The bee's knees.
It's not well known, but Louis Garneau's Knee Warmers 2 are the most popular item for folks who split their time between beekeeping and road cycling. Why? Because they strike an effective balance between providing the insulation you need at the knee and limiting the amount of gear you need (though we should note that they don't protect well against knee stings).
The Knee Warmers 2 are made of Garneau's Heatmaxx fabric, a polyester and elastane blend with a brushed fleece back to retain body heat. A silicone gripper at the thigh keeps each knee warmer from sliding down and bunching at the knee, and flatlock seams ensure minimal friction against your skin. A reflective logo on the shin adds some extra visibility, and these knee warmers also have a UPF/SPF rating of 50.