Below 20 F my goose down leather mittens. (Too warm over 20 F) about 20 to about 40 F ski gloves with easy cinch wrist and cuff straps, one pull for tight or for loose. 40 F to about 50 F thin but waterproof gloves. Never need anything else. Also some of my century rides go from low 50's to low 20's. It's easy to carry one extra pair of gloves or mittens, just in case.

When one needs to take off your gloves or mittens off to do something in the cold, put them under as many top layers as you can. Against your chest. This means they will be warm enough when you put them on again. It can take a long time to re warm them in the cold. To increase heat to your hands, or any part of your body do as much hard pedaling you possibly can. Try a high gear that you can't spin, and try and spin it, 30 seconds if you can. Repeat as needed.