In the last 20 years I have used only carbon or fiberglass tubes,... I never thought to return to bamboo but recent experience and direct contact with kiters coming from Beijing - China has been surprising and useful also to change a bit the point of view.
BJKA (Beijing Kite Association) has been with a delegation of 4 master kiters for first time in Europe, to SPOTORNO Festival del Vento organized by 30 KITE CLUB - Liguria - Italy.
BJKA counts 700 members, 100 active kiters making beautiful small masterpiece kites; at BJKA kite Festival something like 15.000 visitor people ,... crazy numbers in a european current view
I had the chance of attending a workshop covering traditional kite construction with some specific care to bamboo:
they use bamboo of good dimension (dia 3 to 4 inches) divided in 4 or 6 sectors and seasoned more than 2 years (even 10....)
no direct sunshine, no rain
divided in small sections square - rectangular, using mostly outside surface
bending with the external surface as outer radius on a alcohol flame bamboo keeps well the shape
I feel good material for large DELTA's spreaders when length of spreader goes more than 1 meter and when the size of a commercial tube starts to be 10... 14 and more millimeters of diameter
Some pictures and beautiful kites can be seen in :http://www.ipernity.com/doc/1148945/album/969032http://www.ipernity.com/doc/1148945/44515030//in/album/969032
and near pictures
for a DELTA's spreader of course more slim bamboo stripes need to be arranged in 4 or 6 configuration as suggested in a previous post
as general remark it was a personal very positive experience the contact with very nice people that have a fully different old and rich culture a pure passion for kite, flying like birds,....
SMAC from Italy