Well if you choose top-of-the-line components you will almost always end up at or below UCI weight (6.8kg, or 15lb).

It's almost impossible to end up with an 8kg bike or whatever. I think 6.8kg is already very very light and many people would be more than happy at that point.

Problem is a lot of times we're riding heavy frames, heavy forks and heavy wheels. All of a sudden you upgrade to a UCI illegal bike and you feel like you're in heaven.