Uhhh...I could be misreading the original post, but if what you want is a bag that will give you easy access to a camera while you're riding a bike, I'd suggest a handlebar bag. Maybe something like this:



Little bit of a pain to carry around when you're off the bike, but I'm sure you can either find one with an integrated shoulder strap or rig something up. But for convenience in grabbing something while you're riding, whether it's a camera, or a hat, or a snack, hard to beat having it right by your hands.