I probably commented back when this was new. I still haven't bothered to figure out why a single pannier doesn't matter to riding a bike. A bike rider keeps the center of gravity of the bike in a vertical plane with the contact point of the wheels -- on average. This has to be true, or the bike would just tip over. This must mean that a rider with a single pannier leans to compensate, but I can't tell that I'm doing that.