[analog31]

>>> 3. Split it down the middle

Why split it, rather than just using the entire tubular pole? No doubt I'm overlooking an important feature. This is just for my curiosity.

[zhemao]

It allows you to flatten the bamboo out so that the weight is more distributed. Look at the pictures in the article under "Field Observation". There are simpler varieties that aren't flattened, but if you look at the poor bloke in "Problems in Current Situation", they seem to give you a massive bruise on your back.

[ChuckFrank]

Split also provides some spring to the pole.