health.

Those are starting points that are in my local area. I of course am interested in areas other than my home state as well.

Crowdsourcing is also an option. First though, I'll see what's already there.

Yep, I have done. I also looked at Hövding, both are good concepts. I'm interested though if we can provide a competitor to MIPS. That might encourage more manufacturers to get on-board, especially if the alternative can be done cheap and royalty free.

Well, it depends on the materials concerned. You are right in that the material will compress anyway. The question I have in my mind is how much, and under what force? Then once the force is removed, what happens after that?

I tried analysing what happens in the AS/NZS 2068 tests: https://hackaday.io/project/9831-imp...-a-simple-case

I've approximately verified the flight time, I grabbed an old helmet, raised it to about 1.5m and dropped it. It seemed to travel for ⅓ of a second, so about right. Thus I'm fairly confident in my measurement of the strike velocity being 3.834 m/s in a downward direction. To me, key is trying to maximise the time it takes to go from 3.834 m/s to 0 m/s.

To do that over 100msec, you'd need 380mm of material: not practical.
To do that over 10msec, you'd need 38mm of material. The helmets I've seen, even my motorcycle one, have about 20mm of EPS foam.

Question is, is it really necessary to do it with EPS foam entirely? How about other materials?

I've been in touch with the Bicycle Helmet Safety Institute, and they pointed me to Bicycle Helmet Skid Tests by Voigt Hodgson in particular. So it seems sliding resistance against the road surface is a significant factor.

The thought I have thus is a 3 layer system:

- An outer low-friction layer, perhaps a few layers of perforated spandex/nylon that can tear away as the helmet slides, and/or a layer of some low-friction plastic.
- A crumple-zone of some softer conforming material, such as silicone rubber (possibly somewhere around hardness 50~60 on the Shore A scale at a guess) set up in a honeycomb structure to deform on impact
- A harder EPS or similar load-distributing layer as a means of last defence

That last layer could be an existing helmet that we simply make a cover for.

Depending on how much the EPS in a typical helmet deforms, it's possible that in a new design, that could be made a little thinner to make the overall helmet a more standard thickness incorporating the crumple-zone.

The real key here though is going to figure out how to model what's going on. I've been looking at what software's out there for doing finite element analysis, and Development of a Finite Element Head Model for the Study of Impact Head Injury describes how one might go about modelling the brain. FEBio and dealii are two such finite element analysis packages, the former targeted at biomechanics, so part of this will be learning how to drive them, then see what I can uncover.

Redhatter

Now this is an interesting read: https://www.onestreet.org/pdf/Bicycli...t-efficacy.pdf

Seems to be a lot on this topic: https://www.google.com.au/search?q=C...PMe70gTixJ3IAQ

It helps to know the right keywords, many thanks @bronco71.

bronco71

In generic terms you have a very simple engineering problem that is made complex by the human anatomy involved. Determining how much energy needs to absorbed / displaced is based upon;

E = 1/2 m v[SUP]2
[/SUP]E = dynamic energy (J, ft lb)
m = mass of the object (kg, slugs)
v = velocity of the object (m/s, ft/s)

Impact Force

Mass is fixed, velocity is fixed, which broken down into distance/time, both the distance and time are very, very limited. Even a doubling of the available distance will only reduce the deceleration time by very small amounts and we are exceeding the allowable load that the human brain can take by extremely large margins. What I mean by this is that while there are likely improvements to be made in helmet materials and combinations therein, the gains are likely to be very limited. Making a profound difference is going to require some very out of the box thinking.

Short of anti-gravity technology the only thing that comes to my mind is decoupled deformation of the shell. This would be where the kinetic energy from the impact is transported around the shell of the helmet to the opposite side where said energy is wasted in harmless deformation away from the head. Even something like this isn't likely to make enormous gains because the skull relative to the brain hasn't changed during a rapid deceleration.

Darth Lefty 

This is about motorcycles and not bicycles, but 11 years ago Motorcyclist Magazine, in association with David Thom and Dr. Harry Hurt (yes, his real name), did an article called "Blowing the Lid Off" where they tested a large number of helmets, and then posed some pointed questions about the Snell helmet standard of the time - both its test conditions and its thresholds for g-forces. Here's a link to the article but Googling it is actually better, you will find the Snell rebuttal and some other cool stuff. The journalist who wrote it was later fired by Motorcylist for continuing to pick at the same topic in other publications, endangering ad revenue from helmet makers. It led to revisions in several commercial and ECE standards. I think the DOT standard still hasn't changed, though. This was before MIPS really took off, so you might consider it out of date now.

Redhatter

Many thanks, I will have a look at that. It's true that time might've marched on, but it's still worth looking at as clearly they've looked at how they're modelled.

While obviously this project was prompted by a fatal single-vehicle bicycle accident, this sort of thing happens to motorcyclists too, so if there's some way I can improve things for them, then I'll look into it.

It's been an interesting discussion so far. Funnily enough, when I started this project off, I did some looking around, seems the idea of the crumple zone has been done by at least two companies:

- Zero1 | VICIS -- yes, a "football" helmet, but it demonstrates the concept. Patent document seems to be this one: https://patentscope.wipo.int/search/...d=WO2015069800
- 6D Helmets -- a lot of theirs seem to have a system similar to what I see in the Zero1.
- Bicycle Helmet Patents mentions a number of crumple-zone related patents.