Shimano is expected to introduce two new Dura-Ace road racing component groups for 2009, one electronic and one fully mechanical. Highlights include carbon and titanium sub-components for reduced weight; improved braking and shifting, a wider choice of gearing and of course that electronic shift system.
The details of Shimano’s next generation of Dura-Ace road racing components have become one of the worst-kept secrets in the industry. Lots of seemingly accurate information has become available from industry sources. It’s safe to say that the beans have been spilled.
However, Shimano still will not officially confirm or deny anything regarding new Dura-Ace components. According to Shimano press officer Devin Walton, “We’ve always got products and prototypes that we’re working on, developing, and preparing for sale once the concepts and products have been proven. I think the prototypes that have been 'spied' at various pro events are a prime example of that development process in motion.”
Official or not, it’s common knowledge that Shimano will eventually unveil two new Dura-Ace groups for 2009. We’re still on the hunt for good close-up images, but the information is compelling enough on its own for now.
The new 7900 group will use traditional mechanical connections for its gear-shifting and replaces the current 7800 Dura-Ace. The other - Dura-Ace Di2 -
will use the electronic system Shimano has been testing.
Dura-Ace 7900 mechanical: faster and lighter, but broader appeal, too
Dura-Ace 7900 looks to be a significant step forward in performance but Shimano has also tried to increase the group’s usability for more casual riders. The mechanical version will reportedly be over 180g lighter than Dura-Ace 7800. Along with that weight loss comes improved drivetrain efficiency; faster and more robust shift performance; and a wider range of gear options than before.
More cable, please
Shift quality has always been a Shimano priority and the new 7900 group will have increased cable pull. This means that the new drivetrain should be far more tolerant of housing contamination, slight maladjustments and hanger dimension variances. However, the new shifters and rear derailleur won’t be compatible with any other 10-speed Shimano.
Even with the increased cable pull, shift lever throw is reportedly 20 percent shorter than before. Currently there’s no word on whether Shimano will include the Multi Release or Instant Release features from XTR M970 for even faster upshifts. We’d be surprised if neither showed up.
The new STI Dual Control levers will have a flatter and more hand-friendly hood shape. Carbon brake lever blades and titanium hardware will drop some weight. Adjustable lever reach will better accommodate smaller hands and a wider assortment of bar bends. The derailleur cable housing will be concealed beneath the bar tape for a cleaner appearance.
Optional equipment for the new levers includes an updated Flight Deck integrated wireless computer. In addition to the usual speed and distance functions, the new Flight Deck will add an on-board altimeter, inclinometer and heart rate monitor. For the first time, ride data will also be downloadable to a PC for later analysis.
The rear derailleur lightens up with a carbon cage while capacity on the standard cage has been increased to 28 teeth (that suggests the mid-length GS version has been deleted). The front derailleur has been retuned for even lighter shift effort and the cage profile has been designed so there is supposedly no trimming required in any gear combination. While this last feature sounds decidedly untraditional, that’s also what we all said years ago with mountain bike drivetrains. If anyone can figure this out (and unleash it upon the masses), it’s Shimano.
Drivetrain: stiffer and smoother
The new crankset will still be made of hollow-forged aluminium but stiffness is reportedly increased 20 percent. A new outer chainring design bumps rigidity up 20 percent as well. It’s not clear whether or not those two increases are additive or inclusive. For the first time in Dura-Ace history, Shimano will offer a compact version. No word yet on whether there will also be a triple-chainring version.
The new Dura-Ace 7900 chain will use a 'quick connect' link for easier maintenance as well as hollow pins and milled-out side plates for lighter weight. The new chain will also be asymmetrical for reduced chain suck and increased precision will supposedly make for a 0.6 percent increase in efficiency. We’re about as excited about the 0.6 percent as you are (ahem) but that improved efficiency does suggest a quieter running chain.
Cassette weights have dropped a bit courtesy of a new aluminium carrier. More importantly, cog ratio options have broadened to include combinations that are more useful to casual riders such as an 11-28.
We don’t have confirmation on the future of the 2008 carbon fiber crankset. Given its minimal advantage over the alloy 7900 version we’d be surprised to see it carry on another season. We have heard, however, that a BB30-compatible alloy version may be on the way though that’s strictly an unsubstantiated rumour at this point.
Refined dual-pivot architecture is alleged to improve power and modulation over current offerings and cable routing has been cleaned up a bit for reduced friction. A new pad compound is reported to decrease stopping distances substantially in both wet and dry conditions. Titanium hardware sheds a few grams.
Dura-Ace Di2 – shifting at the speed of light
Electronic shifting might seem to be more complicated just for the sake of being, but the technology does offer performance advantages practically unattainable with mechanical systems. Our experience with earlier prototypes indicates shift button throws are remarkably short and derailleur movements are much faster than spring-loaded versions.
The Dura-Ace Di2 group will not only shift faster than the current Dura-Ace group but our information suggests that it’s also over 100g lighter, even with the battery pack. We’ll see how close to reality those figures are come production. Some of the weight savings comes from the use of alternative materials, as on the mechanical version, but we suspect the bulk of the loss comes from the omission of mechanical hardware.
Neat features include optional remote shift buttons for time trial setups; a ‘crash position’ that helps shield the rear derailleur from damage during a fall; and an auto-trimming front derailleur. We’re not sure why the latter is necessary if Shimano is touting a ‘trim-free’ front derailleur on the mechanical version.
Reliability is always the big concern with electronic shifting. Mavic's two attempts at the idea, Mektronic and Zap, suffered from disastrous reliability and that colours everyone's attitude to electronic gear controls. However, it does look like Shimano has done its homework with D12. We’ve been seeing these components in the field for several years now and it seems highly unlikely that Shimano would release this sort of technology without thoroughly working out the bugs. Reliability is also likely to be Shimano’s primary reason for using a wired set-up instead of a wireless one.
But why bother with electronic at all, you ask? We posed the question to Walton a while back regarding electronic groups in general and it isn’t difficult to transfer his response to a performance-oriented system.
“The idea of operating a drivetrain electronically and using electrical actuation is one that Shimano has been engaged in for many years,” he said. “Take for example our Nexus Auto-D internal four-speed system. The idea was to create a drivetrain that had the least amount of potential issues necessitating adjustment and versatile, yet simple operation.
“Friction and cable contamination are removed by using electrical signals; precision is ensured by precise servo motor movement; adjustment and accuracy are monitored with each shift; the user interface can be operated via a simple push of a button or using an automatic mode.”
An automatic mode? Um, okay. Battery life is expected to be in the range of months for typical users although there’s no word yet on what happens if it dies out on the road.
“It will make everyone else’s road groups look like toys”
That was the comment we heard from one industry insider (who doesn’t work at Shimano) and it’ll be interesting to see if that holds true. We’ll reserve judgment until we have access to a proper test session on production gear but one thing is certain: the market is heating up yet again and we all stand to gain.