A female friend of mine is interested in picking up an Iro Mark V. We went to a LBS yesterday to get sized up for a Pista, but she changed her mind/it wasn't available. Regardless, they figured she would fit best on a 51. So, the Mark V's are sized 50 & 53. What size do you guys she should get?
Additionally, she's 5'5" w/ an inseam of 30.5".

I understand, that there are many more factors other than inseam and height that factor into correct bike sizing; I'm just trying to get another opinion/real-life experience.

Thanks
~ellis