There are some advantages to commuting on a full sized bike, but they amount to nothing when rain or a flat stops you in your tracks. Take a commute from 134th Street and Broadway to 14th Street and 6th Avenue: You can easily ride down the scenic Riverside Park without worrying about taxis and traffic lights, but if a nice storm kicks up, you are forced underground. Taking a full-sized bike into New York's subway system can be an incredible hassle. A folding bike, on the other hand, is little or no problem. You can still ride a folding bike all the way downtown, or I can ride to the the subway station, fold my bike and hop on the next train. That can give you a few extra minutes to get ready in the morning and some nice exercise.