Fiona N
Veteran
Hotronics electronic foot heaters - absolute life savers. One ride after Christmas, it was -9C when I got home after a couple of hours and my feet were still fine. The heaters have a small element (in an insole) which is located just under the toes so it doesn't try to heat the whole foot. The batteries are rechargeable and last for several hours, depending on the output. I've damaged my toes with frostbite, mountaineering over the years, and keeping circulation in my toes is a priority to prevent further cold injury (which cold lead to amputations) so it's not just a case of being comfortable. The initial outlay for the heaters is quite high (ca. £100 or about the same as a pair of winter cycling boots) but they (or more particularly the batteries) last for years (10 and counting) so they work out pretty good value for comfortable winter cycling.