SRAM Eagle 90 Transmission meets the Sonder Cortex – Mechanical is alive

Sonder Cortex meets the SRAM Eagle 90 Transmission Groupset. SRAM breathes new life into their mechanical groupset with plenty of trickle down benefits from Eagle AXS

Our Sonder Cortex full suspension trail bike now comes specced with SRAM’s brand new Eagle 90 Transmission mechanical groupset. Available to order today - yup that's today - the same day it is being released to the world.

We took the first Sonder Cortex to be built with the new SRAM Eagle 90 Transmission groupset on a road trip to the Lake District. Remote, rugged, steep and beautiful - we couldn't think of a better playground for it.

The Cortex is the first bike in the Sonder range to have the Eagle 90 groupset but our other UDH compatible frames will be added soon.

So what's new to get Sonder riders excited?

Clean, strong, easy to set up, and built to be ridden hard.

Our proven trail slayer— Cortex has 140mm travel up front, 135mm at the rear, Horst link suspension and geometry that wants to push you harder, faster for longer - and now fitted out with SRAM Eagle 90.

Let's start with the derailleur. And what do you know, it appears mechanical is far from dead, it has had a Full Mount resurrection. Instead of attaching to a derailleur hanger it clamps around both side of the frame. This strong and precise connection eliminates variance and improper adjustment. It is also designed to protect your derailleur by allowing it to rotate backwards on impact. The hangerless Full Mount interface means no more derailleur hanger faff and fewer trail-side tantrums when you whack something. That’s proper peace of mind for big mountain epics.

Eagle 90 feels incredibly easy to install, it is rebuildable, reliable, affordable, and promises to deliver the world’s best mechanical shifting. That might not be important to you straight out of the box, but offers some hope should you fall foul of a mechanical out on the trail. Anything that reduces the chance of mechanical failure on the trail gets a big thumbs up from us.

We didn't have to test this, but we were impressed by the precise mechanical shifting. The SRAM engineers have rethought from the ground up their single-click and double-click shifters. If you are a rider who attaches bike luggage to your bars, you will appreciate how the cables run satisfyingly parallel to the bars. Depending on your ride with a wide 520% range from the GX T-Type cassette you will make short work of steep mountain sides.

T-What? T-Type is SRAM’s latest and greatest drivetrain standard. We first saw it with their wireless Eagle Transmission lineup but it is now trickling down into the Eagle 90 mechanical world too. That is good news for riders looking to upgrade or for those starting on their SRAM journey from scratch. Let's recap some of the benefits that you are going to see on this Sonder Cortex SRAM Eagle 90 build.

Hangerless Design (Full Mount)

• Instead of using a traditional derailleur hanger, T-Type mechs bolt directly to the frame at the wheel axle via what SRAM calls the Full Mount interface. The frame still needs to be UDH compatible, but it removes the need for a UDH hanger.
• This makes the derailleur way stronger and more secure. It also helps it shrug off hits better, because it can pivot backwards instead of snapping clean off like a hanger would.

Perfect Chainline and Setup

• SRAM designed the chainring, crankset, cassette and mech all together as one complete system. That means better alignment, smoother shifting, and super simple setup—there’s even a “Setup Cog” on the cassette to get it dialled in fast.
• This standardises everything, so you’re not bodging adjustments or dealing with compatibility issues like in the good old days.

Built to Be Rebuilt

• T-Type mechs (including the Eagle 90) are designed to be taken apart and serviced. You can replace worn-out links, pulleys, even the skid plate. We like the direction SRAM is taking here.

Works with Flat-Top Chains

• T-Type uses the same beefy flat-top chain as their Transmission gear. It’s SRAM’s strongest ever. Seriously robust and even E-MTB approved.

Mechanical or Wireless

• The original T-Type stuff (GX, XO, XX, XX, SL) was all wireless AXS shifting.
• But Eagle 90 brings T-Type architecture to mechanical shifting. So you get all the frame interface and drivetrain goodness—but with classic cable-actuated feel.

Our takeaways are that the Eagle 90 is SRAMs strongest and most rebuildable mechanical derailleur yet. It delivers the top-end performance of AXS with a mechanical interface and without the premium of the electronics to reach more mortal pricing. Compatible with SRAMs UDH standard gives us faith it is an ecosystem riders can invest in with confidence for many years to come.

SRAMs Eagle 90 Transmission groupset is the perfect match for our Cortex 'grin-inducing' trail bike. Whether you’re threading tight singletrack, launching off roots or grinding through a Lake District climb, this rig is now even more bombproof, playful and primed to deliver.

Current Sonder bikes with UDH compatibility: Cortex, Evol, Signal Ti,Camino Al, Camino Ti and Sedona.