Originally Posted by tjspiel

I don't know if it were ever a tradition exactly. I would guess that the Trek FX line is more than just a carbon road bike frame with flat bars. I would bet anything that the top tubes are longer and it wouldn't surprise me at all if there are other differences in the geometry.

I've gone the other way and took a flat bar cross-country bike and put drops on it. I suppose that was the same kind of bike abuse only in reverse. It is hard to do without using a stem that makes the set up rather odd looking. Drops move you more forward than flats do. The frames have to be different to accommodate that.

Taking a road bike and putting flats on it doesn't mean you're getting a fast hybrid. You will be more upright than you would be on a flat-bar road bike from the factory. What you're really getting is a lightweight comfort bike. Notice the wide saddles that were put on the bikes along with the flat bars.