Shimano 12-Speed Mountain Bike Drivetrains Compared

In the world of mountain biking, the advancements in drivetrain technology have never been more impressive. Even budget-friendly entry-level mountain bikes now come equipped with single chainring wide-range groupsets, revolutionizing the riding experience. After logging countless miles on a Polygon Siskiu T7, featuring a Shimano Deore 12-speed drivetrain, we became curious about the benefits of higher-end options. So, we partnered with Jenson USA, who generously provided us with the full range of Shimano drivetrains: Deore, SLX, XT, and XTR. Our goal was to test, review, and determine which one offers the best value. The only condition was that we would give away the XTR groupset at the end of testing.

Installation Simplicity

Installing and adjusting Shimano MTB drivetrains stands out for its user-friendliness. Key features like the easy clutch disengagement and visible limit screw functionality make it straightforward. Additionally, all Shimano derailleurs feature a built-in B-Tension adjustment indicator on the derailleur cage, simplifying the setup process. However, one minor drawback is that Shimano's shifter bar clamps lack a hinge, requiring grip removal when switching levers, which may be a consideration for some.

Deore: Budget Champion

Let's start with the Deore, the drivetrain that came standard on the Polygon Siskiu T7. A complete Deore setup, including the cassette, derailleur, shifter, and chain, weighs 1,360 grams (3 pounds) and costs a mere $188. Over the course of six months, we rigorously tested this drivetrain, covering approximately 200-300 miles on challenging XC trails with frequent gear shifts. Surprisingly, the Deore drivetrain withstood our abuse and maintained its smooth shifting performance. Its resilience can be attributed to the all-metal construction of the derailleur, although it adds a bit of weight, it enhances durability, making it less prone to damage from minor falls and improper storage.

The Deore derailleur features Shimano's Shadow RD+ clutch, effectively eliminating chain slap and preventing chain drops. Moving on to the shifter, it offers reliable performance with grooved thumb pads for improved grip and an easy-to-adjust cable adjuster. While the lever action isn't as light as higher-end options, it still serves its purpose well. However, it lacks Shimano's Multi Release feature, which allows for two upshifts in one throw. The Deore cassette is constructed entirely of steel, with the seven largest cogs pinned to an aluminum spider. The Hyperglyde+ machining, consistent across Shimano's 12-speed range, ensures silky-smooth shifts even under moderate load. In summary, the Deore drivetrain may lack bells and whistles but delivers dependable performance.

SLX: A Marginal Upgrade

Moving on to the mid-tier option, the SLX drivetrain consists of a cassette, derailleur, chain, and shifter, weighing 1,250 grams (2.75 lbs) and costing $257.96. While it offers a 110-gram weight reduction compared to Deore, it comes with a $70 price increase. Much of this weight saving can be attributed to the use of aluminum on the largest 51-tooth cog in the cassette. The SLX derailleur features more machining but doesn't present a significant performance improvement over Deore.

The main upgrade offered by the SLX drivetrain is its chain with Shimano's Sil-Tec coating, reducing noise, friction, and extending chain life. In our testing, SLX did not offer a noticeable advantage over Deore. We initially expected it to be a significant upgrade, but the difference proved to be subtle and might go unnoticed by many riders.

XT: A Notable Step Up

A full XT drivetrain weighs 1,160 grams (2.5 lbs) and costs $395.96, offering a 200-gram weight reduction compared to Deore but at more than double the price. The primary weight-saving feature is the cassette, which includes an additional aluminum cog. The XT derailleur allows external clutch tension adjustment, making it slightly more versatile compared to Deore or SLX.

XT shines when it comes to the shifter. With a rubber pad on the lever and improved shift speed thanks to Shimano's Instant Release technology, it provides a noticeably enhanced experience. Shifting with XT is exceptionally smooth, offering virtually no auditory or mechanical feedback as you switch gears. The XT shifter also features Shimano's Multi Release system, allowing you to shift up two gears in one throw, which adds to the overall performance quality.

XT offers a compelling balance of performance and cost, making it an attractive choice for experienced riders seeking top-tier features at a more affordable price.

XTR: The Pinnacle of Performance

The XTR drivetrain, with a price tag of $889.96, is the flagship option. Weighing just 1,010 grams (2.3 lbs), it includes three aluminum cogs, five titanium cogs, and four steel cogs in the cassette. While the weight savings over XT is hard to notice, it certainly has an impressive appearance. The rest of the drivetrain components share similarities with XT, but with more exotic materials and machining to further reduce weight.

One notable difference is the increased audible feedback when shifting with XTR, which may be a preference for those who prefer a more tactile experience. The XTR derailleur cable features a polymer coating, reducing shifting friction beyond the standard Optislick coating found in the lower-tier models. The XTR chain features hollow pins, further reducing weight compared to the XT chain. While the lever action isn't noticeably lighter than XT, the XTR offers diminishing returns for its premium price.

Conclusion: Value Champions

In terms of value, there are two winners. Deore, priced at less than $200, rivals the performance of XTR, making it a solid choice for most recreational riders. SLX, while marginally better, may not be discernible in a blind test. XT, on the other hand, offers almost every feature of XTR at less than half the price, making it a great value for experienced riders looking for top-notch performance.

For those who want to build a Shimano drivetrain part by part, a combination of Deore cassette, Deore derailleur, SLX chain, and an XT shifter can deliver performance similar to XT at a more affordable price. Ultimately, the choice of drivetrain depends on individual preferences and budget constraints, but Shimano offers options that cater to a wide range of riders.