I would not recommend you to get a 650c because there would be a narrow range of tires and tubes to choose from, also smaller wheels will bring your bike closer to the ground which increase the chance of pedal striking the ground when turning corner and maybe a shorter set of cranks so you won't pedal strike. 5'9" is too small for a 56/58, I'm 5'11 and I ride a 55, I've tried a 58 once, it barely fits. You should really consider to get yourself a smaller frame.