babysaph

Is it true that you should stand over the bike and have about an inch or two between the top bar and your crotch?

Machka 

That's a very general rule, yes.

Have a look over this article: https://www.peterwhitecycles.com/fitting.htm

MichaelW

It is a general rule with traditional road/touring frames.
Modern compact style frames with sloping top tubes are designed with over 3" of standover clearance.

saanichbc

Supposing that the bike is a traditional road type frame where the top tube is basically on the level horizontally, yep. I like mine to settle in right up to my crotch. If that's the way it fits, I find that size right for me. The other parts of the fitting process comes by experimenting with stem length & rise, style of bars and the seat stem either set back or straight up. Othere folks like to make things more scientific than they need to be, in my opinion. But my method of fitting works for me, but may not work for the next person.