Columbus Genius was a top of the line Nivacrom alloy product in the early
90's (introduced in '91). Wall thickness is .7/.4/.7 for top and downtubes in
"standard oversize," and either single butted .8/.6 or double butted
.75/.4/.6 seattubes. There is also an outside butted seattube available, as
well as a 33 mm O.D. downtube with .8/.5/.8 walls and a 31.7 mm O.D. seattube
with single butted .8/.5 walls.
The unusual thing about Genius is what Columbus calls Differential Shape
Butting. The headtube end butts on the top and down tubes are longer on the
top and bottom, respectively, and the BB end of the downtube and seattube
(except the D.B. seattube) have butts that are longer in the horizontal plane
than the vertical plane. The idea, as I understand it, is to remove materiel
from the less highly stressed areas of the butted portion of the tube. There
are little raised bumps inside the ends of the tubes so the builder can
orient them correctly (I scrapped a Genius downtube by assuming that the
notch on both the toptube and downtube were to be on the underside of the
tube-wrong!)I've also heard from reliable sources that some well regarded
builders (none of them Listmembers!) had downtube failures when using
Genius-has anyone else heard this?
Regards,
Wes Gadd