Oh wow Dianyla, my husband and I both have those Black Diamond Guide gloves (in black) and yes they are insanely bulletproof for the very coldest conditions! Great for snowshoeing, hiking in the dead of winter, and blizzard wear!
For me they are too bulky for biking though (prolly wouldn't be biking in sub zero anyway).
My best system for biking in the cold for over an hour is to wear some thin cashmere 'ladies' fashion gloves as a fuzzy soft wool liner, then good pair of polartec-lined windstopper women's gloves, then last on top of those a pair of men's Manzella brand ski shell gloves which are quite warm, lightweight, & windstopper. This last pair is loose and slips on well over the other two gloves and is thin and flexible so that I can still work the brifters. The leather grips well on my handlebars. They are loose enough to allow another layer of air to keep my hand warm.