Hello! I'm here again asking for knowledge. I was studying different frames and came across to a somewhat cryptic data sheet.

There are two framesets in the picture, the left one is an ENE-CICLO C-2, and the other one, known as "St. Johns", is from "THE LIGHT BLUE".

The data for the Ene-Ciclo has two columns I can't understand: "F.C" and "R.C." What could those measurements be? I highlighted the more similar sizes to compare, but I'm still puzzled. Any idea?

I think is the distance from the BB. Front Center of the hub to BB and Rear Center of the hub to BB (chainstay length).

Of course! That's why the chainstay length is the same on every size: they have to use the same tires. Thank you very much!

My guess is the same as Gerry's, but about chain stay length... It doesn't have to be the same on every size frame of a given model. For example, HERE are the numbers for my Bianchi San Mateo. Chain stay length increases as the frame size goes up, differing by a centimeter between the smallest and largest frame sizes.