And back to on-topic. I don't live car free now but did for many years, usually with a supermarket within a mile or so. Now I go to a downtown farmer's market weekly. Parking there is expensive and a hassle, especially in the spring and summer and I usually ride. 9 miles. 500' of climbing. When the bikes are dialed in, I use any of three, my workhorse winter/rain/city fix gear, my geared equivalent or my Peter Mooney. The fix gear has only LowRiders on it so two front panniers is the limit (though last Sat's trip, the bags weighed in at 33 pounds. (It's apples. pears and roots at this time of year. Easy to get a lot into small bags.) The two geared bikes have rear racks also. I run the same small Ortleibs front and rear, not liking heavy loads in back.
Ortleibs have the additional plus of the very good seals. If I shop ~10am and close the bags tightly, I can do other things leaving the bike outdoors and get home early afternoon and the veggies will still be in decent shape even on warm days. They also clean really easily so food messes are not a big deal at all. (Pour in some warm water, a little detergent, sponge a little, rinse in the bath or shower and hang upside down. Done. Bags are so watertight you can carry them over good wood floors full of soapy water.)