I have a cheapo laptop messenger bag and made a few mods to it. Using quick disconnect clip I can quickly strap it to my sissy bar or on my solo luggage rack. I've been using it for the past 4 years with no issues.

 

I just looked at the same thing for my laptop bag. It has both a messenger bag strap and backpack straps. It has two loop hooks both top and bottom for either straps. I'm mounting the back pack straps sideways and it fits around the sissybar and pad. I can snug them up and disconnect them quickly.

 

I think mine was $119 shipped from Surdyke. It has laptop padding and pocket, rain cover, disconnect for shoulder straps with a tuck in pocket, stands upright, accessory port for a wire, separate section for files/documents, short and mesh pockets. I think it's a great piece of heavy-duty luggage.

 

My bag has all of those features as well other than the rain cover. It has a messenger bag style strap as well if you don't use it as a backpack. Separate padded compartment, little pen holders, pockets, etc. It just wasn't made for a motorcycle and it cost around $65. Anything made for a bike costs double. Someone posted recently about pet carriers. T bags or Kury had one for around $200. It didn't look any different than the airline approved carry on that sells for around $50-75. It just has a specific strap to mount it to the luggage rack. The airline bag has all of the necessary hooks to do the same.

I'm not saying that I don't like the stuff made for bikes. There are some really nice bags out there. I wish they didn't charge double what they should. They know they got the market by the ***** because it has a specific mount.