Since its release, the SRAM T-Type drivetrain has quickly become a force to be reckoned with and is now found on a vast majority of mid- to high-end mountain and gravel bikes. The technology has trickled down to the GX T-Type and S1000, too. Today, the US drivetrain giant has unveiled its next step in the Transmission story – Eagle 90, a drivetrain that brings the benefits of T-Type to cable-actuated shifting. I’ve been riding Eagle 90 for a few weeks now and here are my first impressions.

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The cable-actuated Eagle 90 drivetrain might share a lot of DNA with the Transmission ecosystem, but there are two main differences – the derailleur and the shifter. As a Transmission product, Eagle 90 carries many of the same values including greater strength and smooth shifting under load.

The derailleur uses a hangerless interface and Full Mount system that makes T-Type so distinguishable. Binning the mech hanger in favour of the direct mount is said to make the derailleur much stronger, which reduces the chance of improper adjustment regardless of the frame. As before, it also allows the mech to rotate backward under impact, saving it from severe damage should the worst happen.

2025 sram eagle mount close.jpg, by Liam Mercer

Although SRAM is certain that the Eagle 90 mech is so resilient you shouldn’t need to rebuild it, a complete suite of replacement parts is available. It also requires only two tools to disassemble.

Catering to both regular mountain bike and e-MTB users, there are two shifters on offer. One is a single-click shifter that restricts downshifts to one per push, and the other is a double-click shifter with two shifts per full lever push. The decision to limit the shifts per push here is to retain the best shift quality under load. All mechanical drivetrain users will be familiar with that huge crunch and significant loss of power as a chain slides over multiple cogs before settling on your chosen gear.

2025 sram eagle shifter.jpg, by Liam Mercer

The shifter follows the Stealth shape that SRAM introduced on its recent brakes. This Eagle 90 shifter sits closer to the bar, which looks mighty tidy, but also helps with cable routing for a cleaner finish. A neat touch is that there’s a Stealth dropper remote available for those who want a cohesive SRAM/Stealth cockpit.

Cool considerations are rife across the Eagle 90 drivetrain as the aluminium crankset is available in lengths from 175mm to 155mm, fitting right into current trends of short cranks – e-MTBers even get a 150mm crank. For this test, we’ve gone for the 165mm crank. Present are the removable chainring-specific bash guards protecting a stamped-steel chainring chosen for its durability. There is an alloy chainring available for the gram chasers out there.

2025 sram eagle crank.jpg, by Liam Mercer

As for the rest of the drivetrain, it’s mighty similar to GX T-Type using the same X-Sync profiled cassette with SRAM’s 520% range and a 55mm chain line. Eagle 90 also employs GX’s flattop chain.

For those interested in Eagle 70, that’s an OE drivetrain available on new bikes but replacement components will be available. For more details, check out the news story.

Moving on to the system weight, it’s very competitive at 1,764g without cables. That’s only 40-odd grams heavier than XX T-Type AXS and 40-ish grams lighter than Shimano XT but pricier at £655.

Expanding on pricing, a replacement crankset is £150, the shifter £50, the chainring £20, the mech £120, the chain £55, and the cassette will set you back £270. That’s ignoring e-MTB-specific options.

SRAM Eagle 90 Transmission - Ride impressions

First off, Eagle 90’s setup is incredibly straightforward but as there’s no motor nestled within the mech, it’s not able to guide the chain over the setup cog on the cassette without a bit of help. However, SRAM’s been clever here, placing a port underneath the parallelogram for a 4mm Allen key. Pushing the mech and chain into the setup cog by hand and shoving in the Allen key locks the mech in place, allowing for quick and easy b-tension adjustment.

2025 sram eagle mech align.jpg, by Liam Mercer

Other than that, if you’re already familiar with the T-Type setup procedure, it’s all the same and simple. Once the b-tension is sorted on the setup cog,  you hook up the cable and dial in the cable tension. Chain length is then determined via SRAM’s excellent guide, which can be found online.

Since well before its launch, I’ve been running GX Transmission without issue, so I’ve become accustomed to the shift quality it provides. Being honest, it was criticised for its slower and more methodical shift compared to traditional setups by me and other media. But importantly, SRAM has managed to take all of the good points of T-Type and bring them to a cable-actuated drivetrain, binning the need to recharge a battery every so often, which is liberating.

2025 sram eagle mech 1.jpg, by Liam Mercer

As the speed of Eagle 90’s shift isn’t restricted by the servo in the derailleur, shifting is a more prompt affair. It’s mega-responsive to inputs at the shifter, where the mech guides the chain from cog to cog with only a little lag as the chain waits for a shift ramp on the cassette. But as it moves over the cassette, it’s noticeably smooth, quiet and rather slick, only letting off a bit of a crack as the chain engages with the new gear. Additionally, Eagle 90 retains the T-Type performance when shifting under load on steep climbs with negligible backlash from the system.

Thanks to the fact that the system is cable-operated, Eagle 90 can drop into a higher gear after a rapid-fire push of the ‘harder’ button. Doing so encourages the chain to skip over unwanted gears, meaning the riders don’t have to wait for the mech to move from cog to cog, as with T-Type AXS, when sprinting. That is at the expense of smoothness, however.

Quietness is a key factor here, as another criticism of the GX T-Type and some of the other Transmission models is that it doesn’t do the absolute best job of damping chainslap, so it can get rather raucous when descending rougher terrain. However, with Eagle 90, the clutch built into this new mech has managed to keep the chain taught as it flaps about. 

2025 sram eagle chainring 2.jpg, by Liam Mercer

An area where non-T-Type users will likely find fault is that the shifter allows only two downshifts per push, rather than a fistful of gears. As a result of that restriction, Eagle 90 shifts effortlessly under load. Single shifts during technical climbs remain smooth without any dip in power transfer, while dual shifts may be a little more vocal as they settle into gear and there may be a small break in power transfer. But even during double-shifts, the chain engages with each cog before reaching the desired gear, which is where Eagle 90 and any T-Type drivetrain achieves its smooth and near-uninterrupted shifts under power.

Where SRAM’s Pod shifter is a love/hate affair that was remedied to a point by the rocker upgrade, the new Stealth shifter is very likely to win folk over. The shape of each lever isn’t too dissimilar from those on SRAM’s regular mechanical drivetrains, and it’s certainly no bad thing. Generally, itrequires reasonably light action to activate the levers to initiate a shift. Clicks feel purposeful, and the whole system is very responsive.

2025 sram eagle shifter 1.jpg, by Liam Mercer

Admittedly, I’ve only put around 40 to 50km on Eagle 90 but so far, so good. I’m yet to find any flaws other than the extra care and adjustment of a cable-operated drivetrain. I would say that the stamped steel chainring is unnecessarily weighty, at 151g, without bash guards, but this can be upgraded. My favourite, the £40 Unite Components oval chainring weighs 60g, for example. 

What’s impressive is that, so far, SRAM has managed to bring the main characteristics of its Transmission drivetrains and accurately transfer them to a cable-operated system. 

• www.sram.com

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