In that pic my front tire was 9psi and my rear 12psi. I'm not suggesting front derailleurs don't work or rear derailleurs for that matter. I just enjoy simple clean chain lines and I'm not finding 8spds for example any handicap at all. When I have to replace the drivetain on my LHT it will get an 8 or 9 spd setup. I'm not worried about how much it weighs now.
wow, 9 and 12, I was way off with my 40 estimate! At these pressures, the tires never feel like they are "rolling off to the side" too much in corners? Or feel "iffy" for pinch flats? To give me an idea, what sort of pressures would you run if you were going to be on really hard packed stuff (or in other words, what is the max pressure you use on them?-just curious as I find them rather intriguing and it would be fun to try a bike set up like this sometime. You know I was being silly about the tubes, makes me think of those truck tire inner tubes we used to float in on the lake as kids...
and Peterpan, my thoughts exactly (your general questioning of why)