extra stuff I forgot in previous post
I drive my minvan from my rural home to the outskirts of the city, park it, take my bike from there to work. About 15 km of cycling each way each day. I ride a fixie and am usually somewhere between 20 and 30 km/hr.
I do have a front brake, which I use, and I moved the brake handle to the right hand side so I can signal with my left hand while braking.
I wear street clothes (cut offs and T shirts) and carry work clothes in a homemeade pannier that I hang on the left side ( I figger it helps to keep the cars a little further away from me if its on the left). I wear sunglasses or clear safety glasses if its not bright out 'cause I have had aggravation with dirt/dust getting into eyes and under contacts.
I have commuted in late fall and early spring (slush and snow) and find the fixie to be great in snow, since you seem to have much more control slowing/stopping with the pedals than you do with brakes. I use cheap knobby skinny tires (700 X 30C) which work on pavement, gravel, and cut through snow to get down to pavement.
I used to wear a helmet to keep my wife happy, but I had a nasty wipe out last year (a skinnier slick front tire got caught in a crack in the road) which resulted in a fractured helmet but no fractured head. Now I am a believer in hemets.