We should be prepared for the possibility of needing lights, right? I just transfered my lights on my commuter to my Roubaix, and I found that it's so difficult to get everything set up right that if there's a chance we need lights, I intend to just ride with lights installed (sans battery pack for the front) the entire way since otherwise, I'd take way too much time installing lights if we need them.

I don't mind carrying lights all day long since without the battery pack, it's not all that heavy. But if needing lights is completely out of the question, then I might as well shed a bit of weight.