I got a pair of Grip Grab Arctic shoe covers this winter and they've been a revelation, allowing me to stay on the road bike and SPD's way below freezing. Awesome, well-built product. Below 25 or so I add chemical toe-warmers between my two pairs of socks. Get the size up from your shoe size. Only time I wear non-cycling shoes now is when there's snow on the ground and I'm on the MTB.