I had 165s on my Trek 5200 wsd. When I traded it for my Kuota, the lbs owner insisted I get 170s. he said, "I think you are a power animal inside and these will help." I tried the 170s for 2 weeks and I hated them. I felt like I had to work so much harder. So, I got the 165s back. I also have an Ultegra triple. I can spin fine on them. Maybe I am a weakling, but I really hated the 170s.
I am 5' 1", inseam is about 28.5-29 (not sure anymore).