In recent years, research has provided alarming conclusions surrounding the causes, severity, and
long-term effects of concussions. We now know that even seemingly minor concussions ( ‘I’m fine,
I just rang my bell’ ) may have much more serious effects on the long-term health and well-being of one’s brain. It is well documented that concussions occur from impacts in the range of 60 to 169 G’s* in the adult male and may be location dependent. This value is less in women and children.
‘Low-Threshold Energy’, or low velocity impacts, is qualified for sake of reference, throughout our documentation as velocity equal to, or less than, 4m/sec (meters per second) as measured on traditional linear helmet testing equipment. A 4m/sec impact is equivalent to roughly 120 G’s being transferred to the brain in most current model Snell and ECE approved off-road helmets. That’s 100% more than the energy necessary to sustain a concussion in an adult male!
Helmets certified to both the DOT FMVSS 218 and Snell 2010 standards are very strong and have to manage linear drop test velocities of up to 7.75 m/sec to meet the standard in varying arrays of tests. For a traditionally designed helmet to perform at this level, a stiff shell and EPS combination is required. This combination adds unnecessary weight to the equation, and limits the capability of the EPS to function adequately at lower threshold energy demands. This is due in part to the higher density EPS formulation required to pass the combined standards. The alternate solution would be to have a very large helmet with a lot of soft EPS foam installed, but this solution creates obvious problems as well.
Unfortunately, EPS foam just cannot support both ends of the energy demand spectrum at the same time without increasing its thickness by significant margins and/or being formulated from softer EPS. This is why the industry has evolved to multi-density EPS liners and larger shell diameters over recent years. While this is an improvement over single density EPS foam or extra large shells, it is not the ideal solution. And none of this does anything for rotational shearing forces caused by angular accelerations due to oblique impacts.
In other words, current helmet technology and design is still seriously lacking adequate protection from lower threshold energy demands. The stiff shell and EPS is not sufficiently active inside this low-threshold energy range and has limited ability to mitigate angular acceleration. 6D’s fully-active ODS™ dual-liner suspension system, dramatically improves low-threshold energy compliance while effectively maintaining high-energy protection as well. ODS™ also adds a whole new dimension of much needed
angular acceleration management, not found in conventional helmets of today.
*American Academy of Neurology / Ellen Deibert, MD / Richard Kryscio, PhD