Helmets (including motorbike helmets) are designed to protect you from a vertical fall of about 2 meters and hitting your head at that speed. If you have a collision at 50km/h, chances are you'll be hitting the ground from a height similar to that.
I don't know how many such collisions you've been in, but I've been in about 6 motorbike accidents of fairly light severity, including hitting a car at about 50km/h. I bounced off the front of that car and landed head-first on the road. But I had no injuries at all - in large part because I was wearing a helmet.
That said, I'm not in favour of making bicycle helmets mandatory, and I think cyclists should be allowed to use the pavement for safety, as long as they are courteous and don't go too fast (no more than 10km/h or so) when close to pedestrians.
Motorbike helmets are in no way comparable to bicycle helmets. Bicycle helmets have to be very light due to the physical activity exerted by their wearers.
Another thing you'll rarely hear bicycle advocates say is that cycling on the pavement is safer. It most definitely is not, due to the speed difference between pedestrians and cyclists. This is not only dangerous to pedestrians: drivers aren't used to checking for fast moving objects on the pavement. Worse, pavements are rarely constructed with good vehicle visibility in mind. It's also hard to figure out which rules apply (pedestrian or road?), unlike when everyone is sharing the lane.
I qualified my support for riding on the pavement with speed differentials. There's little doubt in my mind that the lower overall risk in many junctions comes from riders+pedestrians than riders+vehicles, especially turning trucks.
And motorbike helmets are actually very similar to cycle helmets under the shell. Biggest differences are abrasion resistance from the shell and more coverage on average, but 1/2 helmets - brain buckets - are very very similar. Indeed I see a certain percentage of London cyclists wearing helmets that would be legal on motorbikes in US states with mandatory laws.
Big difference with motorbike helmets: those are integral helmets, protecting your entire head. Cycle helmets only help against direct hits on the top of your head. Crashing head-first into a car or tree (or getting a tree branch on your head).
German consumer organization tests showed that lots (60% or so) of the helmets for sale in Germany didn't even meet the head-on-collision tests as the testing isn't done by an official institute...
Wearing a cycling helmet makes sense when you've got a good chance of hitting something straight on. Like mountainbiking and hitting a tree or speed cycling at 50km/h, bend over your handlebars.
Kids? Regular cyclists? Mum with groceries? No way. Or at least: other things are more effective. Like wearing a cycling helmet as a pedestrian (who apparently hit things with their head more often!).
I mean, I am not against helmets if it makes you or anyone else feel safer when biking or cycling, but making it mandatory is stupid. It is up to everyone to take their own responsibility and assume the consequences of their actions. I am appalled that in a country like the US which WAS known to value individual responsibility it has become mandatory to wear helmets when cycling.
It is up to everyone to take their own responsibility and assume the consequences of their actions. [..] I am appalled that in a country like the US which WAS known to value individual responsibility it has become mandatory to wear helmets when cycling.
Though it's hardly a new development. Seat belts have been mandatory for decades. People complain about safety restrictions like these at first but seat belt laws have been around long enough to reduce the complaints to a mere mumble. So may it happen with helmet laws.
I don't really get what people have against seat-belts.
Apart from "Nobody is going to tell me what I must do in MY car!" and some people thinking that being tossed out of your car is actually preferable scenario in most accidents.
I think there's too little data about road accidents publicly available. I think all documentation from police investigations of road accidents should be anonymized and made public after some time.
One important distinction here is that the health benefits from cycling, even without a helmet, outweigh the dangers by a factor between 7-1 and 20-1, depending on the study.
Any policy which reduces the number of people who would otherwise choose to bicycle is de facto worse for people's health. If mandatory helmet laws decreases the number of bike trips by even one, it's a net loss.
Is it really? In all the states of the US? Maybe the reason is to discourage people from cycling?
I use a bicycle to commute to work every day. I think, I really should get a helmet. But I do not think they should be mandatory. I have been run over (more like bumped into) by a car more than once. But I was lucky and had no injuries at all. With my motorcycle it is a whole different story I had two real accidents and thanks to my helmet I am still able to write this.
I don't know how many such collisions you've been in, but I've been in about 6 motorbike accidents of fairly light severity, including hitting a car at about 50km/h. I bounced off the front of that car and landed head-first on the road. But I had no injuries at all - in large part because I was wearing a helmet.
That said, I'm not in favour of making bicycle helmets mandatory, and I think cyclists should be allowed to use the pavement for safety, as long as they are courteous and don't go too fast (no more than 10km/h or so) when close to pedestrians.