Wilbur Wright approached this same question in January of 1903. Up until then,
he had not formally tested various shapes for strut profiles. The struts of
the 1900 and 1901 gliders are believed to be roughly a long teardrop in
cross-section. The 1902 glider was built using the 1901's struts, so it would
be the same as well. However, after wind tunnel testing, Wilbur found that he
obtained the lowest "head resistance" or drag, with a shape that was
rectangular in section, but with 1/4-round chamfered corners. This doesn't
seem to make sense considering what we now use, but that's what he found, and
that's what's on all of the later Wright machines.

Just a little historical perspective,
Harry