To be clear - any cyclist crazy enough to ride a bicycle on the same road as cars definitely needs all the protection they can get, I think that goes without saying. But now you've moved from the "extraordinary low risk of accident" that comes from cycling to the "Probably one of the most dangerous things I can do" risk factor.

And, pretty much 100% of the time I go snowboarding, I wear a helmet.

What I'm trying to surface (apparently poorly) is that life, to some degree, is about managing risks. And we often respond carte blanche scenarios with exactly the same response, regardless of whether it's proportionally required.

Cycling - on road, moving fast, around anything else moving fast, at all treacherous conditions - sure, yes wear a helmet. But, casual cycling on a nice day, protected path - probably not required.

Another area of proportional risk response - portable devices on planes. At one time, end of the world if you had one on during takeout (seriously, other passengers would freak out if they thought yours was on) - and then, all of a sudden - every airport/airline in the United States lets you read your kindle, play games on your phone. People realized their responses were not proportionate to the risk.

Yours are anecdotal evidence of an extremely low risk. There are some bike accidents, which are already rare; Very few involve the head; and even fewer would be saved by a helmet. Whereas, requiring a helmet is a sufficient disincentive to biking that studies have shown that it increases the number of deaths in countries that made it mandatory, by making people drive instead and later die from cardiac diseases and obesity.

So yes you should wear a helmet while biking, but we should not make it mandatory.

In other counter-intuitive statistics about biking, passing at the red light is good for you.