Race tech: Critérium du Dauphiné Libéré, June 20, 2008
German champion Fabian Wegmann of Gerolsteiner continued to test a prototype version of Shimano's upcoming Dura-Ace Di2 electronic groupset at this year's Critérium du Dauphiné Libéré although there were a few visible differences from what we last saw this past April.
Derailleur adjustments were controlled from a small box zip-tied to Wegmann's brake cables, right where the two lever cables join. Once the control box is in adjustment mode - as displayed by a red LED - the derailleurs can be micro-adjusted from the levers. This is a change from previous iterations which housed a similar switch on the front derailleur. The new position makes in-race adjustments much easier and the control box also contains a second LED to indicate battery level; the LCD panels once located on the top of the shifter bodies was gone from Wegmann's machine.
Wegmann's battery pack bore an almost identical shape to when we saw it last but the battery now has a simple clip fastening instead of its previous bolt. This makes removal and replacement far simpler and the whole unit is apparently now far more water resistant, according to Shimano. Despite the claimed battery life running into months - and with a level indicator included - the Gerolsteiner mechanics assured us that Shimano has dealt with the issue of what to do if it all goes flat: both derailleurs will simply stay where they are.
Despite being very content with his electronic shifting - and with being Shimano's guinea pig - Wegmann is expected to take both mechanical and electronic Dura-Ace setups to the upcoming Tour de France. The reason for this is simple: the current version of Shimano electronic is 110g lighter than Dura-Ace 7800, but Dura-Ace 7900 is 150g lighter.
Shimano is also developing a new version of its shallow section Dura-Ace 7850-C24 carbon wheels apparently in response to a particular UCI technical regulation. Article 1.3.018 contains a number of restrictions in regards to allowable wheels including one stating that "the section of the rim must not exceed 2.5cm on each side."
In spite of the name, the current 7850-C24 actually uses a 28mm-deep front rim (only the rear is 24mm). While the UCI will allow deeper-section wheels provided they pass a specific impact test, the 7850-C24 isn't included in the list of exceptions on the UCI web site for whatever reason (other Shimano carbon wheels are, however).
As such, Shimano has reduced the section of the front rim to 24mm as well. While the shallower depth probably isn't quite as aerodynamic as the 28mm one, it at least allows riders such as Fabian Wegmann and Grischa Niermann (Rabobank) to steer clear of the wrath of the UCI technical commissaries.