Bruno, the treble bar starts at 6.5 x 10 mm's then it's tapered, and "seasoned to taste." Recently I started drilling holes in the bar to keep the weight down.
tkoehler1, The idea behind the slanted bar is to stiffen up the treble side of the soundboard in an attempt to boost treble response. This idea has been around for quite some time, and yes, this is an option that someone could opt for or not. Not a dumb question. Glad to illuminate you on the subject.
"I have discovered (to my joy) that it is life, not death, that has no limits."- Florentino Ariza