Here are some pictures and first impressions of the Ortlieb Flight backpack (rucksack). I had trouble finding any personal opinions of this bag when I was trying to decide on one, so I thought it would be nice to give mine.
Ortlieb is a well-known German company that manufactures high quality waterproof / weatherproof products such as bike panniers, backpacks, dry bags, camera cases, and various other bags and storage equipment. The Ortlieb Flight is a waterproof backpack that is designed to on and off the bike comfortably. There are two different sizes a 22 L and a 27 L bag. I have the 27 L. Some of it's features are a helmet holder, hydration bladder opening, suspended mesh back, and waterproof tizip zippers.
The main reasons I chose this bag over others is becasue I wanted a bag that was waterproof for commuting, more comfortable than a messenger bag, and it has the mesh back which will keep me cooler and less sweaty in warm weather. Some of the other backpacks I considered were the Deuter Trans Alpine 30 and a Freight Baggage backpack. While this was definitrely not the cheapest of those (that would be the Deuter Trans Alpine at $120, both the Freight and Ortlieb set you back about $200), it had all the features I wanted.
Immediately after opening the package with the bag in it, I took everything out of my Chrome Metropolis and proceeded to stuff it into the Ortlieb. The Ortlieb is smaller, but it's not considerably smaller. I like the fact that it has a large front pocket too. I'll keep tools in there.
I went around the block with the bag loaded up. It felt comfortable, but I'll reserve judgement until I've had more time with it. I'll post more pictures and impressions after using the bag more.
I'm a little over 5'10" (about 179cm), so this should give you an idea of how large the bag is. The side pockets are made of neoprene and the Kryptonite Mini just fits. I believe they are intended for water bottles.
The front view.
Here you can see the suspension system holding the bag away from my back. Most of the weight is on the bottom (lumbar) section of the bag and my shoulders when I am standing up. It is more evenly distributed across my back when on the bike. Note the chest strap can be moved up or down.
A closer view of the chest strap. The left side is bunched up a little because the bottom strap is elastic, so it has some give while you're wearing it. The top strap is there to reinforce the elastic strap, and it is the same nylon material as the strap on the right side.
The front pocket filled with some tire levers, Topeak Road Morph, Clif Bar, tube, 15mm wrench, and a Rudy Project sunglass case.
The main compartment has a box of Cheese Nips, some Q-tips, a large shampoo bottle, two bottles of lotion, a notebook, folder, long-sleeve shirt, and various other small items inside. Sorry, I don't have any large containers of alcohol to stuff in it at the moment. The total volume of the bag is 27 liters, 7.59 adorable kittens, or 1648 cubic inches.
This is a closeup of the main compartment TiZip zippers that keep the bag totally weatherproof.
If you have any questions or picture requests, I'll be happy to oblige.
I made my purchase from the online retailer wallbike.com. They have excellent customer service, and I highly recommend them.
Ortlieb Flight product page