Quote Originally Posted by ehirsch83 View Post
The real thing to think of is the drop from where you are in the saddle to the bars- how did that feel.

They stock them with a 90cm stem normally- you can go up to a 100 or 110 or even a 120 if the drop felt really good.(I ride an 80 stem, so just know there are little things you can tweak to make the bike fit correctly)

If the 51 left you feeling too upright due to a lack of drop, then I would go with the 48 and put on a longer stem but if your drop on the 51 felt good and comfortable -then you are good to go.
Shops often build up bikes--at least women's bikes--with a riser stem in the "up" position. Turning it over so that it slopes downward can also provide a bit more drop if that's what you're after. Otherwise, I wouldn't get too fixated on standover. Again, so long as you can straddle the bike, you should be fine. SO is a bigger concern with mountain bikes and, even then, some people will tell you that it's an overemphasized metric for fit.