Okay so I finally weighed my rig today. I used a digital bathroom scale with 1/10lb resolution and repeated the test multiple times and the results were identical each time. I weighed my bike with everything that is on it all the time except bottles (the cages are mounted) and myself (which I realize fluctuates). The total weight of the rig as it sits and is ridden every day for everything from commuting to local club racing is 21.6lbs.

I ride a Nashbar 105 57cm alloy frame, carbon fork, FSA Omega crankset, 105 cassette/chain/FD/RD/levers, Kalloy alloy steapost/stem/44cm bars, Fizik 3mm tape, Vuelta 37mm alloy rims, Conti Grand Sport Race 25F/28R, Fizik Aliante saddle, plastic bottle cages x2, Tektro R325 brakes with Koolstop salmons and Avid Rim Wrangler extended pad carriers on the rear, Nashbar wireless double computer, Wellgo R40? pedals (Look Delta clones).

I would like to get the total weight under 20 lbs and closer to 18 if possible, and I would like to do so as cheaply as possible. So far, I figure I can save about 100 grams on the steapost for about $50, maybe 50 grams on the pedals for $35, and over 400 grams on the wheelset for under $300. This would get me to my mark for about $500, but I wonder about other options . . .

1. Can I change other things like stem and bars, or upgrade my drivetrain (which I really want to do anyway) and save more weight for less money while improving ride quality?

2. For this kind of investment, should I consider buying a much lighter carbon frame, or maybe even selling the whole bike complete and adding in $500 to upgrade to something like the Nashbar CR5, which is full carbon, RS11 wheels, Ritchey and Prologo kit, and more important, full Ultegra?

I currently weight about 190, and I have a sprinters build. I put a lot of raw power down and my current rig doesn't flex at all, except for the crankset, but the trim adjustment on the FD is enough to counter it. I'm not willing to sacrifice handling and stiffness for weight. Is it worth going lighter on the frame, or am I gonna end up with a sloppy mess made for someone 40lbs lighter than me? If not, what's my best bang for the buck? Frame/drivetrain components/peripheral components/wheels?