We had this bike on the velodrome in Mallorca back in December for testing and I can tell you that it's fast. The seat tube and stays are interesting and the first time I saw it I really had to hand it to the team at Specialized for going so wildly off script.. the whole seat tube/BB area violates all of the visual wind tunnel rules, which certainly led to some interesting doubts/discussions with the riders as they too expect things to look a certain way!

I'll be interested to see how they choose to market the bike and these features as this will undoubtedly be the first question/rejection of the design by everybody who sees it.

The frame cut in rear end has bolts spot, any idea what it is for?

I'll guess mounting features for a fairing/spares box/etc. The silhouette shown further down the page for the geometry shows this area filled in:

I'll guess mounting features for a fairing/spares box/etc. The silhouette shown further down the page for the geometry shows this area filled in: