I finally solved this (for myself). In Canada we have a store called Marks Work Warehouse. I bought a liner glove and the thickest mitt they sell. The other day I was riding when it was -10c with the wind chill and my hands were actually sweating. I'm sure they will be fine down to -15 to -20 (coldest I would ride). I also use the combination when hiking and taking photos with my dslr - it's easy to slip off the mitt and use the liner glove to work the camera...and the liner is meant to work with mobile phones/gadgets.