Motorcycle bags are a style of Balenciaga bags that come in several sizes and shapes. There is the medium, the office, the weekender, and a smaller size. There is also a hobo shape, and I believe that this fall a new shopper came out. These bags have tassles on the zippers...
A bunch of other bag companies have made knockoffs of the popular Balenciaga style and call their bags motorcycle bags as well...So you can get a cheaper version which has the similar style...
If anyone has better info, feel free to add...