Originally Posted by
dalava
Looking at Bianchi's geometry, I would be more concerned about the top tube being too long than seat tube length. The 59cm frame has top tube length of 57.5 which is almost 2cm longer than the CC fit calculator recommends. That means you will have to get short stem or riding stretched out. Being new to road bike and coming from upright riding position of hybrid, I think your back may not like that.
The top tube length will fit him just fine. The measurements on the "eddy fit" give him 2cm of "wiggle room" on seat height, almost half a mm on setback and over half a mm on seat to bar reach. Then there is over half a mm on stem length.
OP, when you get this bike, fitting will be simple. Set the seat height and setback. Once those are locked in where the calculator puts you, measure the "saddle/handlebar" position. I'm guessing a 100mm stem will be what you need to get the reach it recommends.