Sorry for the radio silence- have been busting my butt at work, trying to get a framing package out the door before I leave on vacation next week.
Chafed of Chafe City, recently posted something I thought was interesting. About the same time I was struggling with getting Gilbert's new tires on his rims, she was raging at how insanely hard it can be to change a stupid bike tire. She mentioned that it's easy enough for cars to carry a whole extra wheel with tire already mounted on it around with them at all times, so they never think about it. The mass and awkwardness of carrying a spare on a bike is obviously prohibitive.
If a bike carried around a spare wheel, it would be about as inconvenient as this car I saw this morning carrying an XXL tire around: