Looking at the Cervelo website, there is a figure that shows how they, Cervelo, reference their virtual top tube length. From the diagram, it appears this length is referenced from the center of the head tube horizontally back to the back of the seat tube and not to the center of the seat tube as I'm accustomed to seeing. So for those lucky enough to have carbon soloists, what are the actual center to center horizontal (virtual) top tubes lengths fro a 48 and 51 cm frame? I would guess the actual lengths are maybe a centimeter shorter than what is advertised on the website. I don't live near a Cervelo dealership so I can't confirm this.

Thanks in advance for help on this matter.

I just now see your post....

I agree that the diagram is a little odd, but what they are trying to show you is the change in length as you change the seat tube angle. The Soloist Team seatpost can be changed from a 73deg to 78deg by turning the clamp around (there's a small aluminum post that fits into the carbon body of the seatpost). This is not a feature of the Soloist Carbon, but they are using the same diagram for both models.

So, the line that appears to measure to the back of the tube is showing the seatpost angle from BB center, and the effective tt is measured from that point. Notice the other line from BB center going up to the 73deg angle, which is the center of the tube. This is the only seat angle available on the Soloist Carbon.

Hope that helps!