Something fast and dependable. My commuter is an 18 speed steel Fuji road bike/tank that I bought for $35 from the local police auction two years ago after my other commuter was stolen. I've put fenders on it, and use tire liners as I ride through a lot of glass on the west side of Chicago. My commute is 11 miles each way. When I get to work I get out the unscented baby wipes and deodorant. At work I leave shoes, a belt, and several pairs of pants, and carry fresh shirts back and forth in my backpack. Also in my backpack I carry two tubes, a patch kit, a pump, and a multi-tool just to be on the safe side. Commuting through the west side of Chicago is not the most scenic of commutes, but the base miles are good and it's a good way to wake up in the morning and relieve any stress after work.