Another thing you are noticing is the fact that many modern frames have sloping top tubes which means you have more seat post showing than with a parallel to the ground top tube. Previous posters have covered the proper set up. FWIW I have a Redline 9.2.5 and a Giant Excursion, the frames are effectively the same size. However the Redline has a sloping top tube so it has over 9" of seat post showing, the Giant is a straight top tube and has less than 6" showing. Back in the 70's we used to consider a bike to be the correct size if you only had a fist full of seat post showing...not two or three
Aaron