2011 Shimano XTR Trail Drivetrain
The 2011 XTR Trail crankset uses what Shimano calls CloseStep gearing - 42, 32, and a 24 tooth small ring. When teamed up with the new 11-36 XTR cassette it provides an easier low range (56.6" vs. 58.3" of rollout for a standard setup) and is claimed to result in both less shifting and less chain tension that causes friction. But the question is, is it noticeable in real world conditions and does it benefit the user?
Shimano's 2011 XTR crankset is part of their Dyna-Sys drivetrain system that also includes a 10 speed 11-36 cassette. The new cranks use what Shimano calls CloseStep gearing that consists of a 42, 32 and slightly larger than average 24 tooth chainrings. Don't panic if you live in the midst of steep terrain or are a larger rider, the 24 tooth ring combined with a 36 tooth cog actually produces an easier gear than the current 22 x 32 combo (56.6" vs. 58.3" of rollout for a stanadard setup
). The larger granny ring should also work better with a lot of suspension designs as it is closer in size the the middle ring that most bikes are designed around. In usual Shimano style, front shifting has been massaged to exceed expectations via many shift assists on the rings themselves. The Trail crank shown above comes in triple configuration, but a double version will also be available in 40/28 and a racer and hammer head friendly 42/30.
2011 XTR Trail triple crankset details
- Entirely new crank for 2011
- CloseStep trail-tuned gearing: 42-32-24T
- Dual Spike chainring technology
- 10-speed specific
- Standard 104/64 bolt pattern
- Durable Ti/Carbon composite 32-tooth Primary Driving Gear
- Double ring versions also available
- Bottom bracket forgoes bearing tension adjuster
I fondly remember my early days of mountain biking and of all the cool parts that got my teenage heart pumping, Shimano's XTR cassette was the one bit that nearly put me into fibrillation. It still has the same effect today! The three piece aluminum spidered block uses titanium for the five largest cogs. It is available in both 11-36 and 11-34 spreads.
The key to the Dyna-Sys setup is Shimano's new 11-36 spread cassette that offers a wide gear range for the average trail rider, but also operates with the composite 32 tooth ring so the rider has to shift less than before. Shimano says that if you use or have used a triple ring crankset you'll be familiar with having to make multiple shifts in the rear every time you drop down to the smallest chainring, otherwise you quickly loose all momentum on the trail. Having been doing my fair share of climbing lately, I'd have to say that when I've dropped down to the granny ring I have been forced to drop multiple gears on the cassette as to not quickly come to a standstill - one just doesn't think about it when riding. By using a 24 tooth small ring and revised cassette gearing Shimano claims that a rider will now have to perform only a single recovery shift as opposed to having to do two or three on another system. The 36 tooth large cog, the five largest are titanium by the way, means that riders can stay in the middle ring much longer and shift the front derailleur even less.
Shimano also says that the Dyna-Sys design reduces chain tension as well, which greatly reduces drivetrain frictions. I was told there is 30% less drivetrain tension when using Shimano's 32 tooth ring and 36 tooth combo when compared to a standard drivetrain and in the 22 tooth ring and 26 tooth cog. 30% certainly sounds like a lot and I'm interested to discover if there really is a noticeable difference under load during the longterm test that you can read about down the road.
2011 XTR Trail cassette details
- Entirely new cassette for 2011
- Wide range 11-36 tooth spread
- Five largest cogs are titanium
- Three piece aluminum spider design
- Standard 11-34 is also available
Geek out alert! These two pieces of gigantic mock chain clearly show the differences between the high end road and mountain chains. The HG-X 10 speed mountain bike chain is designed to work only with mountain bike chainrings and cogs, don't try and put it on your road bike, and vice versa. The directional chain uses different inner and out links, each side designed to interact with either the rings or cogs.
While the new crankset and cassette are no doubt going to get all the attention, the key to Shimano's drivetrain may well be it's new HG-X super narrow chain. The mountain bike specific chain uses differently shaped plates than its tarmac brother that interact much better with Shimano's mountain bike rings. Unlike many other chains, the HG-X doesn't feature any plate cutouts that would shave a few grams because Shimano feels that it increases the chance of twisted plates. An important feature of the chain, and one that many mechanics may not realize, is that the HG-X is actually directional - there is an inside and an outside to it! Each of the four plates in a single link of chain (left and right, inner and outer
) have different chamfers to their edges that are designed to mate perfectly with the shift points found on the chainrings and cassette. The right side/outer plates are shaped to work best when sifting over the chainrings, while the left side/inner plates mate better with the cassette's tooth profile. There are some very smart people at Shimano that look at the smallest details! For those wondering which side faces out and which side faces in, the logo, whether it is XTR or Dura Ace, faces out.
The new 10 speed XTR derailleur uses revised A-arm geometry that results in less cable tension being required for a lighter feel and less sensitivity, as well as reducing the chance of skipping as you pedal over rough terrain. The outer cage is carbon, the inner is aluminum
The 2011 XTR rear derailleur still uses Shimano's low profile Shadow design, but receives refinements that alter both shift effort and reliability, as well as addressing the issue of skipping while under load when pedalling over rough terrain. Previous models had a very obviously different level of effort needed at the shift lever depending on which cog you were shifting to, but Shimano has changed the geometry of the A-arm (the piece that holds the housing stop
) to lower the cable tension, and in turn make for a more reliable system that requires nearly the same shift effort no matter what cog you are shifting to. The cage consists of a carbon outer plate that saves a few grams, and an aluminum inner plate to keep everything stiff and reliable.
A functioning XTR derailleur prototype that was used to test A-arm geometry. This was one well used unit.
2011 XTR Trail derailleur details
- Entirely new derailleur for 2011
- Revised A-arm geometry for lighter and more linear action
- A-arm geo also greatly reduces skipping when pedalling hard over rough terrain
- Carbon outer plate, alloy inner plate
- Shimano Shadow design
The XTR shifters allow you to adjust the pod laterally for better ergonomics and you can also use Shimano's i-spec bracket to mount it the same perch as the lever. A mode converter allows both 2 and 3 ring use without have to set up your limit screws as a hard stop.
2011 XTR Trail derailleur details
- Can mount directly to brake lever via Shimano's i-spec bracket
- Adjustable mount lets you slide the shifter to different bar positions
- 2x / 3x mode converter adapts to double and triple cranksets
The guts. Smart people build these things! This display shifter shows just how each small piece interacts with its neighbor to pull and release just the right amount of cable.
While Shimano's XTR family was at one point the only game in town when it came to a complete top tier group, this has changed over the years as the competitors have made inroads when in comes to no compromise performance. This must have given Shimano fuel for the fire as for 2011 they have released two different XTR groups, one geared for the racer and the other for the trail rider who wants the same level of performance, but in a more user friendly package. I was able to put in some time on this new XTR Trail group while riding some Downieville's fast and demanding trails and came away impressed with what Shimano has been able to do.
My Trek Remedy equipped with Shimano's new 10 speed XTR Trail group
The shifters have a slightly different feel to them for 2011, with a lighter touch and stronger detents that results in a more tactile sensation while out on the trail. There is no doubt that there is action happening below each and every time that you grab a gear in either direction. Shimano's Multi and Instant release features, along with 2-Way Release, are still present on the shifters, and I am especially fond of being able to drop or pick up gears from more than one finger position. Although it may not sound useful, it made itself very handy out on the trail and in real world conditions. My Remedy was equipped with Shimano's triple ring XTR crankset that uses their CloseStep gearing. Shimano says that the CloseStep 42,32, and slightly larger 24 tooth small ring work with their 10 speed cassette (available in both 11-36 and 11-32
) to provide a system that requires less shifting, especially recovery shifts, than a standard three ring and common 9 speed cassette. While I'll need to put more time in on the groupset on more familiar terrain to verify that claim, what was quickly apparent was Shimano's near instantaneous front shifting. Shifting up to a larger ring seemed to happen as quickly as I could work my fingers over the left shifter paddle, it was even an improvement on Shimano's already well known impressive front shifting. Rear shifting was also superb throughout the ride, with the chain moving over the cassette with no issues and feeling remarkably quick. No tension adjustment was needed at any point during the ride despite the addition of an extra cog and the resulting tighter spacing. Holding the new drivetrain parts in your hand for a closer inspection reveals an incredible amount of engineering work to each and every piece, but the new directional chain really takes the cake when talking about minuscule details. The new XTR drivetrain's performance is due to the sum of its parts, but I'd love to discover just how much the chain, with its four uniquely shaped plates per link, add to the overall shift quality of the group.
The last few years have seen immense improvements made to mountain bike drivetrains. Not only can riders expect more gears out back, wider ranges, and more chainring combination options, but also much more reliable shifting compared to what was offered only a few short years ago. Despite the common cry that a 10 speed system on a mountain bike is surely asking for trouble, this has yet to be the case in my experience, although the new XTR group hasn't been put through a proper British Columbia rainy season beatdown under me. I'll be putting more time on the new XTR Trail group throughout the remaining summer months and into the rainy fall season - stay tuned for a complete long term review down the road.
You can also read my early impressions of the completely new XTR Trail brake as well
Visit Shimano's website
to see their entire lineup of components.Are you excited about what Shimano has coming down the line? Looking forward to having a go on the XTR drivetrain? Tell us below?