Knickers if its gonna be cold for the entire ride, knee warmers if it might warm up.
Please note The Rules:
How to Dress for Weather. If the temperature is below 60 degrees Fahrenheit, you must wear knees or better yet, full leg warmers. If you go out of the house in 50 degree weather with bare legs, it doesn’t mean you’re tough, it just means you’re an idiot. In the summer, no matter how hot it gets, you must never wear a sleeveless jersey. Tan lines are the proud mark of a real cyclist. If you must get some additional ventilation, cut a vertical line along the inside seam of your sleeve with a pair of scissors. Not only will this help you stay cool, but it says, “my sponsors give me so many jerseys, I don’t mind wrecking one.”
To look cool, if you need to keep the sweat out of your eyes, wear a cycling cap, not a sweat band or a bandana. To look Euro-cool, just don’t sweat. And please, no arm warmers with a sleeveless jersey!