As said above, 44x12 gets you to 29mph at a 100rpm cadence. If you can actually maintain that for more than 200 yards, then I imagine there are more than a few race teams that would be interested in signing you.

Bigger gears don't necessarily get you any more speed. It's the speed at which you turn those gears that gets you the speed. Also, turning big gears at anything approaching a fast cadence tends to put the "burn" in most people's legs.

For reference, a 44x12 is slightly smaller than a 53x14, which is a gear most mortals use only when descending, winding up a sprint, or when they have a tailwind.