Back in May Shimano dropped the new 12-speed Deore M6100 drivetrain, offering riders a dozen speeds for fewer coins. I’ve mounted the complete drivetrain on two different bikes and to in a couple hundred miles over the last few months, and here’s what I’ve learned.
Installation
Regular readers may recall seeing the new Deore drivetrain mounted to the teeny, tiny 29ie build I put together back in October. I assembled that new bike from scratch with Deore parts, and after my daughter took the bike out on a few rides, I swapped the entire drivetrain over to my own hardtail 29er. For those keeping track, that’s two full installs, and one un-install.
I used the XT-level MT800 for this drivetrain, instead of the Deore-level MT52. I needed an adapter for my older Shimano-compatible bottom bracket tool to fit the splines, but once that was sorted, the two halves went on without a hitch.
Next, I installed the crank set. Out of the box mine weighed 794g which isn’t lightweight by any means but at the same time, it doesn’t feel overbuilt. Upon inspection, the quality of the machining and the graphics are both impressive for such a budget-friendly component. A nut on the non-drive side draws the two arms together while opposing hex bolts cinch the non-drive side arm to the shaft. I tested the crank with a 32T chain ring, though the set is also available with a 30T ring. The crank set with chain ring is priced at about $95 (available at Backcountry). Somehow the SLX crank set is priced at just $10 more and drops 100g off the weight of the Deore version so that might be worth looking info if you’re putting together your own drivetrain.
The Deore 12-speed cassette (available at Backcountry) is only compatible with the newish Shimano Micospline freehub, so older wheels will need a new hub or freehub body. I’ve been testing the drivetrain with a set of XT wheels, and the whole system goes together well. The $92 cassette blossoms from a 10-tooth small cog on the outside to a massive 51-tooth cog on the inside. The actual weight of my cassette is 593g, made heavier and more durable than SLX and other models by its 12 steel cogs.
I found the $32 I-Spec shifter (available at JensonUSA) installation to be the trickiest part of both installs, though to be fair it wasn’t that bad. Orienting and threading the nut takes patience along with a little trial and error; I ended up stripping one of the nuts the first time and had to order a $12 replacement. Lesson learned.
The Deore derailleur that retails for $55 MSRP (at JensonUSA) goes on just like any other and tuning it using the usual high, low, and B screws is straightforward. Like most bike parts, the printed, paper user manual included in the box is worthless. Honestly, I wish they would just skip the printout entirely and call it green. Fortunately, Shimano provides PDF versions of the unhelpful user manual and the dealer manual, which is what home mechanics actually need. The manual does a great job explaining how to install everything with clear illustrations and I was able to follow along to get everything dialed with no issues.
For my first installation, I used a Deore M6100 chain. When it came time to move everything to my larger bike, the chain was too short so I used an XT chain I happened to have. While the XT chain is heavier by about 20g, it’s supposed to be much more durable and longer-lasting than the Deore chain. Additionally, the XT chain features Hyperglide+ for improved shifting performance. While the XT chain costs about $20 more, it’s a valuable upgrade.
All of Shimano’s 12-speed chains include a set of quick links for joining the two ends. The company says the links are not re-useable, though I was able to re-use the same set of links from one install to the next. I also took a chance on a bag of six pairs of 12-speed links on Amazon selling for about the same price as a single Shimano-branded pair. So far so good: the off-brand links work just as well as the originals.
On the trail
I’ll cut right to the chase and say I’ve been thoroughly impressed with the performance of the Shimano Deore 12-speed drivetrain. I have pedaled in all conditions from dusty and dry, to wet and sticky. I’ve left the trail and bushwacked my way across forest floors deep with dry leaves and sticks, and I’ve spun the pedals head down for miles at a time, laying down more than enough watts to power a commercial pizza oven.
Shifting performance is noticeably smooth, fast, and accurate. Upshifting three, four, or even five gears at a time with a single push of the lever works flawlessly, and I haven’t experienced any kinks or a need to back off a shift to sort things out. Note that the 12-speed Deore shifter and derailleur can only downshift one gear at a time.
The shift paddles feature a grooved texture for a nice glove feel and reduced finger slip. The back side of the downshift paddle extends out to make it easy to reach with an index finger depending on preference and hand position. I noticed the paddles aren’t quite as large as those on SRAM and Box drivetrains, which has become even more evident when wearing thicker gloves on cool rides this fall. For those who are used to Shimano shifter paddles, this won’t be much of an issue, but for others, it may take a short adjustment period.
Back in 2019 I tested the 12-speed XT drivetrain and I have to say, the shifting performance with the Deore drivetrain feels awfully similar. Honestly beyond weight and possibly durability considerations, I have to say there is very little performance difference between the two. Shimano did such I good job with Deore that I suspect it may undercut sales of their higher end, more expensive groups.
Chain retention has been excellent. I haven’t dropped the chain once in all of my testing, which is saying a lot considering my test bike is a hardtail and with my riding style, other drivetrains haven’t fared as well. The Deore 12-speed derailleur features a clutch mechanism to reduce chain movement, and naturally the chain and chainring are narrow-wide to help with retention. Over rough, jangly descents the whole system is fairly quiet and worry-free.
I’ve found the gear range to be more than adequate when paired with the 32T chain ring. It’s nice to have a small, 10T cog to really go fast on the flats and descents. The gear range is progressive so in the early and mid-gears it feels like there can’t possibly be much left of the cassette when the trail turns steep. However, once you hit that 28T cog, the tooth counts jump by five, then six all the way up to 51T. A few times I worried I wouldn’t make it to the top of a steep section because I only had two or three clicks left, before realizing those final clicks make a big difference. My tire grip generally ran out before the gears did on the steepest sections.
After riding through a brief sandy wash in the trail I started hearing some clicking at the cassette and wondered if the derailleur needed to be adjusted. It turned out to be a bit of fine sand that had attached itself to my chain, and the noise laid bare just how tight the tolerances are. Cleaning and re-lubing the chain eliminated the noise and I haven’t had to adjust the derailleur at all.
Perhaps due to abrasion from the sand, I have noticed some rust forming on the edges of a few cassette teeth. The otherwise shiny plating on the all-steel cassette seems to have worn off in a few spots so clearly it’s important to keep a clean, well-lubed chain and a dry drivetrain.
I tend to be tough on bottom brackets and often ride in some pretty wet and muddy conditions, where creaky bottom brackets come with the territory. So far, after riding with the XT bottom bracket this fall I haven’t noticed any creaking, wobbling, or added pedaling resistance.
The derailleur has proven to be surprisingly robust despite venturing off trail and grinding through sticks and vines. I lost track of the number of times I pulled leaves, stalks, sticks, and stems out of the jockey wheels, and yet, the derailleur continues to work flawlessly.
Conclusion
Based on performance and durability I can confidently recommend the new Shimano Deore 12-speed drivetrain without reservation. Perhaps the only thing buyers will be missing over more expensive drivetrains is weight savings, but overall riders will be hard pressed to find a better value in mountain biking today.
A complete drivetrain, minus the bottom bracket, retails for $298USD.
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Dec 26, 2020
Dec 27, 2020