My guy insisted I get a 170 when I got my Kuota. I had only had 165s on my other bikes. One ride on the 170s told me no way. I felt like I was mashing the whole time. He thought it would give me power. I said, "You have to have power to get power."
Seriously, I am barely 5' 1" and have a 28.5 inseam. There is a reason small bikes come with small cranks.