If its bamboo vs steel, steel has to win. In one of the articles I read, it mentioned how in many parts of Asia construction scaffoldings are typically bamboo even on some of the most modern projects. For this application I think of bamboo in the same context as carbon fiber or other hi-tech composite, but its one of natures versions. Like when Howard Hughes built the spruce goose (Hercules) aircraft out of laminated wood, it was and remains an incredibly high tech use of natural materials, light and strong, and a precurser to todays fiberglass and carbon lay-ups. Fortunately, bikes are a lot less complicated, and with materials for a frame growing in urban and rural areas all over the world, even if you did wear out a frame every few years, building a new one is no big deal and seriously cheaper than getting your hands on a steel one, especially when you have to live on only a few dollars a month. Making bamboo bike frames could also be a very easy cottage industry to get started. Heres a bamboo/carbon mtb
http://www.bmeres.com/bambooframe.htm