a tri bike would work out IF the geometry weren't all wonky like modern tri bikes (72 ht / 75-76 st) tend to be. i seem to recall that some of the early (read: steel) ones had crit geometry and campy 1010s in back.

that sort of bike with SLX or OX platinum tubes, lugged, with internal routing and steep angles would be my ideal 1x9 machine.