I am 1.80 height (about the same as you, I think) and ride a 57cm Sempre, if that helps. I did test-ride a 55, and it felt OK, but I am more at home on the 57. As far as I know the Intenso is a very similar geometry to my Sempre. In fact, they differ very little from model to model. The Sempre is a litle stiffer than the Intenso, and the Oltre stiffer still.