You need to keep the water from evaporating against your skin and from convecting away heat and the key is to COMBINE a
completely impermeable outer layer (properly weaved nylon, neoprene, etc) to block the freezing rain WITH a separate insulating inner layer made of hydrophobic material (polyester, wool, etc) to
cope with the inevitable condensation and minor failures of the outer layer. That will stem the loss of heat and then
to increase the source heat you should also use mittens instead of gloves for improved blood circulation (because, when cycling, there's always plenty of body heat in your core...it's just that the circulation isn't good enough to distribute it to the extremities as fast as the extreme cold and evaporation is sapping it out).
I use and highly recommend these (made in the UK where rain was invented):
http://www.outdoordesigns.co.uk/prod...itmittpro.html
*Note the
taped seams which are essential to keeping the water from leaking in after long periods of saturation (that or seamless, but I haven't seen seamless mittens for sale) and also the cinch cords to close the cuff and help prevent water from running into the mitten from your arm (which will be minimal so long as you aren't wearing an impermeable outer layer on your arms/torso and you shouldn't be because your torso has plenty of body heat to compensate for the losses...only the extremities face the dilemma).