I have been weighing parts, installing parts, and asking Shimano folks questions about the new drive train and brake parts that make up the Dyna Sys 10 speed group. Here is an update on where I am at with the group so far…………

Note: Click on any photo to enlarge it.

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Our test mule for the XT Dyna Sys 10 speed group: The Stumpjumper Expert Carbon 29″er.

I have most of the group mounted to our test bike. The one snafu I ran into was mis-spec’ing the front derailluer. I asked for a low mount top pull derailluer, when it needed to be a high mount. Arrgh! I will hopefully be able to rectify this situation soon. However; this brings up an interesting point. Shimano folks told us at the presentation I attended that the 10 speed groups:XTR, XT, and SLX, were a “paradigm shift” in componentry. In other words, you are not going to be able to use 9 speed components with 10 speed systems or 10 speed components with 9 speed systems. The geometry of the derailleurs is different along with the amount of cable that the shifters pull. The chain is also said to be incompatible with 9 speed systems. Here’s what I experienced trying to use the SLX 9 speed front derailluer that I needed to use to make this bike rideable for now:

The shifter, as I mentioned, pulls more cable than the 9 speed models do. So, I had to compensate by having a ridiculously slack cable while in the granny position for now. I also had to limit the outer travel of the derailluer so as to not have the chain shift off the big ring, and more importantly, not have the inner cage of the 9 speed SLX hit the middle ring. This is exacerbated by the smaller big ring size that Dyna Sys employs, (42T vs 44T), which I allowed for by slightly cheating on the height of the derailleur set up. In the end, I had a marginally good set up that rubs in certain combinations, but……..oh well! I guess they were right all along about the parts not working across generations. This will obviously all go away once the correct front derailluer comes in.

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Okay, enough of that! Let’s get on with some impressions I have of the group so far. Starting with the brakes, I noted that the perches and for that matter, the shifter clamps, were pretty burly. Shimano Skunk Works rider Paul Thomasberg told me at the presentation that Shimano tends to overbuild things. These clamps and brake perches are evidence of the mindset Shimano has to have reliable, durable parts. This comes with a sacrifice to weight, and in the case of the brake levers, no split perch. Bummer! However; the clamps opened quite wide when I unscrewed the fastener so I did not have to worry about scarring the Ritchey carbon handle bar on this bike at all.

xtdynasys2010-1 004The brake levers/master cylinders look like something from the movie “Transformers“, and they are definitely bigger in size than some levers out there. The levers are a nice shape- not too wide, not too narrow- and have a wide pivot which gives them a solid feel. I would call them two finger levers, as far as length goes. I’ll delve more into features later, but take note of the “Free Stroke” adjuster here, which is supposed to help you dial in a solid lever feel, or a very soft lever feel, or something in between. Of course, Shimano has always used a mineral oil for brake fluid and continues to do so with the new brakes.

xtdynasys2010-1 011The XT calipers look pretty familiar. Open on top for better cooling, and dual pistons with a one piece forging. The rotors we are using here are the six bolt variety with a two piece architecture. An aluminum “spider” supports a stainless steel rotor. Pretty much the same stuff we have seen before here. Shimano didn’t do anything new with brakes until you get to the XTR level.

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The XT Dyna Sys rear derailluer is new; however, and as I stated before, it has a different geometry to better follow a 10 speed cassette and is optimized to work with the 10 speed shifter. Called “Long Arm” technology, the system is said to require less cable tension and add leverage to the system. What isn’t new is how the Shadow architecture snugs up into the cassette better and gets rid of the old loop of cable rear derailleurs used to have. This is nice for those who have chunky, tight trails to maneuver through. There is definitely less of a chance of biffing your derailluer with this set up. That 10 speed cassette has two aluminum carriers, each holding three cogs apiece. Then you have a single cog and a loose spacer. The next two smaller cogs have wider bases to space them properly, and the smallest is the cog next to the lock ring and has a wider base as well.

xtdynasys2010-1 008The smallest cog is an eleven tooth. The cogs run like this, from smallest to largest; 11, 13, 15, 17, 19, 21, 24, 28, 32, and the 36 tooth cog rounds out the selection. The typical ramps and profiled teeth you’d expect are here as well. Note that Shimano claims they “tightened up” the middle of the cassettes gearing ratios to better reflect the gears most riders seem to be using.

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Here’s the special 10 speed mountain bike specific chain Shimano came up with to make this work seamlessly and flawlessly. (That’s what they told us anyway!) This is a ground up new design and not a re-hash of a 10 speed road chain. In fact, Shimano claims it is the “first ever mountain bike specific 10 speed chain”. It is directional, (meaning you shouldn’t run the chain with the logos facing inwards), as the inner plates are designed to pick up to the next largest cog on an HG 10 speed cassette, and the outer plates are designed to pick up the pins and ramps on the front chain wheels more efficiently. In fact, Paul Thomasberg told me that the new chain will cause Shimano to adapt many of the new features found in the mountain 10 speed chain into whatever new road 10 speed chain they design next. Interestingly, Paul also related to me that prototype chains were all hand made, by one man, link by link, in Japan, at an astounding cost of approximately $40,000 a piece! He also said he tested several prototype chains before a final design was settled on. This is said to have resulted in the smoothest shifting mountain bike system yet. We’ll certainly put that claim to the test!

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Here’s a look at the “underbelly” of the crank set. XT Dyna Sys will now have the carbon composite chain wheel in the middle, which you can see here. It has the ramps, profiles and pick ups to help the HG-X chain move up from the granny gear to the middle ring. The outside ring is a highly machined, thick aluminum affair with riveted in pick up pins and machined in profiles to aid in shifting. Interestingly, the granny ring even has profiled teeth. The BCD of the chain rings remains the same as before on the Dyna Sys XT. Note that the asymmetrical chain has no markings on the inner plates.

xtdynasys2010-1 003The shifting is done by what is now a familiar Shimano Dual release trigger system. There is an optical display window which is removable, (I removed the ones on the shifters here before mounting the shifters), and has a round, badged cover that you can use in its stead, just like 9 speed XT. The shifter paddles are longer and thinner than SRAM triggers, and we’ll see how I get on with them after dialing in the system.

Weights: Here are the weights for the components I was sent as weighed by myself on a digital scale. (Your mileage may vary)
Rotors: 160mm 6 bolt type: 160gm
Calipers w/hoses and levers, system pre-bled w/mineral oil: F- 290gm R- 300gm (Hoses will be shortened eventually making these weights slightly heavy)
Crankset: (Including standard Shimano BB bearings and sleeve)- 850 gms (Note: The Specialized test mule has press fit Shimano bearings and we did not use the supplied BB)
Shifters: (Each w/shifter cable installed) 140gms
Cassette: 11-36T- 340gms
Chain: 280 gms
Rear Derailleur: 230 gms
Front Derailleur: 140 gms (Note: We have the wrong derailluer and will give the weight of the high mount, top pull derailleur when it arrives)

I will be in contact with a Shimano marketing/tech person who is going to answer some of your questions. If you have anything you want me to forward, (within reason), put your question in the comments and I’ll see what I can do. I can tell you now that an XT level 2X10 system will “eventually come out”. I didn’t get a time line on when that might be though. MSRP’s will be coming along in a later post as well. Until then, I will be riding what I have here, shortening brake hoses, adjusting things if necessary, and I will report back with an update in a couple of weeks, hopefully.

Note: This component group was provided by Shimano for evaluation free of charge. I am not being bribed or paid for this review. I will strive to give my honest opinions throughout.