I remember hearing, years ago, that no Western mountain bike was as tough as the cheap bikes Chinese farmers rode. Having ridden (rode?) them myself, I can say they are simple, strong bikes with large enough wheels to be plenty fast enough, although a bit cumbersome on hills.
At TEDtalks, Worldbikes are promoted at being one of the few inventions that can have great benefits for the masses.
I am still on the road and uncomfortable writing long posts. i have to admit that I am linking it here so I can read it further later.