Here’s the question: Is it better to carry your stuff in a bike bag on your back or a bike bag on your bike?
Carrying heavy things (or anything) on your back is certainly no fun. So I just fixed up my road bike with a rear rack and bags to carry stuff. I commuted a couple of times and, well, the jury is still out. There’s good and bad to both.
Bike bag/messenger style:
Advantages: Be at one with all your excess baggage. No effect on bike handling. Less likely to carry extra shit just because it will fit in your bag.
Disadvantages: You’re a human packhorse.
Bag loaded on rear rack:
Advantages: You’re not a human packhorse. For those who always carry a bag, as most bikers do, you might forget how nice it is not to carry anything while zooming around the city.
Disadvantages: Handling is worse. Not in a dramatic way, but if you’re riding a nice nimble road bike, it becomes more sluggish. A racing bike becomes a commuter bike. Not bad if you’re commuting. But if you like racing bikes, then your commute becomes a little less fun. There’s also the issue of what to do with the pannier when you leave your bike. The rear rack could also get stolen very easily. And the bike is a bit heavier.
Bottom line: It’s not so simple. I expected to fall in love with not having my bag on my bike. And that part is nice. But I don’t like the (admittedly minor) effect on handling. I think I may reserve the rack and bag system for when I know I’m going to have a lot of heavy things to carry a long distance (for short distance I’d just use my heavy one-speed with metal baskets).
There’s probably a simple rule of thumb here: If you want to do something right, look at those who do it for a living. Bike messengers carry things on their back and ride fixed-gears. There’s probably no better way.