SRAM X0 EAGLE TRANSMISSION GROUPSET REVIEW

Words by Max Ritter  |  Photos by Dusten Ryen

We’ve put miles on half a dozen SRAM Transmission drivetrains for this X0 Eagle Transmission review and had a lot of fun doing it. There are generally two types of product launches in the bike industry: the ones that trickle in quietly under the radar; and the ones that scream loudly claiming a “revolution” in the industry. SRAM’s newest drivetrain – the all-electronic X0 Eagle Transmission – definitely falls into the latter category. When it first launched this summer, we were treated to all kinds of new marketing terms, videos of riders and influencers attempting to destroy the derailleur with blunt objects, and gasps of dismay that there was yet another non-backwards-compatible chain standard now on the market. The horror! But electronic shifting in and of itself isn’t new, so how does SRAM’s latest drivetrain actually compare?

THE LAB

On the surface, SRAM’s X0 Eagle Transmission may look like any old electronic drivetrain – it has all of the components you’d expect. But take a closer look, and you’ll notice refinements on every level: a new derailleur mount and derailleur tech; a new type of chain and cassette; redesigned cranks with a creative bashguard, and even a new shifter pod. All these updates fall under a new standard that SRAM calls T-Type.

First off, SRAM decided to nix the derailleur hanger, opting for a direct mount to the frame in a system they call Full Mount. When they recently smartly introduced the SRAM Universal Derailleur Hanger (UDH) standard, it seemed like the decades-long struggle to find spare hangers for your bike frame would finally be put to bed. And it pretty much did. But now, we’ve learned the ulterior motive was to create a standard mount for the new T-Type derailleur, found across the entire new Eagle Transmission line (GX, X0, XX, and XX SL). It clamps directly to the rear axle threads from both sides, promising increased stiffness and more reliable and predictable shifting, as well as ensuring the derailleur can rotate backwards in case of an impact to keep it better protected. Ok, so that’s not entirely revolutionary, but some of the tech inside like the self-disengaging Overload Clutch, a skid plate, and the fact that the entire derailleur is serviceable seems like a step in the right direction. I’m always a fan of parts that are meant not just to last, but that can be serviced in my own garage when stuff inevitably blows up. A neat extra feature on the XX and XX SL derailleurs is the Magic Wheel lower pulley, which has an outer ring that can rotate independently of the center section in case of an object jamming it. The derailleur weighs 466g including the AXS battery.

With an updated derailleur comes a new 10-52t cassette, complete with a refined X-Sync tooth profile optimized for shifting under load. SRAM has paid particular attention to the shift routes to keep the chain engaged onto two cogs simultaneously, seeking a smoother shift that doesn’t momentarily lose power transfer. They claim this not only to deliver a better shift, but to reduce wear for improved durability too. We’re still using the good old XD driver here, so this will fit on any existing SRAM-compatible rear wheel. At a claimed 376g, it’s a touch heavier than the older X01 12-speed cassette.

SRAM says the new X0 T-type flattop chain is their strongest ever, with solid pins to make it eBike approved. There’s a Dark Polar finish to give it a special look, with an electroless nickel plating and PVD coating to resist corrosion and wear. T-Type components are all cross-compatible, however it is not backwards compatible with older SRAM mtb stuff.

The new aluminum X0 T-Type crankset and chainring features a clever integrated bash guard that allows the rider to customize which position (one sided, dual-sided or removed) to run the guard in. The cranks are available in 165, 170, and 175mm options and can accommodate a Quarq power meter in the spindle. The engineered cutout shaves some weight, letting the crank arms carry what SRAM claims to be the lightest alloy crank weight, though the crank system ends up slightly heavier than the older version at 685g. They are compatible with all SRAM DUB bottom brackets.

Finally, SRAM completely redesigned the AXS shifter pod. With a flippable design, it can be run on either side, in any orientation. At 50 grams, it is lighter than the existing AXS shifter, and offers a wider range of position adjustment, allowing you to fine-tune exactly where the buttons are in relation to your brakes and grips. Like the older version, the buttons can be programmed through the SRAM AXS mobile app.

The full X0 Eagle AXS Transmission setup can be purchased for $1,599 aftermarket.

THE DIRT

With a recent move to the PNW, this summer has been filled with many pedal-powered trail rides, exploring miles of singletrack across Washington, Oregon, and BC. I tested SRAM’s new X0 Eagle Transmission aboard Yeti’s new SB135 LR, pretty much the perfect bike for that job. Since May, I’ve likely put over 500 miles on the drivetrain, in all manner of conditions. At the Wolf Den HQ and even with Robert over in the UK, we’ve had three other riders putting miles on the system aboard everything from bike park-ready enduro sleds to eMTBs with chain snapping torque.

I will be completely honest and say that I’ve never been a devotee to electronic shifting, whether its AXS or Di2. I simply just don’t see the point on a mountain bike. For my tastes, there’s absolutely nothing wrong with a shifter cable. They’re cheap, predictable, easy to fix, and you never have to remember to charge them. However, I think the refinements of SRAM’s newest generation of AXS might give this drivetrain…I mean Transmission…a chance in my book.

Setup on a compatible frame is pretty darn easy, though somewhat different than other drivetrains – bolt everything to your bike, measure your chain following SRAM’s guide, make sure the derailleur is lined up with the small mark on the back, and let the AXS app do all the dirty work. SRAM says you should never have to adjust it after install, which proved to be true in this case, though you can micro adjust the mech in case something goes awry.

First things first, the system shifts REALLY well. As (heavily) advertised, the Transmission works phenomenally well under load. Even after months of heavy riding, the jump between gears under hard pedaling is almost imperceptible. Jumping back on a bike with a non-Transmission drivetrain is really where you’ll notice. On a fire road climb, it’s not really a big deal, but on technical climbs, where precise pedal strokes and power are necessary, it’s really nice to learn to trust a drivetrain not to skip or blow up every time you put down the hammer. The shifting feels to be a little slower – or even a lot slower – at times, especially when jumping multiple gears. But it’s so smooth that you can just keep pedaling right on through, with consistent power transfer to your wheel. Some of our other testers, especially those who were quickly shifting from descents to super steep climbs where several shifts were required, noticed some hard shifting noises due to the high amount of torque – especially on eBikes – but we never had a mis-shift or chain issue. So, although it is slower and can still make some ugly sounds, it never failed us.

Next, we’ll move into the ergonomics of the new shifter pod. At first some of the crew were not fans, but after having spent more time and adjusting them a bit, they have grown on almost all of us. Having the ability to move the shifter pod more easily to where you want it allows for a much more comfortable cockpit. I think it is a huge improvement over the first and second generation AXS shifters. I have thick fingers, and I found that the buttons were a good size to not accidentally press the wrong one.

An added perk of the SRAM T-Type drivetrain is that airline travel with a Transmission-equipped bike is a much cleaner affair. With the rear wheel off, the derailleur folds up neatly into itself, negating the need to remove it and risk bending it when putting a bike in a travel bag. There’s also no need to worry about kinking cable housing when removing handlebars. Pop the AXS battery off (and into your carry-on) and you’re good to go.

The Wolf’s Last Word

Now for the fun part. Is this drivetrain worth its whopping $1,600 price tag? That’s over twice as much as the existing mechanical version of the X01 drivetrain, and over four times more expensive than the $360 Shimano XT LinkGlide drivetrain…FOUR TIMES! So, is that eye watering price tag worth it? That’s going to be up to each individual rider, their budget and what they want out of the ride. For some of our staff, there’s no way we could justify spending that sort of money on a drivetrain when other more affordable options that perform under heavy load exist. For others who have the cash or want the pinnacle of performance, it could be worth investing in, as it provides one of the best user experiences out there right now.

Innovation has always come at a price, and this is no different. SRAM’s newest mountain bike drivetrain, the all-electronic X0 Eagle Transmission, falls into the innovation category, but does it actually change everything? Not exactly. It does take something so ingrained in our riding (pressing a handlebar-mounted lever to shift gears) and refines the interface and experience to the point where the reaction can truly become an afterthought. Ultimately, you’re still pushing a button at the handlebar and a (slightly less) vulnerable, externally mounted derailleur is moving a chain up or down a cassette.

No matter what side of the argument you’re on, there is no denying SRAM took the age-old rear derailleur and seriously re-thought how shifting should work on your bike, refining a lot of the limitations and performance. This new product shifts better under load, is usually smoother, can be rebuilt in most cases of damage and is more durable than ever before. No cables, two simple buttons, and a rechargeable battery is all that it takes. It’s pretty damn good, but you have to pay for the privilege.

Max’s Personal Impression
It sure does work pretty well, and I haven’t found reliability issues even after months and many miles of riding. I can see it giving a racer the edge they need on a sharp climb in the middle of an enduro stage or on mile 50 of an XC epic, but at nearly twice the cost of a “regular” drivetrain, I don’t know if it will replace my tried-and-true mechanical drivetrain just yet. I’ll deal with the shifting issues for now. 

Price: $1,599
Website: SRAM.com