dont mind the questions at all. looks like bamboo bike building is the new thing, this thread could be a good resource for many.
i used a short piece of steel tube inside the seattube too. cant really see how else you would do it, i dont think the bamboo holds up to well to internal pressures like that, it would probably crack...
my next frame is going to bee 100% iron bamboo, so i will see how it compares to the first one in terms of stiffness. the first one is actually plenty stiff, but i havent taken it to the track for all out sprinting yet...
whats a punji stick?