I don't usually wear a bike helmet. Does that make me an idiot?

1) yes. It has next to no concrete demonstrated downside if you don't want to die of severe head injury excluding all other outcomes

2) yes. It alters your risk from life ending to merely disfiguring, or potentially quadriplegic, but at a significantly reduced rate compared to total risks unprotected on a bike.

3) yes. But, it won't stop other complex non head non neck related injury which can of course also be terminal, and has no strict bearing on their risk.

There is a confounding theory that wearing a helmet may make you take more risk.

There is a confounding theory that wearing a helmet makes you a target of abuse, attack and increases risk.

There are confounding stats on injury and death rates presenting at EMT and hospital which demand good statistics around increase in bike riding, age, sex, alcohol, drugs.

My personal belief is the confounding theories are bad logic to ride helmetless because they mistake second and third order effects and confuse risk and frequency against total population changes.

I live in an economy with compulsory bike helmets and I know emergency doctors none of whom seriously want this ended despite increases in survivable but horrific accidents for cyclists: prior to helmet law most of these people died.

My personal opinion is yes: you're a bloody idiot, literally and figuratively.

For this opinion you have to wear a well designed standards conforming helmet properly, with chinstrap done up and fitting. Otherwise it's performative and may be worse than useless.

I wear a helmet. My helmet of choice is protec.

https://www.nature.com/articles/s41598-022-07135-1 is well written.

I've come off my bike unexpectedly twice. One at low speed, one at higher speed (~30mph). Both were due to diesel spills on a wet road surface which were not visible. In both cases the loss of traction on a corner or lane change meant an immediate slip and contact with the road surface, and due to the momentum carrying your body forward, that does mean your head smashing into the road just after your arm causing your body to rotate on impact. I walked away with a fractured finger and a grazed chin. Without the helmet I'd have either died or had a severe head injury.

I've unfortunately known several friends and acquaintances who either died immediately or who died after coming out of comas after having accidents while not wearing a helmet. It's these events which have caused me to always wear one, and they have saved my life on a few occasions. While cars have sometimes been involved, mostly these events occurred without the involvement of any other vehicle (other than people selfishly brimming their tanks while filling up, only to have it spill out on corners). People have even got brain damage falling sideways off their bikes while stationary. Wearing a helmet, for me, has been something I will always do after seeing the consequences of not wearing one.

The countries with the most cyclists don't have a lot of helmet wearers, without any problems. If you want to wear a helmet, you should. And if you go mountain biking or racing, you definitely should. But for normal every day traffic on safe bike paths, there's no need.

Of course you could argue that if you do wear a helmet, then you're safer in case you do get an accident, but the same is true when not biking. Are you an idiot for not wearing a helmet indoors (where most accidents happen)? Are you an idiot for not wearing a helmet as a pedestrian? Are you an idiot for not constantly wearing lots of protective gear? Ultimately everything is a trade-off, and there are many reasons you might not want to wear a helmet.

I never wear a helmet when riding a bike and used to commute daily. I've never had an accident involving traffic and have come off my bike less than a handful of times commuting. It seems like the odds of me coming off my bike and hitting my head is very low.

I'm not averse to helmets I just don't think wearing one makes sense for my commute. I'd rather wear a woolen hat. I do wear a helmet when I go rock climbing and would probably wear one if I was commuting in London.

Still, I decided I should wear one. I've heard of accidents where it definitely helped, or (sadly) would probably have helped. Some friends of mine push people to wear one quite hard. At worst it is useless, at best it can save me. Better safe than sorry, blah blah blah.

Also, like lights, it might also contribute to your image of a responsible biker, and might help others on the road be nicer to you. It might inspire confidence. I do feel like this when seeing someone on a bike with lights and a helmet. Of course you need to be extra nice on the road if it is true.

Maybe wear one? You know, even if your country has a strong bike culture and good infrastructure. Enter a sport shop, buy one, tie it to your bike when not in use so you don't forget it. Done. Move on to the next problem in your life. What are you trying to achieve by not wearing one if it's not straight laziness like me?

You can still have accident with other bikers, you still have to cross roads with cars sometimes, you can still hit random stuff. Even if people are nice and behave and you are careful. Shit happens.

Do it for people who like you. You are not dumb by not wearing a helmet, but dying while a helmet could have prevented the catastrophe is dumb.

But in the counterfactual, would I die earlier from something else because I'd lack exercise from not biking enough. No.

Still, ultimately, I'm going to do it this way. I value my devil may care identity too much.

True enough, but what if the other guy is an idiot?

That's your decision. Be comfortable with that.