check out most of the entry-level road bikes. giant ocr3, felt 90, specialized dolce, etc. if you want to make those more off-roady, thicker tires can go on them. but she'll be able to have speed without working super hard because she's sitting upright for 12 miles.
i've done my first sprint through a 1/2 IM on a giant ocr3 and profile century aero bars. not perfect, but my times have not sucked. paid $500.