[I]f you are going to have a bicycle for these purposes I recommend you consider one of those newer old fashioned bikes that have fatter tires and no gears/shifting or disc or hydraulic brakes. At issue is maintenance. Bent derailleurs cannot be fixed. Trust me I know.
I don’t doubt you, though I haven’t suffered a bent derailleur … yet. Still, it doesn’t take too much imagination to see how it could happen. What internal shifting hubs have you used and (do you) recommend? I have no experience with any of them, and they’re fairly spendy to be experimenting. Also, would you run only a single front sprocket, or a gang of 3 for the range they provide? Out here in SF, and at my age, I’ve come upon some hills/roads (25% – >35%) I won’t try to pedal in any gear I have. I just get off and push, or go around.
I’m always trying to improve my bike, especially from the standpoint of ruggedness/repairability. My current bike is a 21 speed thrift shop special, bought years ago at a thrift shop for $17.99. I’ve put about $150 into it, over the years, adding things like lights, fenders, a rack, fold-out panniers, mostly at thrift shop/swap meet prices. It serves me to run errands of ~8 miles or less, and I haven’t tried to ride home with more than about 35 lbs of groceries.
Since I’ll be moving out of SF, into generally flatter territory, I bought a kid carrier trailer to convert into a more generalized load hauler. But for all of that, I figure that for a wheeled, and human-powered GOOD solution for a no fuel/roads blocked situation, something like a Pack Wheel or a Honey Badger Wheel might be the most reliable, albeit slowest, kind of transport, for those of us who lack a stable: I know a wheel can carry ~5x more than I can on my back, and at less “cost” to my knees.