SRAM is truly bringing direct mount derailleurs to the masses, with complete Eagle 90 T-Type groupsets costing $670. Not only that, they are 100% battery free, so you can finally ditch the little solar panel on your top tube keeping your derailleur charged. It feels like consumer's wishes have been granted with these two new mechanically actuated Transmission groupsets, so let’s dig into the details and explain why we’re so excited about the Eagle 90 and Eagle 70 Transmissions.

SRAM is promising the best mechanical shifting we’ve ever seen with their mechanical transmissions, using much of the same technology found in their higher end AXS transmissions. The two groupsets, 90 and 70, use a new naming convention that we haven’t seen from SRAM before, and have some key differences between them. To give some context, the 90 groupset is comparable to the GX level, and the 70 groupset is comparable to the NX level. Generally, there is more metal used throughout the 90 groupset, while the 70 gets more affordable composite in some key areas. Overall, the 90 groupset is higher quality, more robust, and lighter than the 70 groupset. Riders can mix and match all T-Type components, so if you’re rocking an AXS Transmission and want to go mechanical, all you need to buy is a derailleur and a shifter.

Let’s take a closer look at each individual component in both groupsets.

The Eagle 90 derailleur has a silver and black colorway, while the Eagle 70 derailleur is clad in black from head to toe. Like other high end derailleurs from SRAM, the Eagle 90 derailleur uses a Roller Bearing Clutch, but the Eagle 70 derailleur uses a Drag Spring Damper to control the forces going through the derailleur. The Drag Spring Damper has been used on other affordable derailleurs from SRAM, and is lighter but less powerful than the Roller Bearing Clutch used on the Eagle 90 derailleur.

SRAM’s XD driver was initially debuted to accommodate a 10t, something that wasn’t possible with an HG driver. Those constraints are now lifted by the 55mm chainline, rather than the 52mm chainline on SRAM’s previous Eagle drivetrains. With those 3 extra millimeters, there’s enough room for the 10t cog on the HG driver. Even though it’s cheaper and uses a different mounting interface, you can expect the same great shifting performance with the Eagle 70 cassette as all other SRAM T-Type groupsets.

The all new SRAM Eagle 70 Flattop Chain is the most budget oriented flat topped T-Type chain to date, and it uses solid pins through every link. The Eagle 90 groupset does not get a new chain, and instead uses the popular GX T-Type chain. You can use any T-Type chain with either of these groupsets, and the new, more affordable Eagle 70 Flattop Chain is also compatible with all of the pricey AXS Transmissions. I expect there will be lots of riders experimenting with mixing and matching chains across these groupsets, potentially even using the pricy high end X0 and XX chains on these mechanical groupsets.

Back to new products, we have a new Eagle 90 crankset and Eagle 70 crankset to go with these groupsets. Short cranks have become more and more mainstream recently, and SRAM has heard our cries for cranks shorter than 165mm. The forged aluminum Eagle 90 Crankset is available in 155, 160, 165, 170, and 175mm lengths, and is a sleek, sturdy answer to what many riders are looking for in a crankset. The aluminum Eagle 70 cranks are only available in 165, 170, and 175mm lengths, and both cranksets use a DUB Wide spindle for a 55mm chainline. Both cranks use a stamped steel chainring, available in 30, 32, or 34t versions, all with +3mm offsets and are compatible with GX and X0 bashguards. They differ in their chainring mounting; the 70 crankset uses a 3 bolt chainring, while the 90 crankset uses the newer 8 bolt pattern. That means Eagle 70 chainrings are compatible with all previous generation Eagle cranksets, and Eagle 90 chainrings are compatible with all current T-Type groupsets.

Groupsets for Eagle 90 will be available with everything we just described in a neat kit that takes the guesswork out of piecing everything together. Eagle 70 won’t have complete groupsets available aftermarket, and instead components will be available individually. There are standard Eagle 90 groupsets with crank length options between 165mm and 175mm. The shorter 155 and 160mm Eagle 90 cranks are only going to be available individually, and I presume lots of riders with GX and X0 Transmissions who have wanted the shorter cranks will take advantage of these new offerings.

SRAM has worked hard to create an ecosystem, and all of their Transmission components are cross compatible with each other. That means if you currently have an AXS Transmission groupset, you can purchase just a derailleur and a shifter to convert back to cables. Or if you want to use a longer lasting but heavier Eagle 90 chainring with your XX Transmission, no problem!

The freedom you get with cross compatibility of parts in the T-Type groupsets is pretty great, and it gives so much opportunity to customize your drivetrain and prioritize different components. You want an upgraded derailleur but want to save some money on your cassette? Great, you can do exactly that. Love you GX or 90 Transmission but want the chain to last longer? Just get an X0 chain and you’re good to go.

Installing the Eagle 90 Transmission takes inspiration from an AXS Transmission and a mechanical Eagle drivetrain, and has some unique steps that no other drivetrain setup includes. This isn’t going to be a “how-to install Eagle 90 Transmission” article, as SRAM has a thorough video detailing all the steps perfectly. You’ll still follow the same Prepare, Hang, and Tighten steps used in AXS Transmission installation, followed by an additional Route step. The Tighten step is quite unique with the Eagle 90 derailleur. Just like their AXS counterparts, mechanical Transmission derailleurs are devoid of any adjustments. That means no limit screws or b-tension adjustments anywhere on the derailleur, and tightening the derailleur correctly is how you’ll get the proper b-tension.

SRAM promised big things with their AXS Transmission when it launched. The Dream Delivered was their tagline, aiming to take riders to shifting Nirvana as you beep boop through the gears. Many riders found it to be true, as the direct mount derailleurs welcomed a poorly timed shift as you muscled your way through a technical climb. While the performance was welcomed, myself and many others wondered where the magic came from. Are the robots methodically parsing through the cassette? Optimally placing the chain to eliminate those terrible pops and bangs we expect from negligent shifting? Eagle 90 proves that’s not the case, and delivers the same precision as its AXS counterparts without the added price, weight, or battery.

At the risk of sounding paid off by SRAM, I will say that Eagle 90 is my dream delivered. The shifting performance of the Eagle 90 Transmission is just amazing, and the simplicity of a cable connecting my shifter and derailleur is something I’ve missed.

Ergonomically, the Eagle 90 shifter paddles are located in familiar positions, and both are only accessible with your thumb. With a cupped and paddly shape, the upshift lever is more comfortable to me compared to the previous mechanical Eagle shifters, while the downshift lever remains relatively unchanged. Upshifts are delivered one at a time, and downshifts are either one or two gears per click with this non E-MTB shifter. Stealth routing parallel to the bar makes for incredibly clean cable routing with both Mavens and TRP EVO Pro brakes, and doesn’t add any clutter to your cockpit compared to a wireless setup. SRAM’s new cable management clip helps the cause, and I was very impressed by how tidy everything is with the Stealth routing.

What I’m looking for in a drivetrain is pretty simple, and it’s the same thing I’m looking for from any component. Invisibility is my number one priority, and any component I have to think about while on or off the bike is not optimal. That means the less I have to think about my shifting, the better, and while you can’t be completely brainless with the Eagle 90 Transmission, it’s the most invisible drivetrain I’ve gotten to use. You don’t need to think about charging batteries, you don’t need to be as particular about when you shift, and the paddles are intuitively placed. Eagle 90 prefers to be loaded while shifting, and if you’re used to easing up on the pedals to coax the chain to the next gear, you’ll have to re-wire your brain to just pedal through the shift.

On the descents, chainslap is slightly quieter than on the AXS Transmission, and is overall a very quiet drivetrain on the way down. It’s not as quiet as SRAM’s 11 speed drivetrains of old, but their Roller Bearing Clutch handles the long cage admirably. Until we finally cross the divide to belt driven gear boxes, there will always be chainslap, with the frame being the biggest factor in how loud your drivetrain is. Some bikes like the Specialized Stumpjumper 15 or Transition Sentinel have very effective chainstay protectors, doing a great job of quieting everything down. I recently tried an Ochain for the first time, and that also quieted things down further, but I’m getting distracted.

In case I haven’t made this clear already, I will choose the mechanical Eagle 90 Transmission over any level of AXS Transmission any day of the week, and I’ll explain why. AXS is seen as the pinnacle of performance, but I don’t think that I would recommend it to anyone over an Eagle 90 Transmission. It comes down to a few factors.

First is pretty obvious, and it’s freedom from batteries. AXS Transmissions have a rechargeable battery in the derailleur, and a replaceable battery in the shifter. Battery management isn’t the end of the world, and I typically have to charge my AXS derailleur battery about once a week, potentially more in the summer time. I have certainly cut rides short because the red light started flashing, and getting caught with a dead battery while ten miles from the car is worth avoiding.

 A quirk of the AXS Transmissions is their shifting speed. Getting from one end of the cassette to the other isn’t often an all out drag race, but I know everyone has come around a corner and wished they were about 6 gears over on their cassette. In these moments, AXS Transmissions will give you those first two gears very quickly, but then will slowly give you one or two a second no matter how quickly you hit the button, really slowing down your chain from getting to the correct gear. SRAM says this is to make each shift higher quality, allowing the chain to hit those shift ramps on the cassette every time and maintain complete engagement, but the Eagle 90 Transmission doesn’t play by those rules. You get those shifts right when you hit the trigger, and it’s easier to get into the right gear faster with the mechanical Eagle 90 Transmission.

Lastly, another obvious difference is the price. Barrier to entry with the Eagle 90 Transmission is far lower, and the groupset costs $670, compared to a GX Transmission costing $1099. While these direct mount derailleurs are strong, they still break, and the mechanical Eagle 90 derailleur is about the third the price of the cheapest AXS derailleur. Breaking a derailleur shouldn’t also break the bank, and Eagle 90’s price point is far more manageable than any wireless option.

SRAM took their time with the Eagle 90 and Eagle 70 Transmissions, and they listened to what the public asked for, bringing the performance of Transmission to a much lower price point. I believe Eagle 90 is currently the best drivetrain available, and I expect to see it widespread across all genres of bikes, from cross country to enduro to ebikes. When paired with SRAM’s new dropper remote and any stealth brakes, your cockpit will reach levels of aerodynamics previously thought to be impossible on a battery free mountain bike. I have no reservations in recommending the Eagle 90 to all riders with a UDH compatible frame interested in the best shifting available.

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