I've thought about a fixed-gear bike and its simplicity, but only one gear seems so restrictive.  I'd heard about bikes where you had two gears, but no shifter: instead, you pedal backwards to get the second gear.  Strange but efficient and reliable.  Sounds like my style!  Recently I had a rear wheel failure and started thinking I might try such a setup but forgot what it was called.  After some mental engineering I had a method that should work, and found a forum post with my same idea of a dual-chain setup.

It turns out a French company sold a bike that does this nearly a century ago, and the setup is called retro-direct drive.  Their method is a little simpler to put together and uses a single chain.  Now this is what I want.  Most people put the lower gear in reverse for the occasional hill-climbing.  For me, I think I'd use a slightly lower gear more often pedaling forward, so it's easier to start moving.  When I have a chance to go faster for a continuous stretch, I'd pedal backward for the cruising gear.

I ended up just getting a new tire and tube, but after I move I'll convert to a retro-direct and remove the shifters.