Rounder, Smoother, Stronger Shells
Impact absorption definitely is the essential role of a helmet for protection of the wearer. In fact, the history of ARAI has been the ongoing efforts to elevate the level of its capability, and such effort of ARAI shall never stop.
Yet, it also is true the wearer of the helmet can be travelling much faster than the drop speed of the impact tests. This suggests that the real world impacts can be quite different from those at the test lab.
As the kinetic energy of a moving object increases by the square of the speed, even a street rider, travelling at the legal limit, can carry up to 12 times the impact energy the world’s most stringent standard allow. No helmet, regardless of brand, can be expected to manage such energies directly.
Regarding this crucial fact, it is important to know the impact energies the helmet needs to absorb can be dramatically reduced, if it can glance off obstacles by sliding across uneven surfaces and divert energies of the impact.
This fact reveals that the ability of a helmet to slide over uneven surfaces is another fundamental role of a helmet for real world protection.
ARAI has been observing this throughout our long history.
Experience, though decades of lessons learned in the street and on the track, continues to reinforce a simple truth that a Rounder, Smoother and Stronger Shell is better able to divert impact energy by sliding across uneven surfaces and glancing off obstacles more easily, as well as helping to minimize excess rotational forces. Thus, ARAI believes in a continuous convex curve of a minimum radius 75mm – defined by the R75 SHAPE.
The R75 concept
R75 may sound complex, but it very basic at its roots: A simple tool allows everyone to visualize and easily understand for themselves. The R75 gauge demonstrates how Arai strives to maintain the R75 radius wherever possible. Move the gauge around the shell surface, as long as the two ends of the gauge are touching the surface, the shell conforms the R75 shape concept.
R75 SHAPE is one of in-house standards ARAI enforces.
ARAI does so to offer better protection to wearers.
It’s not something most standards demand. It’s something ARAI demands.
* Arai R75 SHAPE concept does not apply to areas below test line, attachment areas of visor and ventilation ducts, or some exceptional.