We’re talking fine tuning in the context of nanoseconds here.

To wit: Reportedly, inflatable bicycle helmets made in Europe and available to riders there — but not to consumers in the United States — offer far more protection against accident-related concussions, but only if they inflate at precisely the right moment.

Which, apparently, is not uniformly the case, according to Stanford University researchers who conducted comparative testing on the inflatable helmets and the foam-based headgear worn by riders across the United States, respectively.

As for the former, notes a recent news report focusing on the study, they “are typically successful in protecting the brain from impact force, but pose risks because they can fail to deploy properly.”

And that mandates closer assessment of the “relative risk,” says a Stanford bioengineer.

That means this: If the helmet doesn’t properly deploy for a falling rider, a distinctly adverse result could issue. If it does, though, inflatable helmet technology can be as much as five times more protective against traumatic brain injury, including concussions.

Unsurprisingly, the Swedish company that makes the helmet deems it “fully tested and safe.”

American regulators can’t readily assess that claim, say study researchers, because they are behind the ball on conducting any rigorous research into the technology. The above-cited media report states that the U.S. Consumer Product Safety Commission “does not even have a testing method in place for inflatable [helmet] versions.”

That needs to change, and soon, say researchers, given the notable anti-concussion effectiveness of inflatable helmets when they work as intended.