Originally Posted by
ridelikeaturtle
The efficacy of bicycle helmets (in the reduction of transfer of g-forces to the head) is so well-established, only a fool would argue against that. But go ahead if you like.
https://bjsm.bmj.com/content/bjsports/24/1/55.full.pdf
... and all the references listed therein.
From the cited document: "Cycle helmets that meet UK and US standards have been tested. The mechanisms of energy absorption for frontal and side impacts have been analysed. A good helmet should protect the wearer for impacts up to 15 mph into a rigid flat surface."
Further: “The conclusion is that a bicycle helmet to a recognised standard provides very valuable protection for the majority of accidents, but it cannot protect the head in a high velocity direct impact.”
The paper also mentions that the neck provides almost no stability, so even if the skull were not crushed the neck could well snap at higher loads.
Basically, if you fall over at low speed a helmet will provide some protection. If you take a hard shot, (above about 15 mph) the helmet provides No protection. Once the foam deforms more than 90 percent the shock is transmitted directly to the head and neck.
Same thing I have been saying all along. helmets are good for low-speed collisions. get slammed by a car traveling 40 mph, or ride into a parked van at 20 mph, and the helmet cannot protect the rider.