frankly, you should get a backpack, not a messenger bag. the chrome website lists some. a messenger bag is for couriers who are constantly taking their bags on and off, and thus the shoulder strap. if your commute is of any length at all then you want a bag that distributes the load equally on your back and shoulders: that's a backpack. let messengers get messenger bags. you're not a messenger, you dont' get paid to abuse your body so that you can deliver packages. you're a commuter, so treat your body to something less strenuous.

i use a MEC bookbag, i'm sure your local REI/outdoors store has similarly good bags.

sd