[kolektiv]

Yes, madness. Given expected likelihood/severity of potential accidents, one seems more worthwhile than the other. In situations where the risks are raised for some reason, you will find that people do wear helmets. I will never, for example, do 100mph in a kart without a helmet (plus various other safety additions).

[panglott]

How is a 10 mph bike ride around the block even remotely comparable to karting at 100-mph?

[kolektiv]

I'm not saying they're the same thing - I'm pointing out that as risk increases, you add safety features. Drivers in certain situations (racing, for example) do wear helmets, as the risk is now judged to be sufficient. A 10mph ride around the block may well be safe - but the 10mph part isn't so relevant - it's the idiot in a car doing 60mph who doesn't look for cyclists that is probably the significant part of the risk. So...

[panglott]

A bike helmet is not designed to protect your head if you are hit by a car at 60 mph.

The best way to protect yourself for the 60-mph-auto-collision is to not get hit by a car at 60 mph.