I am building up a Roubaix Pro frame with R11 carbon. I asked a Roubaix group on Facebook what the difference was between R11 and R10 frame, they said it was about a pound. A pound may not sound like a lot, but when you're climbing a hill, every ounce counts. A higher grade carbon is stiffer and yet more compliant than a lower grade carbon. The biggest difference you will notice with the new Roubaix is the Future Shock that has some flex just below the stem.