I read a lot about lighter frames, tires, even seat posts etc. What confuses me is that difference between a superlight and a super heavy bicycle is under 10 kilograms.

Since light bikes are very expensive and I've never had a chance to ride one for a long time, I'm curious to hear from experienced people: does it really matter, how big difference does it make for everyday riding?

I weigh some 75 kgs and often carry around 10 kgs of stuff (water, food, clothes, books etc). Does a 5 - 9 kg lighter bike really make some noticeable difference? Does it go a lot faster up hills, handle better, or is weight important for racing only?

Having switched from a mountain bike to a hybrid, I feel that speed and light ride is more about thinner tires and aerodynamics, but how does weight come into that equation?