Have I missed the comments on rotational mass? Saving a few grams on a tire means a whole lot more energy saved than the same savings on handle bars, because of the relative distance traveled by each. Bicycle Mechanics by Wilson at MIT talks about this, I think, as do some 80s publication like the Eddy B book. Weight is one thing, applying less energy is another. Bragging rights vs. speed. That said, I was trying to decide which sadlle/ post combo to use yesterday. Saved a half pound by using lower cost components over the NR/ Brooks combo that had been on the bike.