Talking bout
bike safety last night with the wife, and both us agree that there should be a FLASHING red light on
the back of each and every bike that would be light sensitive to come on at dusk. This should be made as a law, with hefty fines for those who don't have them! This could save the many as the light dims at the end of the day and they are wearing
dark clothing, that blend them in with the road ahead.
The helmet? In a slight, slower accident it
could help. However, on a brutal impact where the brain is still travelling that short distance before it comes in contact with the inside of the skull? The jury is still out with me. A
race car helmet would work, but the design/weight is too much for a bike rider.
My rant for the day.
Q
I do not quibble with your "Jury is still out" because of the various types of accidents and injuries that one can suffer on a bike in so many various accidents. In the case of helmet use, I specifically address the issue of head trauma and potential neck trauma - everything below that is really not addressed by helmet usage but rather the mechanisms of what hit you / you hit, where on your body, what forces, and whether there are multiple impacts (ie being run over or hit again.
IMO, the issue with head trauma is between surviving the initial impact of head to hard surface or sudden stops. The primary purpose of helmets is to try to prevent major / significant damage to 1) superficial facial and head tissues - nose, cheeks, jaw, eyes, forehead, all areas of scalp, maybe ears. Full face helmets like used on motorbikes and racing would excel at that for low speed purposes like bicycle riding but for many, the complete facial coverage would be suffocating as would the weight of those helmets in typical bicycle riding positions. Most bike helmets can help with protecting some of the head structures that it covers but the face is left fairly uncovered so a lot of facial trauma could happen but thankfully mostly does not occur because only a small percentage of crashes are head over the bars and face plant. If you've ever seen extremity road rash (even through jerseys, light jackets, and shorts), one can appreciate what your face and head can look like if skidded across the ground unprotected. And that's for just the exposed skin on your head.
The second purpose is to protect the skull from direct and solid impact on the ground or hard object through dissipation of said impact energy on more surface or the destruction of the helmet itself to protect the skull. This is quite important in low speed impacts because skull fractures become the leading cause of more extensive brain injury - which include meningeal artery tears, meningeal tears, cerebralspinal fluid leaks, concussions, direct and countrecoup brain concussion and and contusion, and bleeding in and under various coverings of the brain and brain itself (hematomas). Diverting or dissipating or otherwise vectoring the impact forces can significantly decrease the likelihood of direct skull damage and lessen (not eliminate) the potential for direct or indirect brain injury. At least if the helmet has done its job, its hopefully prevented a major traumatic skull fracture and attendant higher risk of brain injury. Think cracked coconut shell or melon rind.
Of course, given enough force (like riding downhill at 25+ MPH, or being hit and thrown by car at similar speed) even a helmet properly placed, may not be able to protect or prevent serious head injury - but, big BUT, it give you a much better and fighting chance than without a helmet because it can give you the chance to change the vector of force (sliding, bouncing, breaking, etc.) instead of the skull/scalp making the first contact while your body is dissipating all the force and motion put into it. Bike helmets ARE for relatively low speed crashes - crashes which can and do cause significant injury if unprotected and the objects hit (road, curbs, sidewalks, immovable objects) cannot give way.
Once you exceed 25-35mph speeds, the forces are considerably higher and head injury is going specifically depend on whether the head is directly traumatized or lucks out and is deflected or rolled or otherwise relatively LESS affected - i.e. the luck of the impact and subsequent fall/contact. Motorcycle riders know this issue because of the speeds they are at and if they have to lay down a bike, they roll or slide in some semi-controlled manner if possible (of course, with full leathers also). Higher speeds (50+) on motorcycles simply must depend on avoidance because hard and sudden impacts there will bypass literally any body defenses known except for Iron Man armor (well, maybe Rhodey couldn't survive his War Machine fall?).
Motor racing helmets are primarily designed to survive the initial impacts of the head within a cockpit which itself is designed to cocoon and protect the driver as much as possible. However, the violent actions of a race car crash cannot predict nor protect against penetration or objects hitting the driver with massive forces at speed - many drivers have been killed by flying debris/shrapnel like wheels, body and chassis parts, and wings, or neck and lower skull damage by sudden impact stops that transmit into the body, neck and head (basilar skull fractures) - hence the HANS head movement restriction devices that are now used in vehicle racing that supplements the helmets. See
https://en.wikipedia.org/wiki/HANS_device. It is interesting to note, like pretty much all safety advances (seat belts, any helmets, fire suppression, HANS, roll cages, etc., even track barriers and mobile medical/surgical units), these were resisted by the drivers, teams, and even sanctioning bodies for long periods of time until enough drivers DIED, and real research put knowledge into the equations.
Of course, many cyclists will be injured or killed by accidents or collisions with motor vehicles where the injuries are bodily or neck related, areas where the helmet will have little to no protection because of the forces and impact areas of the body affected or the human body is so physically traumatized by the auto/fall that they would not survive much like being struck as a pedestrian.