Are expensive bike helmets safer?

Above the certification floor, extra money mostly buys ventilation, lower weight, and better fit systems. The one genuine safety differentiator is a rotational-impact management layer. Fit and consistent wear affect real-world outcomes more than price does.

Why it happens

Every helmet sold has to meet the same impact standard, so a budget helmet and a premium one both pass the same linear-impact test. That test is the floor, and price does not buy a higher score on it.

What price does buy that matters: a low-friction slip-plane or elastomeric suspension allowing a few millimetres of movement between head and shell. That reduces rotational acceleration, which is the mechanism most associated with brain injury and is not covered by the basic linear test.

The rest of the premium is comfort engineering — more vents without losing structural integrity, lighter shells, finer retention adjustment. Those are not safety features directly, but a helmet that is comfortable is one you actually wear and position correctly, which is not nothing.