I have a 5 miles commute, and I just wear what I wear to work. I'm in IT, so I tend to be able to get away with appearing less than perfectly groomed.

Shorts and a T-shirt or camp shirt in this unbelievable heat wave in the pacific northwest. High 70s is just plain unnatural, and the 80s is a sign of the Apocalypse. High 50s to low 60s is normal and good shorts weather.

Only thing bike-ish I wear is cycling shoes. I change into sandals I keep at work when I get there.