I have so often ridden right beside people who are working as hard or harder as I am, are as much or more dressed, but they're shivering and turning blue and I"m not. I do tend to have more natural insulation than they do, and I want my (uninsulated :-)) ears covered oh, about at 49 degrees. 55 is my generic "want the jacket" temperature tho' that depends on sunlight and humidity, too. I was chilly today at 59 heading down to the LBS. I've never worn booties, even at 4 degrees (F). Thick socks and sneakers have always been enough for the 7-8 mile commute, and my feet get hot easily.