I was leaving the house this morning on bike. Temps at 21 F (-6 C). Nice sunny day, but when I looked down at the pavement, noted it was a lot darker than usual. I got off my bike and try to slide with my shoes. Seemed like a little black ice, but nothing major. I continued on slowly ( I have All Terreanasaurus knobby tires on my hybrid...).
Everything went OK, but I'm wondering what's your test for go/no-go?