Sorry, DBD. That bike simply cannot weigh 15 lbs. Lance's climbing bike is 15 and change!
Think about it...4-5 pound frame, 4-5 pound fork. 1.5 pounds for crank, those maxxis tires are probably in the 2 pound range each, and handle bars, stems, seat, and seatpost are probably around another pound and a half. thats 17 right there...And thats being quite liberal, not even mentioning the brake...

Nice bike though, I would mind having a bike like that...a pure basher...