+2 on the Marathon Winter's. Most of my winter riding is on dry roads, but I live in an area with many natural springs which seep onto the road in colder weather. I use them so I'm not surprised by spots of ice. There is more rolling resistance, much like riding on a cinder path, just all the time. Once you get used to it though it is not a big deal. Then again, because the early darkness, I'm usually using a bottle generator as well which adds more resistance. No biggie because I ride for fitness and I just get more of it.....