 Electric scooters, rollerblades, skateboards and bikes, they are all great fun and much better than walking. Unfortunately though, when they go wrong, they can be head tracking activities. And in the age-old battle between skulls versus ground, the helmet is your number one tool. A lot of science has gone into the construction of bike helmets. The hard outer shell spreads the force of impact over a larger area of your skull, effectively to stop the skull from splitting. When your head is hit, the force of the collision can cause your brain to hit the inside of your skull. It can actually get damaged from the inside even if the skull isn't split. The inside soft part of a helmet absorbs the energy of the collision. This minimizes the amount your brain has shaken up inside your head. Without it though.