Mountain Gear

Tech FAQ: XTR, Philosophy and Zinn

Tech guru Lennard Zinn says that perhaps what's not said about Shimano XTR philosophy is that there clearly has been a fundamental shift about what the venerable XTR group actually symbolizes.

Much has been said about the details of Shimano’s new 10-speed XTR group, and, indeed, there are lots of important details (click through the photo gallery for details on each item). However, sometimes the forest gets lost for the trees, and there is more to say about the forest — Shimano’s fundamental philosophy with XTR.

shimano_2011xtr_17Obviously, Shimano is intent on not getting rolled over by the SRAM juggernaut that relentlessly builds momentum, and that company’s “2X10” mountain bike drivetrain offerings have created quite a bit of buzz. Dyna-Sys, Shimano’s new 10-speed mountain-bike drivetrain platform, was created in response to 2X10, but it was dribbled out at Sea Otter (always SRAM’s party) as tweaks to existing XT and SLX groups, rather than as completely new groups. Shimano came off as looking resistant to 2X10 and simply adding more range to a triple. Consequently, Dyna-Sys perhaps has only been viewed as a 3X10 drivetrain that now gets a 2X10 option with the introduction of 2011 XTR. With a booth at Interbike showing cutaways of components cast in clear plastic, clear versions of working parts, and touchable, usable components on bikes, Shimano seemed to be emphasizing just the details.

However, its marketing force was attempting to go beyond the fine details to the bigger picture.

“2X10 is just a gear option,” says Shimano’s Devin Walton, “whereas Dyna-Sys is a complete drivetrain engineering philosophy, and there are gear options within it.”

Among the efficiency principles of Dyna-Sys are reduced chain tension with larger chainrings and fewer shifts to get the gear you want. The “Inherently Efficient” video on Shimano’s site attempts to illustrate how the older system could require a triple shift in order to attain a desired gear, whereas only a single shift accomplishes almost the same thing with the wider-spaced cog-diameter range in the rear and narrower-spaced chainring-diameter range in the front of a Dyna-Sys triple drivetrain.

Something that is perhaps not said about XTR philosophy is that there clearly has been a fundamental philosophical shift about what XTR actually symbolizes. When XTR was introduced in 1991, Shimano had one mountain bike group, namely Deore XT, and it had few rivals. There was competition in mountain bike groups from SunTour at the time (XTR pretty much marked the end of that) and from little else.

The “R” in XTR denoted “racing,” and mountain bike racing at the time, whether it was cross-country or downhill, was all done on the same (hardtail) bike. The look of the group was also unique; its jewel-like appearance was gorgeous, set it dramatically apart from all other mountain bike parts and is timeless even now.

Fast-forward to 2011, and while XTR’s appearance is again striking and jewel-like it is clear that the “R” now no longer just means “racing.” Yes, XTR remains Shimano’s best and lightest group, and the superlight group options are designed for cross-country racing, while the beefier group options could be applicable to downhill. But the emphasis is instead on versatility. XTR parts have long been spec’d on more gravity-oriented bikes than XC rigs, but now Shimano makes group options specific for trail riding, without racing even entering the picture.

Heavier-duty brakes with higher cooling capacity and better modulation, triple crank options, through-axle options front and rear, larger pedals and separate shifter band clamps work great on bikes with a lot more travel than three inches.

Versatility could even include changing the intent of a given bike. The switch on the front shifter to change it from a triple shifter to a double shifter is a very cool option, as is the ability to run the triple crank as a double (only the 38 X 26 gear combination is allowed with this setup, though; the crank is different, with a narrower Q-factor, for the 40-28, 42-30 and 44-30 double options).

Maybe the “R” now just means “riding.”

Readers can send brief technical questions directly to Lennard Zinn.

Technical writer Lennard Zinn is a frame builder (, a former U.S. national team rider and author of numerous books on bikes and bike maintenance including the pair of successful maintenance guides “Zinn and the Art of Mountain Bike Maintenance” – now available also on DVD, and “Zinn and the Art of Road Bike Maintenance,” as well as “Zinn and the Art of Triathlon Bikes” and “Zinn’s Cycling Primer: Maintenance Tips and Skill Building for Cyclists.”

Zinn’s regular column is devoted to addressing readers’ technical questions about bikes, their care and feeding and how we as riders can use them as comfortably and efficiently as possible. Readers can send brief technical questions directly to Zinn.

Follow Lennard on Twitter.