Honestly, I consider my three "real" (not parts) bikes to be in good working order, with solid mechanicals and rubber. Like Lizzy, I keep a small medical kit with me in my saddle bag, with a couple snickers, two tubes, a patch kit, a small pump (enough to get me rolling again) and a spoke wrench. Since one of them is a hub-shift, one is friction shift, and the other is soon to be friction shift, and everything is QR on all but the Free Spirit, I don't bring along screwdrivers or wrenches usually, because in 99% of the instances, they're just not necessary.

With bikes, I'm not too concerned. Think about it. Relatively, they're cheap. They're reliable, they don't need much maintenance, and you don't have parts moving at 4,000 RPM, so you won't have mechanical failures due to that either.

I'd be much more concerned about enough flooding to submerge the bottoms of my cars' transmissions and oil pans.