"Tell us how you are going...
"Tell us how you are going to hit your head and we will build you the perfect helmet."
If there were a bigger mystery, a more confrontational and controversial subject or a downright dumber story for Dirt Rider to take on than this test, please let me know. Off-road motorcycle helmets have come under more and more scrutiny lately with some much publicized accidents involving high-profile athletes' head injuries and even some deaths. Serious stuff. Complicated even further by additional press containing uneducated viewpoints and nonscientific tests based solely on safe-sounding or popular opinions. But this was not good enough for us to rest our delicate brain matter on (and in). We wanted some answers. What do the helmet tests and the st ickers that are proudly displayed (or required) on the helmet mean? How do those tests equate to the way we hit our helmets on the ground? Does the material make a difference? Does the price of a helmet matter? And what is your helmet really supposed to do?
We didn't just sit at our desks and squeeze the helmets, we turned to a recognized helmet testing establishment, ACT Lab in El Segundo, California, (formerly Collision and Injury Dynamics, which did testing for Motorcyclist magazine in June 2005) and worked in conjunction with one of ACT's staff engineers on a study for a Master's Thesis in Mechanical Engineering, all just to find out how we could learn more. Currently there is no such thing as an off-road-specific helmet standard. All helmets sold in the United States must pass the DOT FMVSS 218 test if they are to be used by motorcyclists. The other popular tests you should know about are the Snell Memorial Foundation certification M2005 for some of the helmets tested and some European safety standards like ECE 22-05 and BSI 6658. There are standards specific to Japan and Australia as well. The ECE 22-05 test is different than most international standards in that it only requires a single impact per location-an approach we agree makes sense and used in our testing.
An interesting fact is that most people I know (myself included) have never had a concussion while not wearing a helmet. Sounds like I'm making an argument against them, but you couldn't be further from the truth. The reason we get concussions while wearing our brain buckets is that we put them on when we do stuff that may injure us. We are hedging a bet that if and when we have an accident, our helmet will be there to protect us.
There is a saying in the helmet design and testing world that goes, "Tell us how you are going to hit your head and we will build you the perfect helmet." That is a very important statement to remember through this entire article. We just never know the absolute answer to how we will crash, but we can make some educated predictions.
Helmet manufacturers have many theories on how to build the safest helmet, or one that will sell. Helmet tests are varied. There becomes a delicate balance between having a helmet able to manage both a routine, lower level impact and at the same time be able to deal with the possibility of a catastrophic hit. The stiffer helmets, in both shell design and internal foam, are typically better performing at the catastrophic levels, yet at the same time tend to perform worse (not poorly, just not as well) at lower and softer hits. Conversely, helmets that have softer foam and shells do a better job at the lighter impacts but their catastrophic failure will come at lower energy levels. Sounds pretty simple, right? Not so quick. When you review the results table, you'll see that none of the helmets, in any impact test, exceeded the catastrophic magic number of 300G (the G-load transferred to the head is the measurement we used, much further explanation would take at least one week of learning high-end math). This means that one could say all the helmets passed all the tests. However, most scientists believe that lower acceleration is better, so we prefer to wear a helmet that provides the lowest Gs.
"We are hedging a bet that...
"We are hedging a bet that if and when we have an accident, our helmet will be there to protect us."
Next you must consider the ways we hit our heads into the ground. Most of the time the impacts are what would fall under the very minor impact range. Since there are no large-scale studies for off-road motorcycle helmets that we could locate to determine further data, we draw heavily from our own experiences, which tend to be varied (and are not very scientific). The ASTM (American Society for Testing and Materials) Committee for sports and athletic equipment has a headgear subcommittee including a specific off-road helmet task group of which David Thom (engineer at ACT) is a member. This group has developed a protocol for off-road helmets in a quest toward an off-road standard. With further help from ACT Lab and graduate student John Prunckle, we used the ASTM Off-Road Protocol which included hitting helmets into hard-packed dirt, soft sand, a narrow metal edge, onto a tree branch and even a footpeg. There were two different velocities into dirt and sand for each helmet. Both dirt surfaces were prepped to remain consistent for each test. The helmets were hit in different locations for each test and it took two identical helmets to complete all of the impacts. All helmets were impacted in the same locations for the same hits in relation to each other. In other words, our testing was consistent and repeatable. We did have to lower our original velocity for the footpeg after it caused some catastrophic failures on initial tests. Helmets can only be asked to do so much, even when they are protecting mere test equipment.
FMVSS 218 and Snell 2005 both require two impacts per site, but ECE 22-05 only hits a helmet once per site. For our tests, we did not do any double impacts, meaning the helmets were never subjected to more than one hit in any one location. Why is that? Because we feel that a helmet is disposable and can only be asked to save your head one time; we'll show and explain why later. So you should be prepared to throw away those dollars once they have saved your head one time. Money well spent.
Participation in this test was voluntary and helmet brands were able to participate anonymously. That was because we wanted to learn something here so we needed a large sampling of helmets. We knew that the top-performing helmets would definitely reveal their identity, and those that were not pleased with the results could keep it under wraps. For our study the Vemar VRX-7 averaged out to be the best performing helmet of the ones we tested. There were also a few manufacturers which chose not to participate, citing concerns from legal standpoints, some had issues with our testing methods, and others felt that other companies might send "ringer" helmets. I discussed concerns with each company pointing out that there was no time to send in specially constructed helmets and that our test was consistent and repeatable. While every impact surface and velocity was released along with the invitation to send helmets, specific locations of the hits were never revealed. Sure it was in a way random, but isn't that the nature of how a helmet must perform in the real world? Or maybe helmets are built a certain way because their first priority is to meet certification standard(s), because they have to-or choose to.