What is one of the functions of the outer shell of a helmet?

The outer shell of a helmet plays a crucial role in protecting the rider, and one of its primary functions is to keep objects from reaching the head. This hard outer layer serves as the first line of defense against impacts and debris that could pose a danger while riding.

In addition to this protective aspect, the shell is typically made from materials designed to absorb and distribute the force of impacts, reducing the risk of injury during a collision. By preventing foreign objects and forces from making contact with the rider’s head, the outer shell contributes significantly to overall safety.

Other functions, while important, do not directly relate to the fundamental protective purpose of the helmet's outer shell. For instance, enhancing visibility in traffic or providing comfort and air circulation pertains more to design features rather than the primary safety function of the shell itself.