This is a post for the self confessed geeks out there. I watched some hi-lights of Stage 13 when Haussler took an amazing win. The next day Hayden Roulston was away in the break. What struck me was that Haussler was using 7900 and Roulston was on 7800. I fired some Tweets around and to be honest we couldn't agree, so I thought I'd drop the guys at Cervelo a quick mail.
This is a question aimed mainly at your team mechanics.
Yesterday Heinrich was using 7900 Dura Ace shifters. Today Hayden was using 7800 shifters at least. What front deraileur are the team using and why are the bikes set up differently.
Ps - answer when you get a chance.
Answer on your question from Damon Rinard (Race Engineer Cervélo TestTeam):
"Like most TestTeam riders, Hayden uses Dura-Ace 7800 STI, FD (Front
Derailleur) and RD (Rear Derailleur). Heinrich prefers 7900.
Vroomen and White design engineers measured the force required to move the lever and found it higher for 7900, especially the FD, so we prefer 7800. Also the Rotor crank is the same chain ring spacing as 7800 and most 10s cranks, while 7900 has new wider spacing (approx. 1 mm)."
So what we can surmise from this is that because of the cranks and due to the lighter action many of the Cervelo Test Teams guys prefer the 7800 version of Dura Ace. Let's not forget that Haussler used to ride for Gerolsteiner, who were one of the developement Teams who worked with Shimano on DA 7900. It probably shouldn't work with the chainrings but having great mechanics on a team they can make things work even when shouldn't.