urbanknight

Honestly, the best practice is to evaluate each situation on its own. If the lane is wide enough to accommodate a car and a bicycle side-by-side safely (re: 3'+ between them), I usually ride the edge (which is required by law where I live). If the lane is not wide enough, I take the primary position in the middle of the lane (which is allowed by law where I live) to discourage cars from trying to squeeze through with oncoming traffic. If there is a parking lane next to me, I move out at least 3' to avoid doorings, and take the primary position if that doesn't leave enough room for a car to safely pass. Even if there is a shoulder, there could be reasons to ride in the lane (debris, parked cars, vanishing and reappearing shoulder, storm grates, etc.). Again where I live, cyclists are never obligated to ride on a shoulder, and sometimes it's unwise for visibility reasons.

There are tons of variations on that with their own nuances, and I also let the general behavior of drivers in that area to help me make my decisions. I'm also only human, so sometimes I make the wrong choice. Based on the recent close passes I have been getting around Chatsworth Lake, I need to take the primary position there more often.