I will tell you how the new XTR stuff doesn’t suck at a later date, but first let’s get our minds around this Dyna-Sys program. As a guy who thought 8 speeds was one gear too many, let me tell you that a ten-speed drivetrain really does have some advantages, especially in Shimano’s Dyna-sys 3×10 layout.
Ten-speed drivetrains may be new to MTB, but they developed out of the needs of road racers; guys who need closely-spaced gearing to keep that one mad cadence going the entire race. And anyone who has done any touring has probably wished for another gear in between that one that’s too hard and the one that’s too easy.
A narrower chain makes it possible to put ten freewheel cogs (11-36) in the same space as nine. It’s a directional chain with four different plate profiles; the outside links are optimized for front shifting while the inside links are designed moving smoothly across the rear. Shimano claims this narrower chain is just as strong as a 9 speed chain, and better at mud shedding. Time will tell on that promise. A long-term review is certainly in order.
The 24-32-42 range in front combined with the bigger stack in back has several advantages, which were discovered during a highly technical ride through the Lakes Basin area of Plumas National Forest. 24-32-42. Closely spaced for quicker shifts. The bigger chainrings in front combined with bigger gears in back keep me in the big or middle ring longer. This just feels right, and keeps the momentum up to par with the gnarly course. At Lakes Basin, sudden changes in terrain steepness are handled without the drama of bailing to granny gear, so efficiency, momentum and speed are smoothly maintained. And when you do bail to granny, the 24 teeth provide a bigger, more efficient gear that doesn’t torque the drivetrain all to heck like a smaller ring can do.
Another advantage of the closely-spaced front chainrings is that they work with the various popular suspension designs better. Many suspension designs are optimized for middle-ring performance, with compromises made for the small and large rings. With less difference between the cog sizes, there’s less change in the direction of chain pull in relation to the pivots, so there is less change in the suspension action in different chainrings. Installed on my Santa Cruz Blur LT, I found the suspension action more consistent in all three chainrings. This did pan out on the trail.
The above verbiage falls under what Shimano calls “Dynamic Power Transfer” Catchy, huh? The other side of the corporate mumbo-jumbo is “System Optimized Stability” My interpretation is that Shimano has been working on advancing their concept of “Light Action” shifting. They did this by changing the geometry of the Shadow rear derailleur to arrive at a more linear shift force requirement through the gears. So that last push into the larger chainrings requires about the same force as the shifts on the smaller cogs.
All of this work is quantifiable on the trail. XTR is good stuff, as anyone who can afford it will tell you. Fortunately, the availability of the new technology spans a wide section of the Shimano line, namely the XT and SLX groups. But in some sections, it’s still about the rider, as Matt from Shimano proves…