The technology behind cycle helmets has remained unchanged for the last 30 years. HEXR has managed to create a custom mapped, 3-D printed cycle helmet which they claim is 26% safer than a standard lead. So should you consider the HEXR helmet for your next upgrade?
HEXR Helmet Review – Could Your Next Lid Be 3D Printed?
TLDR: The HEXR Helmet is a new approach to personal safety. Backed by credible research data, I’m happy to put my trust in the unit. The fit is better than most helmets, but is not quite eathshatteringly different.
Major take home is how cool the helmet is, you are NOT going to overheat in summer
TG 4/5 – Great, but expensive
Your cycle helmet is the most critical piece of cycling safety gear you’ll wear. Full stop. End of of Discussion. Previously we would make a choice as to which helmet to purchase based on looks, aerodynamics, price and that very scientifically important factor, colour. This being as the expanded polystyrene (EPS) lid that we all normally wear hasn’t changed greatly in the last few decades. But things are now changing:
We’ve had The MIPS liner added. People have designed crash sensors to go on the helmet. Now companies such as HedKayse and HEXR are looking at the very structural materials of helmets and trying to find something better than EPS.
Let’s not forget, when I say something better, the expansive polystyrene foam used for cycle helmets was originally designed as shipping packaging and is still the same material as was used in the 19670s, so we are MORE than overdue for a technical revolution in this area!
Especially as the EPS was designed specifically as a flat-pack shipping packaging, this is not as effective at absorbing an impact when it is formed into a curved surface – such as that which might be found on… I don’t know… a bike helmet!
From a crash perspective, and related to the flat pack design needs, one of the main issues with polystyrene is that this material is only able to deform optimally in one direction, and is quite difficult to control the direction of forces within a helmet during a crash – most riders tend to be busy flying through the air
As a result of this limited approach to deformity, this is one of the reasons that you frequently see helmets, post-crash, in multiple pieces. As the helmet has sustained an impact, the EPS has compressed, as designed, yet has not able to absorb the full impact VIA deformation. The problem is that the compression results in the EPS becoming denser and thus brittle, leaving the remaining force to propagate out as a crack, splitting the helmet, and allowing the force to continue on, into the rider
HEXR have not just tried to replace the standard EPS liner with a different material as HedKayse has done with the EnKayse one material, but have completely rethought how a helmet is designed to cope with an impact. I have actually recently been doing some crash testing of helmets – intentionally -I’m not saying I’ve been knocked off my bike again, so currently brimming with crash testing data, but that video is for later
After doing the testing: We dropped to 5 kg head, from the height of 1.5 m, strapped into various helmets and measuring the force transmitted, we moved to the next natural progression… and chopped the helmets up with a ban saw, as you do!
Definitely, all serious work, and not fun. Absolutely no fun at all. (And if you believe that…),
Anyway, one of the things we found when I cut open my Casco race helmet, what that Casco had approached the concept of having to manage the different crash forces by essentially having a small helmet, inside the main helmet. As we cut the unit open, part of the small helmet, which we didn’t realise was in there, flew out.
This makes quite a lot of sense from a design perspective, in terms of trying to channel the forces of an impact on the road. Appreciating the limits of the first EPS, and having a second layer to keep the impact away from the riders head.
But, you are still saddled, with the unpredictability of an EPS foam liner, just two failure chances, not one. This is something HEXR intentionally wanted to avoid when they were going through their original design plans. Below, you can see the latticework, early prototype’s
The lattice gives a good impression as to how HEXR have worked to address the issue of dissipating a crash impact. Rather than just having an EPS liner with a known level of deformity, the density, and number of connections on the latticework differs across the helmet. Meaning the bonds in the lattice will release, and crumple, differently with different impact forces, essentially, allowing the energy to be better distributed and absorbed by the material of the helmet, rather than being transmitted through the material in a less easily controlled manner
This approach to controlling multiple different forms of absorption has been enhanced and refined into the final HEXR helmet design which we have today. But over 100 different materials and configurations were assessed to get to the current helmet, it would seem that materials science really has been the key here!
As well as the material, the structure is also vital, seen here in the different sized hexagons, and variable thicknesses of hexagon walls across the HEXR helmet. HEXR describe these as “active” cells – I read that as being able collapse and deform – at any angle. Keeping in mind that EPS is designed to absorb impacts when manufactured in flat sheets these active cells can be arranged in various alignments allowing for better absorption and management of an impact than EPS.
The approach the HEXR helmet used to dissipate an impact is very clever and is much more akin to the crumple zones built into modern cars than a standard helmet. Don’t forget when a standard helmet receives an impact, it deforms the EPS in turn becoming denser before finally cracking. With the HEXR, the cells are able softens rather than becoming denser on impact to absorb more of the energy – the more energy going into the helmet, the less into your head!
Given that the are multiple different hexagons, you have many many crumple zones, with slightly different tolerances across the structure. This is a completely new way of approaching a crash helmet, whether cycling or otherwise. As the hexagonal cells deform, more cells are exposed to the impact, or recruited, spreading and absorbing the forces over a wider area than the original impact zone… without the increased density, cracking and continued transmission of the force you’d get with a normal helmet. The HEXR design approach seems to be frankly revolutionary, but we need data. Oh, they are pushing out data as fast as people will listen! Let’s take a look – even on this superficial graph you can see how the HEXR helmet is smoothing out the force, rather than letting it propogate
But that looks like internal data. Which we should STRENUOUSLY distrust. So HEXR approached Prof Rémy Willinger to help with independence testing. You may recognise his time, as he was the chap who performed the evaluation of the WAVECEL concept against MIPS, and has been instrumental in designing European helmet crash tests, focusing on multiple angles of crashes, not just a flat drop as is in the 1970s helmet crash test currently helmets are rated on. All of his previous data, and 100 articles is available online, his paper on MIPS vs WAVECEL is a very interesting, if technical read – particularly so as MIPS disagreed– you can access the PDF comparing the two here.
Currently, HEXR does not have the same comparative study, although work is ongoing with the University of Strausburg to address this. HEXR does however has a direct test of their helmet, again an independent study by Prof Willinger the paper is available here. This testing is the same as in the above WAVECEL trial and again whilst there is not a direct comparison, data from other helmets which have also been crashed were compared. Although one objection I have to the paper, is that those comparative helmets are not specifically listed, but you can find them if you dig into the ancillary documents
WAVECEL set themselves as a competitor to MIPS, as it can be integrated into an EPS liner. Now I am a big fan of MIPS. I think it’s a great idea, and I’m well documented in supporting MIPS inclusion in everything. From a medical perspective, I think the addition of a MIPS lining, bringing a reduction in rotation injuries is hugely important. I feel that diffuse axonal injury, caused by an oblique impact producing a rotational injury in the brain is, in many ways often more debilitating, with greater lasting damage than the simple direct blow to the head the most crashed cyclist suffer. If you want to read more about diffuse axonal injuries (essentially something turning your brain in your skull), I go into quite some detail on the Lumos MIPS review
In fact, I feel that MIPS is SO important, I now avoid using a helmet which doesn’t have it built-in. So naturally, when talking to HEXR, I was interested to know why they opted not to use MIPS in their helmet – as given previous MIPS data, that seemed a littlE odd
HEXR did actually discuss with MIPS at their early design stages but were not able to agree on an approach, leading HEXR To design a component to reduce rotation impacts without resorting to an internal liner which was apparently the discussion stumbling block, as a liner would have caused difficulty for HEXR custom-builds.
I do think HEXR has made the right choice here, certainly comparing to a standard helmet, there is a clear benefit in testing. But rather than listen to my opinion, have a read of Prof Willinger’s HEXR conclusion:
Under oblique impact leading to rotation around X axis and around Z axix the HEXR helmet presents exceptional protection capability with brain injury risk of respectively 16% and 24% when other helmets lead to risk typically over 25% (for XRot) respectively 50% (for YRot). This demonstrates that HEXR helmet is among the best helmets when considering the 32 shown in the present report.
Under oblique impact leading to rotation around Y axis (YRot), the HEXR helmet behave less good. Brain injury risk is about 34% when other helmets lead to a risk that is typically under 25%.
As a general conclusion, it appears that when evaluating the HEXR helmet under oblique impact and versus advanced model based brain injury criteria that consider moderate and reversible brain injury, also called commotion, the overall risk is 25%. It is recalled here that the minimum requirement suggested for future helmet standard is 80% risk of moderate brain injury.UNISTRA-HEXR – Rémy WILLINGER firstname.lastname@example.org
Expertise on Helmet Evaluation
What I infer from his conclusion is: Initially the paper appears not quite a slam dunk for HEXR Helmet – what is this area where it is inferior? If you work out what the results are, then HEXR as performed well in classic crashes – superior protection from an X rotation (forwards roll), more than double the protection in a Y rotation (pitch roll), but slightly inferior protection if there is a Z rotation (yaw roll, so spinning across your head) – where the EPS design for flat impacts finally pays off
The team say that the HEXR helmet doesn’t need a MIPS internal liner as they have solved the rotational impact issue. From these results, that would seem to be correct, however, I also wonder if the inferior result on the yaw roll may be due to the HEXR helmet rotational protection being on the outside of helmet rather than the inside?
See the shell on the outside of the HEXR Helmet is designed to detach in the case of a fall allowing the head to rotate through and reducing the translation of the force through to the brain
The rubber plug on the front of the helmet will detach on impact, then allowing the cover layer to move. Very similarly to the plugs seen holding MIPS internal layers in place internally, but perhaps meaning the yaw roll is less well turned through?
HEXR has also made the external rotational component being on the outside a marking point as well, it means that it’ll the shell is user detachable, allowing HEXR to sell you different coloured aeroshells for personalisation. Currently, you can only have the stark choice between black and white, but other colours are coming soon – I’d be more than happy to be that £30 asking price if I could get one with a Proviz reflective cover!
Well, I think that is a good point to move on to the hands on part of the HEXR helmet review
HEXR Helmet Review – Design
The Hexr Helmet is a fully UK designed helmet, and is the five-year project of a UCL and Oxford University materials scientist Jamie Cook – whose major passion at university was rowing rather than cycling – so bit of an interesting passion change! The project took off however as a result of Jamie’s love of the evolving 3D printing technologies after he realised that this new approach to engineering could not only allow unique takes on established products but also previously unrealised levels of customisation
As a result of this, on the back of each HEXR helmet is 3D printed – not etched or painted – the name of the owner. Whilst just a small feature it simultaneously highlights the individuality and the attention to detail of each HEXR
You can see there is a slight roughness to the surface of the HEXR Helmet – this is literally the polymer that the helmet is printed from. Polyamide 11 was chosen from the nearly 3000 material samples that the company looked at. Not only was it the best material for producing a 3D printed helmet, but there is also the ecological benefit compared to EPS foam, which is from crude oil, where as the HEXR is a biomaterial produced from castor oil
“Ok fine”, I’m sure you say, “It’s a custom helmet, but I’ve three different shirts, all size M and yet they are three different sizes on me, I’m not sure I want to pay £299 for a helmet where I’ve just stuck a tape measure around my head!”
Fear not, as the process of getting the HEXR Helmet customised is much more involved, if slightly daft looking. You are not going to be getting out a home measuring take, don’t worry. But you are going to wearing a beanie…
The HEXR Beanie is needed to get your hair out of the way for a 3D scan of your noggin. I had my scan done via an iPad attached to a pair of cameras – and was completely painless! HEXR is expecting this to be possible with phone smartphones soon without the additional add on
Well that was painless, and took all of about 45 secs. Painless until I got a look at my 3D constructed head. There is NO way that my nose is that big! lies!! Fake news – or should that be nose?
Once the render is then completed, HEXR will produce a custom helmet mapped to your head. The theory is that you need no boa straps, no volume adjusters, this is your helmet and will fit you like a glove. Then 5 weeks before you received your helmet, you get an email with another render, including your helmet. This is a great little bit of PR, as it does vastly more to enthuse the recipient than just saying “hey, we’ve started production of your lid!
One of the reasons that it takes so long to get your HEXR helmet is that each 3D printed helmet takes 24 hrs, in total to just print. When you compare this to EPS based helmets which are mass-produced in minutes, you can see where the money is going!
Another time-consuming step is that each HEXR comes out from the 3D printer, full of excess material, which needs to be cleaned off by hand, and then the units dyed. Yes, the Polyamide 11 which is the structure of the HEXR helmet is white. This might seen a slightly redundant step, but it allows a very easy method of seeing the damage. If you drop your helmet or have a small bump, you can’t easily tell with an EPS liner if you have impacted the structure. With the HEXR, take off the shell, and if you can see lots of white, then you know that the hexagons have been disrupted and that bump was more severe than you thought – new helmet time
As each HEXR Helmet is customised to the rider, and you are not having to deal with S, M, and L and various stock boxes. So when your unit arrives it is in a matt black, featureless box, just bearings the company logo on top. I actually like it, it gives the helmet a premium feel
Unfortunately, that premium feel eases a touch when you open the box to find the helmet is packed in with just some bubble wrap. Let’s be honest, this really doesn’t matter in the grand scheme of things, however, it does detract slightly from the experience – ok now I feel superficial, But I’m always going to be honest with these things
So what is hiding under the polythene in the box?
We’ve the helmet, a soft bag to keep the helmet in, a ratchet strap for the rear of the head (odd), a few spare parts for the straps, and an instruction booklet
There is some brand advertising on the inside of the box, so you can quote stats to your mates, or explain to your better half that “Look, this is keeping me safer, I really did need a custom 3D printed helmet!”
There is also a HEXR Helmet referral code in the box to bring the price of your riding mates customs down to £275
I was, it must be said l, really surprised to see a ratchet strap including the box. So I raised this with HEXR who said it is needed, but also not – huh, then why include it? The ratchet was apparently an afterthought, it is NOT needed for the helmet, but it was needed by the initial testers as they didn’t feel comfortable wearing the helmet without it, as putting on a helmet and screwing it tight it such a natural movement. But they did come to realise it wasn’t needed and could be discarded. This is why it isn’t attached at the start, and HEXR are now reconsidering if it should be included in the box
I do fully understand what they are saying, but I have ridden with mine attached, and I do prefer using the helmet with it, but again, this may just be the psychology that I like feeling something lower on the back of my head. Most helmets sit quite high at the back of the head, but we feel that they have a broader coverage due to this strap pressing on the base of our head giving the feeing of more coverage. When you remove the HEXR strap you do feel less covered, even though that is false. Regardless of the weird psychology, fitting the ratchet is a doddle, just push in two clips. Which does reinforce the HEXR statement it does not affect the safety
There is padding inside the box, which is applied to the inside with very small bars at the top. The padding is only there to stop your skin rubbing on the inside, it isn’t needed for the fit. As there is next to no cushioning there, it is easily removable and washable, something you don’t often see with other helmets – well not padding that will survive the wash anyway
The fit inside is very flush, and it really doesn’t impact on wearing the helmet, as the padding is also nicely ventilated. One aspect that I was very surprised about with the HEXR Helmet, is that I have been cold when wearing it. EPS is an insulator, which is why it gets so hot in summer. The HEXR is like riding around in a hairnet, the airflow is brilliant!!
At the back, we’ve one massive air vent and two little ones along with a reflective section. Given that the HEXR Helmet is quite sharply priced, it would have been nice to see the 3D printing pushed even further, and have moulding for an optional, removable, LED light
Without a shadow of a doubt, the moulding of the helmet is perfect. from the shape to the surface, to the HEXR moulding in the side
However, I was a bit surprised to see the edges on one side of the aeroshell looked a little low rent
That pretty much sums ip the design aspects of the HEXR Helmet. The HEXR looks good, and from a visual perspective looks fast, which is going to be important, as I can see this being used as a race helmet by many people
HEXR Helmet Review – Specifications
- Weight: 230-250 grams – depending on sizing
- Price: £299
Using the HEXR Helmet
So big question, what is the HEXR like to wear? Honestly, the first time you put it on, it’s a little odd. It simply fits! I know that is a daft thing to say, but there you have it. You don’t need to faff with padding or rachets, it just works
If anything I found that the helmet has a little more movement than I’ve used to… some times. I can’t put my finger on how or why. Some days it’s like a second skin, some days there is a little side to side movement. But what I can say, is that I haven’t had a helmet this easy to wear before.
If I’m lucky I get to cycle most days, even if it is only a quick spin into the office. As a result, I’ve used it in a range of weathers, and in all of them, if I’m just pootling along, I don’t get a sweaty head. It really is lovely
There is perhaps the converse now though, that being the HEXR Helmet can get rather chilly. After this picture was taken on a particularly late evening coming home from the practice I’ve decided I’m now going to keep a Buff in my bag just in case of a chilly ride. You REALLY don’t get any insulation with this lid, which means it will be an utter joy in summer
Remember during the unboxing when I mentioned there was a little bag included with the HEXR? That bag is included for more than just ensuring that you don’t get scratches on the aeroshell. It is there to keep light, UV light, off the helmet when storing – yes that is recommended in the literature in the box
A normal helmet is advised to have a life of about 5 years. This is largely an arbitrary number, chosen on the assumption of people causing integrity issues over time by dropping it on the floor etc. But if handled carefully, EPS isn’t going anywhere and doesn’t really care about sunlight. Just look at the amounts of polystyrene pollution which washes up on the beaches
HEXR states that in full sunlight the HEXR Helmet has a lifespan of 3 years, so includes the storage bag to maximise this lifespan. They do however clarify that the Polyamide II material has a 6-year life span with UV exposure, but safety is their main priority, so their comment makes sense.
Now initially it might seem a little annoying to have a proper life span on the helmet, especially at the cost, essentially of £100 every year. However, if we are trying to be ecologically more aware whilst at the same time looking towards our own safety, I don’t think this is an unreasonable balance. Some things have to change, particularly with regard to our use of plastics
HEXR Helmet Review – Conclusion
I’ve been thinking about how to conclude the HEXR Helmet review. The unit is so new, such a unique approach to a helmet, and unlike other companies, they are pushing their data out as fast as anyone can produce it for them.
Not internal data, but independent tests, already established and running on different helmets, starting in 2015, and collected and made available publicly. Other manufacturers make claims, but testing and research is more closed.
HEXR are encouraging the development of a new, standardised European helmet test, likely from Prof Willinger at the University of Strassburg. Not for them, but for everyone. You have to be very confident in your product if you are begging people to make the crash tests harder
The HEXR Helmet is expensive, there is no getting around that… but then how expensive is your brain? I have an old hack commuter that I ride, I bought it for £300, I think having a helmet that costs the same as the bike is utterly fine.
If I crash or get hit, the bike gets replaced, my bones get broken, and hopefully, I heal. If i fall from my bike and sustain a diffuse axonal brain injury. THAT. IS. GAME. OVER
Sure you likely won’t die, but life will never be the same again.
The HEXR Helmet looks good, is very comfortable, and is backed by independent data supporting its best in test safety profile. £300 to buy a 25% reduced chance of braking my brain? That’s a bargain
TG 5/5, and a Recommend.