What it is: Shimano's mid-level 12 speed mountain bike drivetrain offering
Intro:
I've been running the 'new' XT for about a year now. As usual, the reviews from other publications cover things like weight, features, and details really well, so I'll focus on the things that I found interesting or problematic in the last year or where my experiences differ from other articles.
I went with XT for the shifty parts, cranks, and cassette. I did not try the XT hubs, as their engagement is just too low for what I prefer, or their brakes, as I've not had great luck with their brakes in the past. As you may have seen in prior reviews, I've been on SRAM drivetrains for the last few years and my experiences with the M8000 were very mixed.
Thoughts:
I generally don't focus much on drivetrains: they are either heavy or light, shift smooth or poor, expensive or cheap. It seems difficult to me to really differentiate yourself with the same technology outside of price, weight, and reliability.
For starters, as you likely know, the cassette requires a different freehub body: MicroSpline. I was not a huge fan of the HG freehub bodies, as the teeth from the cassette would dig into the freehub and make notches. The XD design always seemed more refined and sensible to me, until I had a XD cassette seize onto a freehub, resulting in the loss of a very expensive XX1 cassette. In retrospect, both designs have their ups and downs: HG is less error prone, but more likely to take freehub damage; XD is more refined, but you have to be real cautious about seizing and cross threading. Ultimately, I think MicroSpline falls into the same category, it isn't a huge improvement over HG in any way that I could really find, but it is required for the new Shimano offerings, so I felt it was worth mentioning.
After putting time on this drivetrain over the last year, the most obvious performance difference to me was the shifting under load or power. The XT drivetrain allows you to shift fairly indiscriminately of what you are doing and barely complains at all about improperly timed shifts that you perform under power. If you made the same shifts on a SRAM drivetrain, it would feel like the chain was going to explode.
I actually had this very experience riding a friend's bike with a GX drivetrain. I hopped on it and started pedaling a bit, then shifted the same way I was used to with the new XT, and the result was a terrible noise and feeling like the bike was going to shatter. Thankfully, nothing broke, but it highlighted the main difference to me with this drivetrain compared to the other main offering on the marketplace.
All that said, I do have some complaints and issues.
Reliability
My previous experiences with Shimano's 11 speed offering were not that great. I found the drivetrain required constant adjustment with the adjuster and the rear mech had all sorts of clutch issues. I ran several of them on various bikes and just never got along with it. Thankfully, none of this was an issue here.
I've barely touched the tension adjuster and the rear mech has required almost 0 adjustment the entire time I had it. That was a welcome change, until about 3 months in...
The clutch on the Shimano rear mechs seems to be a tripping point for them. The last iteration of their XT drivetrain had issues and this one certainly does. I know at least 3 people that had to warranty theirs, out of the four I know running this drivetrain, and I started having issues until I split the rear mech open on a rock (my fault, not the mech).
The issue initially shows itself as a shifting problem, where you'll try to upshift and it just won't do anything. I realized the clutch was the culprit when I turned it off and it shifted where I wanted it, but then broke when I switched it back on. I did adjust the clutch and reduce tension, which helped, but that started creating issues with the chain dropping and eventually the clutch wasn't working very well. I was close to trying to warranty it, then I smashed it on a rock and split it open, which required I get a new mech.
The others I know with the same issue had similar symptoms. My latest mech has been fine, but thanks to the pandemic, most of my riding has been limited this year, so maybe it'll crop up more down the line. I have heard they addressed these issues, but that's yet to be seen for me. I wouldn't let this deter me from buying, but it's something to note.
Minor complaints
The issue above is the most concerning problem I've had or heard of with this drivetrain, but I do have some minor gripes.
First, after less than a few hundred miles, the cranks start to look really...cheap:
I'm used to seeing wear here, but after 2 1/2 years on the same SRAM cranks, they didn't look nearly as worn or poor as these do after a few hundred miles. I'll accept my share of the blame in pedaling technique, but the peeling plastic, worn out logo, and finish wear just seems poor to me given how new these are and other cranks look more aesthetically pleasing even after a longer period of time.
Also, touching on the rear mech a bit, I really miss the button that SRAM drivetrains have to lock the rear mech down. I know, it's a minor thing, but when I work on the bike or remove the rear wheel, I constantly miss the ability to do so easier and cleaner than I can with the Shimano products.
Finally, the lever feel is a bit different. The SRAM levers feel very engaging and tight, whereas the SRAM shifters feel a bit sloppier and looser. Rather than get that instant engagement of the lever like you do with SRAM, there is a small amount of play before it engages. It's not a huge deal and you get over it eventually, but it's there and I'm not the biggest fan. So who would I recommend this to?
Anyone that needs a drivetrain that has the correct freehub and isn't gram counting.
Unlike my other reviews, there isn't really a lot to say here. The drivetrain pedals, wears well, and is reliable, clutch issues aside.
I recently gave up on SRAM after they failed to warranty a 1 month old pair of cranks that broke and I can't say I'm disappointed with the change, but it's not a massive improvement either. It does what you want it to without a lot of fuss, but it isn't going to magically change your ride like good brakes or suspension will.
Comparisons:
vs SRAM X01 : I ran X01 for years, so this is the easiest comparison to make. The X01 drivetrain is easier to work on thanks to the rear mech lock button, the shifter is more engaging, and they don't seem to have the same clutch issues I encountered. SRAM is also better about selling small parts, whereas Shimano tends to focus more on entire replacement. The customer service from both companies is mediocre, at best, so you don't get a clear win one way or another. Personally, I'll continue to use XT since my bike is set up for it, but I think it comes down to minor gripes. Ultimately the X01 is better engineered, but I wouldn't rip off a XT drivetrain to replace it, the differences just aren't that significant.
Pros:
Shifting performance is incredible
Readily available and reasonably inexpensive
Reliable especially compared to previous iterations (clutch issues aside)
Chain and cassette wear appears to be slower than SRAM counterparts
Weight isn't mind blowing, but isn't unreasonable either
Cons:
Clutch reliability issues seem somewhat common
Slightly sloppy lever feel
Requires yet another freehub standard*
Cranks are aesthetically poor after a few months of riding
* The freehub issues raise an interesting point that isn't a factor at the time of writing, but was at release. For some bizarre reason, Shimano decided to only license the MicroSpline freehub to a few companies at launch, which meant you were very limited in drivetrain choice. I believe this is still the case to some degree, however most manufacturers are offering it now. I don't have a full grasp on the landscape, but it'd be worth checking with your hub manufacturer to see if they offer MicroSpline, because some still may not.