A friend of mine builds recumbent bikes from bamboo.
He gets good quality bamboo which are some 4 inches diameter, and they need to be cooked (a mix of boiling in water and baking, has to do with some chemical reactions on the bamboo starch that help to harden the fibers and prevent decomposition).
Then, after he cuts the appropriate shape, he paints/seals every surface with Araldite carbon-fiber high-hardness resin (this is not a technical description!).
The actual resin code is LY 5052, I found some info in the Araldite site, there are a lot of other resins.
The tubes are tied to one another with lots of loops made from some natural-fiber rope he uses.
The bikes ride well, he managed not to breake any one of his bikes yet (and he is not light on them). Since bamboo is a composite material, I think the ride would be similar to some composite frames, a.k.a. carbon frames.
http://ecobamboobikes.blogspot.com/ (in portuguese, some photos, google-translatable)