Shimano Deore XT M8100 2020 drivetrain review

The Deore XT 2020 groupset is a confident update to an already great product. With its huge range and 12-speed gearing, it’s shifting is market-leading, yet it sits at a reasonable price for the level of performance and weight. In short, it's one of the best examples of mountain bike drivetrains.

I’ve had the XT groupset on a test bike for nearly nine months, and it's been nothing short of fantastic. It’s proven absolutely reliable, and the shifting now is as good as on day one despite some severe challenges – Scottish 24-hour racing, Sussex mud in the springtime, and the rocks of the Lake District in summer.

The shifting retains that smooth, yet solid feel that Shimano is known for, and the sculpted rear cassette is a masterclass in engineering – even when covered in grot, or under lazy shifting, it’s super reliable. It’s overall a more refined feel than the SLX I run on my own bike.

Chain life seems reasonable and wear has been minimal over nine months, though possibly a little higher than expected with 11 speed.

Those 12 speeds give you a 510% range on the 10-51 tooth cassette, and the small, two-tooth gaps between the first five keep it useful on techy climbs. This huge 51T can quite frankly feel like cheating, as you winch up climbs with little effort... I cleaned two tough ascents in my first month on XT M8100 that I’d struggled to manage before.

The top four – 33, 39, 45 and 51T – have much larger jumps, and work well at higher speeds without feeling gappy at all.

There is also a 10-45 tooth cassette, which racers may prefer, but the 10-51 is suited to more trail and general riding. I ran a mid-range 32T chainring at the front and, while I never ran out of easier gears, at times I missed a harder gear for flatter fire roads. Shimano does five chainrings from 28-36T in two-tooth increments, should you need to tweak that.

With the ten main cogs being steel and the two largest ones being aluminium, it weighs in at 470g. The whole lot sits on the new Micro Spline rear freehub created to accommodate the titchy 10t ring, and the pickup is quicker than before, but still not the quickest out there – sometimes I felt a slight lull or hesitation.

I absolutely love the shifter unit – for function, looks and detailing – and it carries the usual rapid trigger and a thumb paddle that sweeps up the block in around 2.5 lever pushes. There's no increase in effort over 11-speed and it’s surprisingly quick, while the rubber grippers give effective grip.

Threading new cables in is easy, and while using the mounting on the XT brake lever means adjustment is relatively limited, there's enough inboard-outboard movement to get it sitting exactly where you want it. Shimano also sells a separate band mount should you not want to run the XT brakes.

The rear derailleur is a chunky, solid affair that's taken plenty of knocks without complaint. The almost cartoonishly big jockey wheels keep things smooth by opening up the chain's approach angle to that huge 12 speed range, while the clutch mechanism is effective and – coupled with a urethane bumper – very quiet. The clutch can be switched off should you prefer.

The shaping keeps the mech tucked well out of the way and the whole thing clears mud pretty well, holding onto its very exact, certain feeling even under pressure in very muddy situations.

Elsewhere the cranks are the quiet stalwart – taking all the knocks, transferring the power and just getting on with it. The simple, no nonsense Hollowtech installation remains brilliant, but to nitpick, this generation looks a bit bland. At XT level and price, not everyone is going to appreciate the stealthy-to-the-point-of-unnoticeable styling.

The transparent helicopter tape helps with the inevitable shoe scuffing, but it feels like an afterthought and, as you can see from the pictures, is less than entirely effective. Again, it's a detail that doesn't quite sit right with the XT's level in the market – but then, when your only real complaints are aesthetic, you know in truth you're onto a winner.

With weight and price in mind, the full drivetrain as you see it reviewed here and rounded up to the nearer pound costs £542. All together it weighs in at 1,776g. That's 121g less than the new 12spd SLX with 175mm cranks at 1,897g which costs £350.

If I was speccing a frame build, XT would be my first choice for the drive chain. The wide range is genuinley useful, shifting is excellent in all conditions, and it's extremely reliable. Combine that performance with Shimano's typically great build quality and it's an extremely effective, reassuring chainset.