On the trail
So how does it all ride, right? Before heading to the launch I'd had about a dozen hours on the XTR M9100 12-speed group set, and my immediate thoughts were that there was very little difference when riding a Shimano Deore XT equipped Santa Cruz High Tower.
So much of the same features from the XTR 12-speed group have moved to the new Deore XT, that it really seems like the only things you give up are a few options on spec and some weight. About 350g all up over the whole group set, and much of this is in the cranks and rear cassette.


The beauty of riding trails blind in Bellingham was how much we all got to put the group sets under pressure. The trails are steep, both up and down, so we were often grabbing plenty of brake, or shifting under heavy load when faced with a pinch climb that was hidden by the thick trees. The trails were awesome, and the components didn't hold anyone back.
One thing that has really made itself noticeable is how quietly the group sets run. This is especially noticeable on the XTR M9100 thanks to the full SilTec coated chain (it has a dampening characteristic as well), but also on Deore XT. The tooth profiles and chain shapes mesh so well that they stay engaged and bounce very little. It's also the work done here that makes the shifting so smooth. There were no jumping gears on climbs no matter how late anyone forced a shift – and trust me we were all trying.


The action at the shift lever is also much improved, with a far lighter shift actuation. The 10-51 cassette doesn't leave the largest jump in teeth for the move to the 51 either, so the shift feel is really consistent all the way through. The last shift is actually super light, which is nice as when you're reaching for the 51t sprocket things usually aren't comfortable – so at least the shift is.
I believe the updated hub design with a faster engagement is part of what helps for chain security and quiet running as well. Shimano admitted that their silent running hub did have to be shelved for now, but at speed the new hubs are near quiet anyway – but they make a cool buzz at low speeds in the carpark. With less freeplay in the freehub, I find it makes for a more stable drivetrain with less chainslap. This is anecdotal and based on riding a wide variety of hubs, with engagements from 20 degrees through to 1.5 degrees. The faster engaging hubs have always had a more stable drivetrain – and that's something gained with Shimano's latest hub design.


Due to feedback from riders saying they felt the brakes felt a bit too on or off, Shimano changed the lever feel for modulation. I have always loved the Shimano brake levers with the ServoWave action and the SLX, Deore XT and XTR M9120 levers all have that. The blade is a little taller for a better feel and the stiffness at the lever thanks to the new clamp is immediately noticeable. The XTR M9100 lever doesn't seem have the same power or lever feel but if you're chasing a cross-country or marathon specific race setup then this is the choice for the weight advantages. I've taken to running a 180mm front rotor on my XC bike with an M9100 group set and that way I have all the stopping power I need.
Should I upgrade?
That's the big question isn't it. If you have always preferred Shimano group sets then you will really appreciate the new 12-speed groups, no matter what budget you're coming in at. Having owned bikes with the last 6 versions of XTR, and the last 3 versions of XT, and a couple of versions of SLX there is no doubt in my mind that the new group sets are a big leap forward. It's clear that having wide range 1x group sets from Shimano is a big part of it, but having the range of brakes, new freehub designs and parts interchangeability to tune where you want to invest in lower weight or higher performance is a big bonus.
Shimano's 11-speed groups made an upgrade from 10-speed a little easier as they stuck with their splined freehub design. The Microspline freehub is a bit of a catch as it means some riders can buy a new freehub, but many will need a new rear hub and wheel build, or maybe a whole wheel or wheel set.


As bike designs change this is possibly inevitable, and I think if you have been waiting for Shimano to have a widely available 12-speed option – it's here and it is time to jump in. Reading over the differences it seems subtle, but how it works on the trail and under pressure is where the true differences lie. Shimano did come to 12-speed a little late, and XTR M9100 was pretty thin on the ground at first, but with three group sets now out in the wild Shimano are right back at the top of their game.
With an XTR M9100 group set on long term test and an Deore XT M8100 group set being fitted up for long term review as you read this, we'll have more in-depth looks into the specific groups over the coming months.