Shared between both electronic and mechanical groupsets, the crankset, cassette and chain have not gone forgotten.
Just like every other iteration, the new 9100 crankset offers an improved stiffness-to-weight ratio. A key factor in this is the enlarged crank arms and outer chainring. Additionally, Shimano’s asymmetric approach takes a further step with closely analyzed and focused load points of the four-bolt design. This comes with a seven-gram drop in weight.
The new Dura-Ace crankset focuses on asymmetrical forces
Where is this load point? With the right crank in a 3 o’clock position, it’s the chainring spider tab to the immediate top right. It’s unclear whether the actual bolt circle diameter has changed, although even if it’s the same, new and old crankarms and chainrings won’t match visually. Regardless, Shimano will offer chainrings in 50-34, 52-36, 53-39, 54-42, and 55-42T sizes. These new chainrings are said to have a new tooth profile that’s better suited to wider gear ratios.
While details were scarce, it sounds like Shimano has also adjusted its crankset chainline slightly outward in order to better serve bikes equipped with disc brakes and short chainstays. We suspect it’s a minor change given how little was mentioned of it.
Despite increasing pressure from frame manufacturers and competing brands, Shimano will stick with its tried-and-trued 24mm steel spindle axle and a choice between press-fit and threaded bottom brackets. There’s still no direct support for those using frame systems built around oversized 30mm-diameter spindles, such as BB/PF30 and BB386EVO.
Not including the bottom bracket, crankset weights are claimed at 609 (50/34T) and 621g (53/39T).
Only minor refinements for the 9100 cassettes, with the big news being a 11-30T wide range option
The cassette isn’t too different from 9000-series, although Shimano does state a new tooth profile offers faster and smoother shifts. The cassettes continue with carbon-fibre reinforced plastic and aluminium spiders. Titanium cogs continue for the five lowest gears, with steel used for the six smaller cogs.
The big story is the new 11-30T cassette. This is the largest cassette ever offered at a Dura-Ace level and features 11-12-13-14-15-17-19-21-24-27-30T sprockets.
There are no major changes to the chain, with Shimano using the already available “901” 11-speed item. Perhaps the most notable change will be a tool-free joining link, something that was announced a few months ago.
Few details have been released beyond this picture
Update (April, 2017): Read our in-depth review of the Shimano Dura-Ace R9100 pedals.
Details of the new 9100 carbon-bodied pedals are extremely scarce, with Shimano stating nothing more than, “completing the drivetrain is a new lighter Dura-Ace pedal optimized for the perfect balance of weight and rigidity.”
Looking to the single pedal photo for evidence, it is clear the metal base plate is no longer replaceable and instead only covers exact contact points. Further milling for weight reduction is seen within the pedal body, too. We suspect the SPD-SL cleat, axle design, and choice of two spindle lengths will continue with this new generation.