Omg you're a BABY!!!!!!!! *pinches cheeks*

Yeah go for a 53cm. But if I recall the boys during the summer between ninth and tenth grade correctly, you might have a ridiculous growth spurt and then need a new frame...

Okay I guess now you just need to know what cog size. Your ratio will be 46:something. I feel inadequate giving advice about this. It would depending what kind of riding you do, and where.

Oh yeah and like Squirrelypoo said, 46:17 is typical and would prob work for you.