5°F, feels like -5°F, and I was still rockin along down the sidewalk to work. When the roads are really bad I don't like to play chicken with city traffic and buses, so I just play off-road on the messy sidewalks (there is minimal pedestrian traffic when it is this cold). I am glad my winter beater has a suspension fork, it helps glide over frozen footsteps. I got in the elevator with my bike and a woman just looked at me and the bike for a second and said, "hell of a day to be doing that!" I just smiled and said, "It's the PERFECT day, I am having a lot of fun!"