I convert my MTB from road/tour to winter duty every fall. Mine is all squared-away, with knobbies, gel saddle, suspension fork, etc. The only scenario that bugs me in winter is when there has been a thaw and then a freeze, with ice patches everywhere. As soon as we get at least a half-inch of snow to cover that up, I'm fine, but what gets me is when there is a spell of more than four days of cold with exposed ice. It is then that I turn to running ( seems less dangerous). Otherwise, I would tear my hair out stuck indoors.