Bigtallfatbloke said:Now, if thisBianchi frame at 61cm is available I might be tempted because it is a LOT cheaper than the kineses grand fondo. However looking at the Bianchi geometry chart for the via nirone alu carb it says that the 61cm top tube is 58.5cm..the same as my galaxy. The bianchi 59cm has a top tube of 57.5cm (same as the kineses grand fondo 60cm)
So I am confused. Is Bianchis sizing directly comparable? I see the imaginary level top tube line on the diagram, this makes me think it should be comparable...so why the difference in top tube length?
I think you're mixing up actual and effective/horizontal top tube lengths because the 60 Gran Fondo has a 58.2 effective/horitontal top tube, not 57.5, which means it's closer to the 58.5 effective/horizontal measurement on the 61 Bianchi and your current galaxy.
The angle of slope on a top tube will effect how long the actual top tube length is but it doesn't really give you a very good idea of physical reach which is why effective/horizontal lengths are also quoted, so bikes can be better directly compared for size irrespective of top tube angle.
For instance, two bikes with identical effective/horizontal measurements (and therefore reach to the bars) could differ in their actual top tube measurements by as much as 2-3cm due to the angle of the sloping top tube.