I now use a Lowepro bag because it is NOT a handlebar bag. It's a Orion Trekker backpack resting on a front rack with platform. I love it because the heavy photo gear sits lower than in a bar bag while being at hand and I still have lots of room in the top compartment for snacks, maps, etc. Off the bike, the backpack is much more practical than a bar bag. I use to have a bar bag and carried the Orion on the rear rack for hikes. Whenever I needed the backpack, I had to transfer the gaer from the bar bag to the backpack. Now, I just use the backpack.

Attaching the bag so it wouldn't move, keeping the straps out of the wheel and making it reasonably quick to attach/detach was difficult. I doubt Lowepro could make better attachment system than what already exist for bar bags but a better system to attach a backpack like the Orion Trekker would be great. This is my best setup so far (I'll post a better pic later):



A few points:

- The front panniers are keeping the bag front sliding right and left.
- The clip that close the bag without the need of the zipper keeps the bag attached to the rack. I've had a couple accidents with earlier setup that resulted dropping a lens on asphalt. My current setup is much safer but it could be better. I think velcro straps like trunk bags would do the trick.
- The photo compartment needs to be rainproof. Not dunkable with a bulky watertight zipper, just waterproof fabric with a good flap over a normal zipper.
- The bottom needs to be hard with generous padding. I've added a layer of closed-cell padding inside the bag.