There is no trick to keeping them from freezing. If water clings to the guides or between the guides and the rod shaft, you will get ice when temps are that low. One thing that helps is to keep the water from clinging, and this can be helped by carrying a tube of chapstick. With your finger, wipe off and small amount and rub it into the guides near the top and the tiptop. I have heard of people using cooking spray and I think there are commercial repellants you could use. Something tells me Loon makes something for this purpose.