and if not, why?

All the time. I was hit by a car on purpose, and would have cracked my head on the street had I not been wearing one. I know this because the helmet was all cracked to sh*t.

I do.

Mark

i do. just cause i never had a new helmet just 2nd hand ones that i thought were lame, but f-it, i paid for a new one, it might as well save my life so i wear it.

I do.

I used to wear a helmet but I always crashed more, maybe it's a concious thing. Wearing it makes me feel secure so my body goes more wild and vaulnerable without me thinking about it, like nothing can hurt me. Then, oh s*.
Luckily I always land on my back or hands...ouch.

Natural selection, FTW.

I do now, but I learned the hard way.

I do. Sometimes I feel like the only one under 30 though (I'm 19). I skip it if I'm just riding across campus to class or something, but I wear it when I go for real rides.

I wear mine most of the time cause there's not really any good reason not to. A helmet with good ventilation isn't all that hot and they're fairly comfortable. I guess the only negatives are helmet hair and the rank smell if you don't wash the little pads.

EDIT: and they look dorky if you care about that kind of thing.
DOUBLE EDIT: Yes, I know I'm not wearing a helmet in my avatar. I said most of the time.

I do. I hate it in the summers, but I've got no really good reason not to wear one.

I do, well most of the time, I have problems leaving it places being that I used to never wear one.

I don't, because I am still invincible.

Funny. Way back in the 80s when I was in college I rode my bike all over the East Bay, like a maniac usually, and I never had a helmet. I only bought one because I entered a triathlon and they required one.

I guess now that I have my degree, I feel like my head is worth a lot more.

I wear one when I'm on a road where cars are doubling or tripling my speed. I don't wear one in urban environments even though I should. In cities, cars are slower as well as more aware of cyclists, so I feel safer.

i'm far too valuable to risk not wearing one.

This guy.

Well, most of the time.

I don't use a helmet om my daily commute to the ER. Stupid maybe, considering the number of cracked heads I have seen. I guess I did not get into the habit, and it is uncomfortable. The resons might not be good enough, but a life of minimized risktaking is not desirable either.

Yup, always.

I had an over-loaded bag yesterday, and I couldn't wear my helmet because the materials were pushing up against the back of it. It's the first time I've been out without one (on a longer ride) in a few months, and at first it was weird, but soon I realized how much more comfortable I am without a helmet on. But if I wanted comfort, I'd get a car, and so the helmet stays.

I dont, but maybe I should. Hmmmmm

I just bought one last week....and have been riding with it since (except on my shopping/to the neighborhood cafe/<10mph bike).

I don't, and I don't wear one on my motorcycle either. I should also mention I totalled a motorcycle while wearing one and it probably saved my life. Not really sure when it will hit me I need to start wearing one.

I do. It helps tame my hair in the mornings when I wake up with "I just got rocked" hair. My neighbor rides a bike and has been in 2 accidents, one which sent him flying head first (no helmet) into a windshield of someone's car. He doesn't wear a helmet because "he doesn't ride enough" *shrug*

I've got a small dent in my forehead, and a triangle shaped scar that shows when I get too much sun from getting t-boned by a truck in 1982. No helmet then, but always now. I took getting the blacktop scrubbed out of my face with this brillo pad thing to make it a no brainer for me