according to Ribble website:
EPS is a process whereby an expanded polystyrene internal mould is covered in latex. Individual strands of carbon fibre are then ‘layered up’ to an exacting specification over this internal construct. The whole mould is then heated to 130°, inflated and then cured. When the latex is removed it produces a perfectly smooth finish, with none of the excess material you tend to find on the inside of less advanced frames. But what difference does this EPS core make to the overall construction of a frame?
Unlike other methods of manufacturing, the EPS process results in a frame that exhibits zero excess carbon material on the inside of the tubing. Why should this matter we hear you ask? Well, not only is the inside of the frame completely smooth to the touch, but it also eliminates any imperfections, which in turn enhances the structural integrity of each carbon fibre to create a stronger frame.
It enables the frame to be constructed as one complete section of carbon. A monocoque frame is stronger, lighter, and stiffer than a comparable bonded frame.
It eliminates the imperfections in the carbon layup that earlier production methods were susceptible to. Zero imperfections result in exceptional strength and reliability.
