Neoprene handlebar covers, sometimes called pogies, are the best way to keep hands warm below 40 degrees.
Constructed of waterproof 5mm neoprene with nylon lamination inside and outside, they easily attach to and remove from from the handlebars.
Thick winter gloves intended for skiing are warm enough but too bulky to actuate the shifters and brakes on most bikes.
These are designed to be used with smaller gloves which slip inside the sleeve and still allow you to activate the brakes and shifters.
Available for use with flat or road style drop handlebars.
Sold in pairs.