Facts about helmet  

Facts about Helmet:
It should not obstruct vision.
It should not impair with hearing.
It should be light weight.
It should not cause fatigue which causes crashes.
It should not cause skin diseases.
It should not increase the probability of neck injuries.
Kinds of helmets to be used:
It should have a thick padding of thermocole- at least 20 mm- which must extend to the sides of the head. A full face helmet is safer by all means.
Components of the helmet and their roles:
The Shell: The shell of a helmet is an injection molded thermoplastic or a pressure molded thermoset that is reinforced with glass fibers or made of fiber glass.
It absorbs energy in an impact:- The shell bends when the helmet is impacted and the underlying foam deforms. At moderate speeds the shell can take one-third of the impact energy.
It distributes local forces from an impact:- Rigid objects like stone or a projecting beam can cause a skull fracture at low forces, the shell acts to distribute the force of such impact eliminating the risk of penetration.
It allows sliding on road surfaces:- The shell being rigid and having a convex shape allows the helmet to slide along a road surface without there being an excessive force.
It protects the face and temples:- Full-face helmet is beneficial in protecting the face and jaw. The chin bar of such helmets contain rigid foam to absorb energy for direct blows on the chin, prevent facial bone fractures and prevent the lower part of the forehead and temple being struck.
The foam liner: This is a molding of polystyrene beads or polyurethane foam. It provides a stopping distance for the head. The foam can compress by 90% during an impact, although it recovers partially afterwards. But this helps increase the stopping distance thus reducing the peak deceleration of the head. It also protects as much as possible of the head.
Proper strapping system: It is essential to wear a well-fitting helmet for the effective working of chinstrap system. To test if the helmet fits your head properly, tightly fasten the chinstrap and then pull helmet off forward by gripping the rear and then pulling. The strap must be threaded correctly so that the buckle locks the strap when it is pulled from the chin side. The strap must be pulled as tight as is bearable under the chin.