I'm not tall 5'5". and when I lay on the tank at freeway speeds, the backpack encumbers my helmet and neck (aka hard to look up). So I've found that a bike messenger bag works the best for me (timbuk2), with a chest stability strap, like a real backpack would have, the bag always stays in place. for my kawi, and just small stuff I use a tank bag.
I have cars, but I prefer to commute on a motorcycle.
Last edited by numbafree; 12-05-2012 at 08:39 PM.