I'm going to show you how to install and adjust a saddle on three of the most basic type of seat posts.
This is the first one, it requires 6 mm allen key. All you're going to do is loosen up that bolt. Sometimes with this particular type, we need to loosen it a little bit more than you think. If I were just to adjust it, then I just want to get it so that it will move, so that you're disengaging the little teeth in here. Sometimes it can jam so you have to give it a little bit of a push. Once that's free you can adjusted the nose up, down, forward, and out. Alright so if I were to completely replace this saddle, I'm just going to swing that top piece, so that I can take the saddle off. Simply put the new one on and tighten it up. I get it so that it's just kind of firm-ish and then when it's on the ground, I can sort of micro adjust it. When you're trying a new saddle, a good place to start is with it completely level and it right in the middle of the rails here, so equidistant from the two ends. Sometimes it will only go a little bit with the nose up or a little bit with the nose down. Sometimes you can't get it quite level so you have to kind of play around with it. Alright, so that's one type.
another type uses a 5 mm allen key. You just loosen that and the whole thing just swivels, so you can slide it forward and back, you can put the nose up or down.
Another really common type, uses a 4mm allen key here and here. So if you want the nose down you tighten this. If you want the nose up, then you tighten that. In order to tighten one, you've got to loosen out the other one first. So if I wanted the nose up a little bit, I would loosen off the front and then that would allow me to tighten the back and the nose will swivel up. When you tighten it up, it should be with this type especially, it should be really snug. You can strip these if you really wrench on them, so you don't want to do that, but just make sure it's its getting firm.