My Nokian Freds eat ice and crap traction. They simply do not slip. But I use them for ice biking in Anchorage. Literally cycling on streets covered with ice and packed snow. I have to wonder what mountain biking conditions you're going to be running into. Most off-road winter cyclists in these parts use a fatbike with wide tires for floatation. The studs sink deep into the snow to reach something they can grab onto. In deep fluffy stuff they don't work well. A fat tire will float on the snow.