Originally Posted by JonathanGennick

Honestly, I'm not sure whether there is a generally accepted standard. I like level. Trouble is, seats are shaped in ways that leave me wondering what level is. So I take my best shot at level to start with. Then I ride the bike. If I feel like my weight is falling forward, then I tilt the seat ever so slightly upward. And of course the reverse if I feel like I'm falling off the backside. Sometimes it's only a single turn of the adjusting screw that does the trick. I go for a test ride, carry a wrench, and stop as needed to adjust until the result feels good.