Originally Posted by misskaz

OP, I think you're worrying about it more than you need to. I'm 5'1" and my inseam is 28". I can ride a 46cm bike with a negative standover clearance just fine. Granted I don't have boy parts, but really it's fine. It doesn't take much tilt to the side to get clear.

As far as being wobbly when you get started, I wonder if that has more to do with gear ratio than what you are thinking is center of gravity. If you're used to a BMX with a spinny gear ratio and small wheels, I can see how a full-sized bike that maybe has too big of a gear ratio is hard to get started. It takes more effort/strength to move the pedals from a stop, which means you start out slowly, and slowness on a bike = wobbly. When I ride my geared bike I will sometimes downshift before approaching a stoplight so I'm in a smaller gear to get going again for just that reason.

Some of it will come with time and just learning bike handling on a different bike (Every time I switch from one of my bikes to another I find it takes anywhere from a few minutes to a few days to feel comfortable on that bike again.) But also consider if you are trying to push a really big gear that maybe getting/modifying a bike with fewer gear inches would help with the start/stop issue. If you're doing city riding you're not going to be needing to really open up and go super fast so you don't need a big gear anyway.