Chem. toe heat packs are the best. I haven't used them on the bike, but at work I spend some long cold days out on the boat or in the water and just wool socks and insulated boots don't usually keep my feet warm enough, but they never get cold with the heat packs. I've yet to try the sole inserts but I'm looking forward to it this winter. Only drawback is they need air/Oxygen to work properly so if you use plastic bags to keep your feet dry they probalby won't work so good. I've had trouble with them working well in waders.