for year round bike commuting in a city like chicago, two bikes are better than one. sure, i could have a single jack-of-all-trades, do-everything bike, but no one bike excells at everything. lightweight fast bikes often make reliability/suitability compromises when everything is optimized for speed, and super-reliable/can-handle-all-conditions bikes often make speed compromises when everything is optimized for reliability/foul-weather suitability. therefor, i have a nice lightweight and super-fast skinny-tire road bike that is an absolute joy to ride when the weather cooperates, and then i have a IGH/disc-brake hybrid decked out with full fenders and wider tires/studded tires (depending on season) that can get me to work and back safely and reliably when the weather doesn't cooperate.

sure, the foul weather bike is a bit slower than my road bike, but when it's rainy/icy/snowy/etc. safety becomes a bigger concern for me than flat out speed.