http://www.amazon.com/SISSY-BAR-BACKPACK-by-Harley-Davidson®/dp/B001JSWWTO

I was worried that the bag would feel cumbersome/distracting, but it distributes weight pretty evenly, and after a few minutes of riding with it, I totally forgot it was there. Getting it on and off is a breeze, too, even if you’re wearing an armored jacket. The shoulder straps have an easy quick release tab, and the bag just slides off. Hate to sound so much like a Harley Davidson infomercial, but it’s a pretty good product.

http://www.ems.com/product/index.jsp?productId=3662900

It fits a computer (13″), water, GPS (when removed from motorcycle and walking around), and pretty much anything else you need for a city day. I highly recommend trying it. Once you feel the difference, you can’t go back.

One thing which helps is to snug it up so that it doesn’t move around. Having a bag flapping in the wind or shifting to the side when I’m leaned over is a bit disturbing.

This is no different from a Camelbak. In the warm months I take one of these with me on any ride over an hour or three:

http://www.amazon.com/CamelBak-M-U-L-E-Hydration-System-Charcoal/dp/B00221W9JU/ref=pd_sbs_sg_6

I do have a top case and side luggage. The issue is how to carry my laptop and various papers after I get off the bike. A cheap backpack does the trick for me.

So I guess, if you have a suitcase worth of stuff, then use a suitcase…or in this case semi-permanent motorcycle luggage that you can detach and carry with you.

But if you have just a bag’s worth of stuff, laptop, papers, phone – then luggage can be a little more of a hassle for regular commuting in the city… Which is why sometimes it makes sense to take a backpack to the airport.

But if I were carrying a change of clothes and shoes, I’d certainly need more than a backpack.

Well, I wouldn’t go as far as to say I’d argue with you, but I wholeheartedly disagree. I used to use backpacks exclusively for years riding a bike and know the feeling well. I did feel the extra weight, especially when turning or cornering, and they aren’t the easiest to get on and off while wearing a riding jacket that’s already bulked up with shoulder and elbow armor with a back protector underneath it. I had to loosen the straps when taking it off and re-tighten putting it on.

Given my preference for wearing full gear on my commute to the office (armored jacket, riding pants etc.), I carry a shirt, pants — sometimes shoes — with me to work. The better solutions that do everything a backpack does are tank bags or tail bags with quick lock mounts or magnets that have a carrying handle. Some even have built in back pack straps for when you’re off the bike.

The benefits:
- No extra weight on the rider
- In hotter months, air flows freely out and over your back (a backpack is additional sweat making layer)

That’s just my opinion based on personal experience, of course, but I do believe there’s a compelling reason people would rather roll a suitcase through an airport rather than carry it on their back. To me riding with a backpack vs. the bike carrying it is the same thing.