New Product: 2015 Shimano XTR 11-speed
Shimano officially announced the long-anticipated release of a new 11-speed XTR mountain bike component group today in both Race and Trail tuned versions. The new XTR M9000 component group includes options for 1x, 2x and 3x front chainring combinations, a new cassette, brakes, front and rear derailleur, shifters, a chain, pedals and wheelsets.
Rhythmic, new 11-40 tooth 11-speed cassette
The new, mountain-specific 11-speed cassette is available in a single configuration Shimano calls a “rhythm step” progression of 11-13-15-17-19-21-24-27-31-35-40 tooth cogs. Depending on the size, the cogs are crafted from aluminum, titanium or steel and employ a carbon fiber gear carrier. Unlike the company’s 11-speed road cassettes, the mountain 11-speed works on existing Shimano 10-speed cassette bodies.
Shimano is putting a lot of faith in people wrapping their heads around the rhythm step concept, which essentially refers to selecting tooth counts that result in smooth groupings of gears within so-called power bands of pedaling cadence and effort that are about 30 rpms wide. Some of the gears work well for smooth pedaling—“driving gears” as Shimano calls them—while others make good climbing gears, either for steep pitches or technical ascents.
Complicit in making the system work are the front chainring tooth counts which have significantly changed from prior 2x and 3x versions to create adjacent and accessible gears within these usage bands. And while the math pencils out—and we think the logic of it will likely become intuitive on the trail—it does seem to bias the use of a front derailleur system over a 1x option.
1x, 2x and 3x chainring options
Shimano’s new crankset is modular and designed to accommodate 1x, 2x or 3x chainring configurations interchangeably. Essentially, you can go back-and-forth between the chainring configurations without buying new crank arms, though, obviously, shifter, derailleur and possibly chain changes are necessary.
Their long-awaited 1x option comes with 30-, 32-, 34- or 36-teeth, but unlike rival SRAM and other aftermarket manufacturers it does not use a narrow/wide tooth configuration. Instead, Shimano has opted for a new tooth profile that is uniformly wider and taller than on previous chainrings, and has a slightly hooked leading edge. The company claims the profile—when used with its Shadow Plus clutch derailleur—is at least as good as narrow/wide in terms of chain retention in rough terrain.
In an effort to make a more useable combination of gears, Shimano has changed their 2x and 3x tooth counts to better work with the rhythm step gearing. XTR trail uses a 36/26t combo, while XTR Race goes with 38/28t—a departure from the wider spreads of old. Shimano says the 10-tooth jumps makes for better front shifting as well as a more logical spread of gearing ratios. In 3x, Shimano goes to a 40/30/22t from a 42/32/24t combo on the old M985 set.
Cranking it up
Combining metals and carbon fiber ranks highly on the competency scale for Shimano and perhaps nowhere is it more advanced than on the company’s high-end HollowGlide chainrings which combine long-wearing titanium teeth with a lightweight carbon fiber and alloy structure.
The new chainrings mate only with the new XTR FC-M9000 Race and XTR FC-M9020 Trail Hollowtech II crank arms which have revised bolt patterns Shimano says makes for stiffer interface and more efficient power transfer. This also means old chainrings don’t work with the new crankset and vice-versa.
The Race and Trail cranksets are each tuned to their specific usage with the former being lighter and stiffer, and the latter spec’d to be a bit tougher. The Race version sports a narrow 158mm Q-factor and uses a 3D hollow bonded structure on the non-drive arm while the Trail cranks are cold forged for greater durability and have a standard 168mm Q-factor.
Back on the chain gang
More gears necessitate a narrower chain and Shimano has introduced the CN-HG900-11 to handle the duties. The chain works in all XTR chainring configurations and features the company’s HG-X11 asymmetric plate design. This design, in combination with an impregnated surface coating on rollers and inner plates called SIL-TEC, conspires to keep the moving parts smoother operating, quieter and longer lasting, according to Shimano.
Continue to Page 2 for more on Shimano’s new 11-speed XTR group and full photo gallery »
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