n=1 here, but I did have an issue when I tried going shorter. I had a coach who wanted me to switch from 172.5 to 170 for a quicker spin with my shorter legs (I'm 5'7"). On the flats it was great and felt really comfortable. As soon as I started climbing, I struggled significantly. I thought it was in my head because it's only a 2.5mm change but when went back to 172.5 everything was back to my normal level of suckage but not more. I tried to switch 3 times and the same result each time.