Deore XT is destined to live under the shadow of Shimano’s over-the-top XTR trust-fund baby. Don’t shed any tears, though, because XT may be the more stable and trustworthy member of the family. XTR’s creators occasionally overreach in their quest to out-perform their last opus. When they return to craft the next XT components, the engineers address those issues. As a result, XT can perform as well (sometimes better) as its haloed brother.
PB showed you Shimano’s 12-speed XT 8100 back in May, 2019
when it was first released. We were duly impressed with its performance and promised a long-term review to see if we could sus out any chinks in its armor. This is it.XT 8100 at a Glance
XT 8100 is as close to an all-new component ensemble as Shimano dares to release. Special ramps now ease the chain both down and up the 12-speed cassette. Assisted by a scientifically curated 12-speed chain, shifting speed is claimed to be over 30 percent faster.
The new Micro Spline freehub allows for a ten-tooth cog and the XT version provides a lightning fast (for Shimano) ten-degree engagement. Maximum gearing range from its 10 x 51-tooth spread is 510 percent and its shift levers can click off two gears in each direction with one push. In addition, the hollow aluminum cranks fit all popular widths and have direct-mount chainrings with steel teeth.
The brakes are new as well, copying XTR’s stiffer mid-clamp lever perches, while the brake rotors share XTR’s cool running stainless steel/aluminum sandwich technology and feather-light aluminum spiders. Two- and four-piston calipers are sold, and feature cooling fins on their newly-formulated brake pads. We reviewed
those earlier this year. The focus of this review is on the XT 12-speed drivetrain.
Hollowtech II Crankset
Shimano fans will recognize the Hollowtech II crankset. It’s basically the same hollow-forged aluminum design that the previous XTR ensemble used, upgraded with a direct-mount chainring. The non-drive-side still clamps to the splined axle, which has proven to be bomb-proof and simple over time.
Steel Chainring: The chainring teeth are tall and pointy, with profiles that stop short of the classic narrow-wide design, but still mirror the skip-tooth architecture. Shimano calls it “Dynamic Chain Engagement plus.” A lightweight aluminum spider is fixed to a plastic-encased steel sprocket with
• Hollow aluminum crankarms/direct-mount chainring
• 28, 30, 32, 34 & 36-tooth options
• Tubular steel axle
• Supports 142, 148, or 157mm axle spacing
• Q-factor: 178mm (narrow, 172mm option available)
• Weight: 616 to 660g (depending upon gearing)
• MSRP: $219.98 USD
tamper-proof screws. Reportedly, the small weight penalty of those steel teeth saves half the cost of an XTR chainring – and they last longer too.
Our Pivot Switchblade review bike had 175 millimeter crankarms, with a 30-tooth chainring and was configured for a 157-millimeter rear hub. The 178 millimeter Q-factor is the same as a standard 148-millimeter rear hub, so that was a non-issue.
First off, I expected to toss the chain at least once, but such was not the case. Shimano, it seems, has finally bridged the technology gap to SRAM’s narrow-wide tooth profile. The steel teeth run quietly too, and once the dust and grit polished off the sprocket’s black coating, there has been no further appreciable wear. Call me optimistic, but SRAM’s steel sprockets can go two seasons, so I expect XT to perform at least as well.
I am not sure why the plastic on the spider is necessary. My guess is that it’s a cosmetic treatment to hide the hardware at the four spider attachment points. Okay, but it looks a little cheap. Ending on a higher note, Shimano applies clear protective “helicopter tape” to the outer surfaces of the crankarms, which should keep your shoes from scuffing off the anodized coating. So far, they're looking fine.
Bottom line? One-by drivetrains have eliminated the need for bike makers to serialize chainrings and cranksets, so this is one of the first components they'll switch to save a few bucks. Shimano's Hollowtech II crankset design, however, has proven itself in all forms of competition. Add the more secure tooth profile and expected longevity of its hybrid steel chainring and it could prove to be a performance value in the long run.
More secure tooth profile +
Hard for me to get excited about the aesthetics.-
If you're a carbon fan - Shimano only makes aluminum cranks.
Heart and soul of XT is its 10 x 51-tooth, 12-speed cassette. Shimano's Achilles' heel in the one-by drivetrain battle was its Hyperglide freehub cassette, which limited its smallest cog to 11 teeth. The addition of the smaller Micro Spline freehub cassette enables a more competitive, ten-tooth cog and a proper 510-percent gearing spread. Hyperglide + shifting ramps now guide the chain up and down the cassette cogs, which might be its most important improvement.
XT lacks the titanium middle cogs that XTR touts.
• Requires Micro Spline driver
• 10 x 51 or 10 x 45 gearing options
• Maximum, 510% range
• two aluminum and ten steel cogs
• Ramps for both up- and down-shifts
• Lightweight aluminum 7-cog spider
• Weight: 461g ,10 -45t, 470g, 10-51t (reviewed)
• MSRP: $159.99 USD
The first two cogs are aluminum, riveted to a lightweight spider, along with five steel cogs. In Shimano tradition, the remaining steel cogs slide on individually. The XT vs XTR penalty is nearly 100 grams, with XT's 10x51 option weighing in at 470 vs 367 grams. Weigh the MSRPs, though, ($160 vs $380 USD) and that 100 grams should be no imposition.
The numbers game:
Compare Shimano XT's 10-12-14-16-18-21-24-28-33-39-45-51 ratios to SRAM Eagle' s 10 x 50-tooth (500% range), which is 10-12-14-16-18-21-24-28-32-36-42-50. The limitations of 1/2-inch pitch chain dictate the first eight steps be the same. The remaining four reveal different thought processes. As explained to me by a secret development rider, Shimano's 18-percent jump from the 33 to a 39 was chosen to keep the first nine steps as close as possible, while segregating the three largest cogs (clustered in even, six-tooth jumps), specifically as climbing gears. SRAM's gearing, on the other hand, was intended for riders who prefer a more sequential gearing progression across the cassette. True or not, Eagle and XT cassettes have distinctly different personalities on trail.
Even number jumps do not calculate to even steps. The six-tooth step between Shimano's 45 and 51 cogs is actually a smaller percentage
than the six-tooth step from the 33 to the 39 cog. Increasing the number of teeth between shifts to larger cogs helps to keep the delta between gears at the same percentage. Counterintuitive, perhaps, but that's why wide-range cassettes have parabolic curves.Ride Report
Shimano rises to the top on shifting performance. SRAM has also included ramps to ease the chain down to the smaller cogs, but XT is next level. Full power climbing shifts occasionally will emit a grunt from the cassette, but for the most part, the cassette runs quietly. Pop off a couple of up-shifts while powering over the top of a rolling climb and you'll feel nothing but a smooth transition to a faster gear. XTR introduced Hyperglide + shifting, but XT seems to run even more quietly, and that improved as the cogs wore in.
Did I notice the ten percent lower gear? Not really, but it was nice not to run out of shifts at high speed and still have a stump-puller climbing gear. Shimano's switch to a ten-tooth top gear has been long in coming. In his First Look, Mike Kazimer preferred Shimano's six-tooth gear spacing at the larger end of the cassette, because the 45 to the 51 felt like a smaller step than SRAM. I found more instances where I was clunking back and forth, spanning that mid-cassette jump than I did wishing my largest cogs were closer. Not huge, but worth noting.
Seven largest cogs are fixed to an aluminum spider.
Shimano does an incredible volume of real-world testing, so I assume there's a sizeable number of riders out there who will disagree with me. I would rather ride a cassette with more sequential steps. That said, I wasn't bothered enough to remove it for another option. Superlative shifting handily trumps a minor mid-cassette dead spot.
Best shifting cassette I've ridden+
470 grams is a little clunky at this level
Micro Spline Rear Hub
There's nothing massively special about Shimano's new XT hubs, besides being built well and the fact that they run glass smooth. The show is about the rear hub, where Micro Spline makes its debut on a more affordable platform. The main reason for Micro Spline was to adapt a smaller ten-tooth cog in order to bring Shimano up to speed in the one-by marketplace.
Micro Spline debuted with Shimano's not-quite-ready Scylence ratchet clutch. The noise-free system was pulled from the market, and may not return - which is a shame. Coasting without the buzz of ratchet pawls was a beautiful thing. XT, however, is nearly silent. It feels quick and positive, but Shimano worked some magic on the ten-degree engagement ratchet to reduce the pawls' contact pressure. Uncanny, but as speed picks up, the XT freehub ratchet sounds softer until it fades into the background noise. Exactly the opposite of other ratcheting hubs. I'm a fan.
• 36 points of engagement (10 degrees)
• 23 tooth Micro Spline freehub
• Shimano compatible only
• 142, 148 and 157mm (boost plus) widths supported
• 110 and 100mm, 15mm-axle front hubs
• Centerlock brake rotors only
• J-bend or straight-pull spoke flanges
• Weight: 147g (110mm F), 303g (148mm R), 310g (157mm R reviewed)
Micro Spline freehub has a 10-degree engagement.
Enough wheel makers have been granted use of Micro Spline to assuage customer fears of being trapped into purchasing Shimano hubs and wheels for life. The up side is that the new spline design will take massive amounts of torque when constructed from aluminum - so, lighter and stronger, and no more galled freehub splines.
Smooth rolling and user rebuildable+
Very quiet freehub ratchet.
No XT six-bolt brake rotor option
Rapidfire Plus Shift Lever
After many experiments with indexing and ergonomics, and some dark periods of indiscernible feedback, Shimano gets it spot on with XT 8100's shift levers. Shifts are crisp and each gear change is telegraphed to the rider with a distinct feel and an audible click. Both the thumb take-up and finger release operate with similar pressure and throw distance, which makes shifting intuitive and precise.
"Instant Release" triggers shifts to smaller cogs with the first movement of the release lever, which is claimed to improve up-shifting by 20 percent. Two shifts can be executed with one movement by either lever, and firm index points eliminate any guessing.
• I-Spec direct-mount or discrete clamp options
• Shifts two gears with one push in either direction
• Contoured plastic touch points with rubber coated thumb paddle
• Trigger or push action release lever
• Positive feeling action with more defined index points
• Weight: 120g average
• MSRP: $60.99 USD
Shifting firmness feels similar to SRAM's Eagle XX1 or X01 triggers, but with better ergonomics at the touch points. Shimano fans will be happy to know that the release lever can still be operated by thumb or forefinger action.
These are the best feeling shifters I've seen from Shimano. I like the firm feedback the index action translates with each gear change. I wear gloves, but the ergonomics play just as well with bare hands. In combination with Shimano's double action Hyperglide + cassette ramps, the new XT 12-speed lever's feel and performance are top notch.
Best feeling analog shifter Shimano has produced+
Consistent throw and intuitive feedback.
Why did we have to wait so long?
Shadow Plus SGS Derailleur
Shimano's most recent improvement has been to tuck as many of the rear changer's vital parts out of harm's way as possible. What does protrude beyond the XT 12-speed derailleur's pivot knuckle is angled to ensure a glancing blow. Larger diameter 13-tooth jockey pulleys ride on sealed ball bearings inside a sturdy cage that is also designed to withstand a beating.
• Long or mid-cage options
• Larger, 13-tooth ball bearing pulleys
• Adjustable band clutch
• Reduced cage tension in low gears
• Recessed architecture
• Sturdy steel and aluminum cage plates
• Weight: 284g
• MSRP: $114.99 USD
This changer shares XTR's adjustable band type clutch and reduced cage tension in lower gears. The SGS model reviewed here handles the wide-range 10 x 51 cassette. A mid-cage option is available for customers who choose the close-ratio 10 x 45-tooth cassette.Ride Report
One indicator of a stable rear derailleur is how well it can handle adversity, like brush winding into the pulleys, or leaf litter clogging the cassette. Few disturbances can ruin a mountain biker's flow faster than a chain randomly skipping over a tiny stick lodged in between cassette cogs or a jockey pulley. Autumn in Southern California guarantees those moments, so it came as a pleasant surprise that the XT cassette and derailleur shrugged off the barrage of dry brush and prairie grass leaning into the singletracks. A couple of chain skips, then silence, and my precious flow would resume. I could count on it. That's not how it normally goes.
Typically, you can set and forget a Shimano derailleur. Maybe you'll need to turn an adjustment barrel once to compensate for compressed housing, but that's it. So it was with my XT review. I needed one-half turn of the adjustment barrel three rides in and shifting has remained stable to date. My SRAM X01 Eagle bike is about the same age as the XT bike and it's already developed the usual free play at the upper pivot where the derailleur mounts to the hanger. I've been riding the heck out of both bikes this season and XT's pivot bushing is still like new.
Body designed to deflect impacts.
Sturdy and stable+
Tucked in design incurred minimal trauma
Matte black finish top to bottom always looks dirty
Shimano XT vs. SRAM X01
SRAM's and Shimano's halo analog groups are Eagle XX1 and XTR. Their second-tier groups are Eagle X01 and XT 8100, so I'll throw them into the ring together. XT may be closer in price and weight to SRAM's GX group, but this fight is about how XT stacks up against X01.
Shifting performance of the two contenders is close, but Shimano has slightly better shift ergonomics. While both cassettes use ramps to guide the chain in each direction, Shimano's is the smoother and faster shifting of the pair.
Starting with the basic drivetrain (crankset, 32-tooth chainring, chain, rear-derailleur, and cassette), X01 comes out swinging, with an average weight that is
almost 250 grams lighter. Shimano takes the first hit in the crankset (620g vs 483g) boom, and then another punch in the 12-speed cassette (470g vs 357g). Ouch! But, the weight advantage of SRAM's carbon cranks and one-piece CNC-machined Powerdome cassette can't hold up to Shimano's MSRP - a $650 USD blow to the head from XT. Ba-boom! X01 wobbles back towards XT, swinging wildly for 650 bucks worth of tangible performance, but can't quite connect. The decision goes to XT.Pinkbike's Take: