It's a great idea, but not easy to execute. First, you will like need to adjust the distance between the rail grips so they a) match the loops in the backpack adapter, and b) distribute the load evenly between your shoulders. For this, you need a #15 star bit tool. Then, insert the the tabs in the bottom corner protectors. Do not plan on loading the pannier very full, as it will quickly become top heavy and unstable on your back. All of this is quite manageable. But when it comes time to remove the adapter from the pannier, things become quite difficult. In order to remove the clips from the bottom corner protectors, you cannot just pop them out. You must unscrew the bottom corner protectors. That requires the aforementioned #15 star tool, and also backing the nut inside the pannier with what probably a 10mm wrench (I used an adjustable wrench). It's awkward enough that I definitely will not be using the adapter again unless I need to use it for several days in a row and carrying a little micro packable daypack like a Sea to Summit isn't an option (not likely).
I have multiple bikes - with racks and without - so this allows me to use my Ortlieb bag on a rack or on my back. The product is well built and very lightweight.
