Originally Posted by
qcpmsame
Incorrect, the physics tells you that the energy that was absorbed by the helmet would have been transferred to the skull/brain. All the actual testing of motorcycle and bicycle helmets is to failure mode so you know how much energy can be absorbed before it breaks or energy wave transfer through the helmets shell's and inner liner's medium and go into the skull/brain.
This isn't as straightforward as you make it.
How much energy the helmet absorbed before it broke depends on the extent to which the styrofoam liner compressed before breaking. If it didn't compress at all, that indicates that the helmet fractured pretty much instantly and the helmet didn't absorb much of the impact. If it compressed a lot, fair enough the helmet absorbed some energy before it failed. But the question then moves to how relevant that was in the context of the crash.
Helmets are required to be tested to a very low standard. They are only required to withstand a simple fall onto a flat surface from seven feet at zero forward speed. The amount of energy they can absorb is very limited. Even if they work as well as they possibly can, they are massively and immediately overwhelmed by the forces involved in a collision with a motor vehicle and will make no material difference to the cyclists' safety.
This may be why helmets, despite all the anecdotal evidence such as one sees in this thread, have made no difference to the casualty statistics. They are likely to be more effective at preventing minor bumps and scrapes than at saving lives or brains, and of course minor bumps and scrapes are much less likely to be reported and recorded.