Most often I don't really carry ANYTHING on my commute (Other than tools for flats, etc) so I could ride without pannier... but my grocery panniers are always on my bike anyway and they're really useful if I decide to stop or suddenly need to carry something somewhere.
I used a backpack for a while, but hated how bad I was soaked with sweat when I got anywhere.
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"There is no greater wonder than the way the face and character of a woman fit so perfectly in a man's mind, and stay there, and he could never tell you why. It just seems it was the thing he most wanted." Robert Louis Stevenson
