The strength of the helmet does not mean with more solid will be better, that is not for a cycling helmet, but a steel helmet! A perfect helmet is doing its best to reduce the damage when collision happens. The strength is pretty good in lower intensity collision, not easy to fracture. In the event of that a collision reached to critical value (it means that the brain has been impact strength which indicated injured degree for the normal human brain) the helmet will be easy to crackly. Depending on rupture force to breakup could able to slow down the impactive energy. Shorten the injury for the brain, also the critical value’s transformation curve is very high. It has a very important function that a good helmet could cushion the strong impact to the point. When falling down no one could promise that his head will not fall on the sharp surface, a certain point’s impactive will reach a very high degree instantly. Some certain point on the helmet starts to breakup, but during ruptured period the directionality is very important.
The helmet with poor quality usually breakup the impactive force vertical which means also can cause the brain damaged; while a perfect helmet could breakup the impactive force to both sides divergency to help decreasing the impact force and injury to the brain due to at the rear of head has a big contact area. Maybe some riders think that most of helmets are looks very similar or the same, why the prices are so different, this is because the early investment is quite large for experienced factories, mainly displays in this aspects: design with precise calculation, force scattered directivity, material and human engineering design, collision experiment and tunnel testing etc.