The last two times I flew with a bike, I put it in a bike box with any references to anything cycling-related masked off, and with "ART WORK" written on it several times. Both airlines (one international, one domestic) charged $50 to fly a bike, but nothing for artwork. It was an SLX tubed Ciocc, with those wonderful chromed long point lugs...certainly a work of art to me!
I tossed in about 12 lbs worth of tools and spares....nobody said anything about the weight.