Bike helmets producers says that after the crash or accident you need to change your helmet even if it has no harms on the first sight. This is explained by the foam part can not carry out its functions and absorb blows properly. You must always remember that the bicycle helmet first of all is the head safety as well as the car safety bag it works only once — the main task is done, it protected your head on the highest level. If you have had your helmet hit strong it needs to be changed.