Weight and stiffness.
By going to a PressFit BB30 bb shell, we were able to make the entire BB and seat tube assembly out of continuous carbon, rather than bonding and overwrapping in an aluminum BB shell. The weight savings from this, even after adding in the weight of the PF30 inserts, nets out to around 30 grams. More importantly, because we can precisely control orientation and placement of the fibers throughout the whole structure, we can perfectly tune the stiffness of the whole bb area for each different size.
As an aside, each and every tube on each size EVO is unique. There are no shared tubes size to size, which means that every different size gets its own, size-specific lay-up, again leading to perfectly tuned stiffness and ride-feel throughout the line.
BB30 is such a great system for road and mountain bikes that Cannondale invented and mastered over ten years ago! Now other manufacturers can take advantage of the benefits of stiffness, weight reduction, simplicity, etc that comes with BB30. PressFit BB30 is a new innovation that eliminates the aluminum shell that must be integrated into the bicycle’s frame for BB30 installation.
For more information about the BB30 standard, visit bb30standard.com.