ok, i realize there have been many threads on this, but because i do a hell of a lot of biking, i have some specific questions to ask: 1.Are the messenger bags comfortable to wear while riding for long periods of time? I was maybe thinkging Timbuk2 2. Are messenger bags sturdy when your biking? I'm just worried about the one strap..... i would hate for it to slide down my arm, or swing off my back in the middle of an intersection. 3. Should i just buy a nice sleeve for the laptop, and put it in my old backpack? I'm going to get a 15inch pb, and i am going to commute from my place to university. Thanks for your help guys .