In March last year, SRAM unveiled its radical AXS T-Type Transmission, promising that the new drivetrain would bring unparalleled strength, durability, and precision shifting. It was to be the pinnacle of derailleur drivetrains – with a price-tag to match – meticulously designed to work in perfect harmony in the toughest of environments. But it was not without controversy, with riders bemoaning the high cost of individual parts and the loss of the sacrificial part between expensive frame and rear mech.

I’ve had the high-end XX T-Type Transmission fitted to a Specialized Turbo Levo since October 2022, and have clocked up 1,200km through two of the wettest and muddiest UK winters on record. So how has T-Type held up? What’s worked and what hasn’t? What are its strengths and weaknesses? And is upgrading worth the significant financial investment? Those are the questions I’ll answer in our latest video.

SRAM XX Eagle AXS Transmission combines a most robust mech with accurate, smooth shifts in every situation. But more robust doesn’t mean infallible.

If you haven’t read my first ride review of SRAM’s XX AXS T-Type Transmission, or Sean’s first ride review of the GX AXS T-Type, let me summarise my early impressions:

• I loved the fact you could bolt it to your bike and be up and running in just a few minutes. No need to faff around tuning the gears or threading cables through the frame; just pair the mech and shifters and away you go. The only crucial adjustment to make is the B-gap, which is a two-position setting. So you’re either right or wrong. No ambiguity.
• In a world where repairability is increasingly important, it’s great to see the AXS derailleur fully rebuildable. As the most expensive, and vulnerable part of the drivetrain, SRAM has put a lot of thought into making it user-friendly to strip-down, service, and repair.
• Neat features like the Magic Wheel lower pulley, and Overload Clutch, help protect the mech from knocks, scrapes, and errant sticks that are part and parcel of every ride.
• The shift quality is exceptionally solid, precise, and smooth. Whatever the gradient, however much power and torque you’re putting through the system, you’re treated to a perfect shift every time. It’s the best derailleur-based shifting I’ve ever used.
• I didn’t get on that well with the new shifter pods. Compared to the old AXS controller with the Rocker Paddle, I found it hard to find the right button in a hurry, particularly on rough ground. My thumb would bounce around on the buttons and occasionally shift more gears than I wanted to.
• Having crashed a few times onto the drive-side, it was great to see the XX mech undamaged during the early test period. However, the mech did get bent later on, after getting caught on a root in a narrow gully. This bent the lower cages outwards and required a replacement lower cage assembly – even though the clutch and pulleys were undamaged. The costs of this new part is an eye-watering £181. Which would sting if you’d just invested just under £2k in a new drivetrain. Repairing the mech is super easy, but the vulnerability of the lower cage – particularly on a mullet bike – is an issue all derailleur drivetrains suffer from, whether you have a burly direct frame mount or a soft, throw-away mech hanger.
• The shifting speed is much slower than old AXS across multiple gears. To get from one side of the block to another takes around 2-3 seconds with old AXS, while T-Type takes around 6-7 seconds. However, the result is less wear and no mangled shifts, so it’s a price worth paying.
• In terms of durability, my XX T-Type transmission has lasted extremely well. With 1,200km on the clock, of mostly winter riding, on an e-bike, the chain is registering a wear of less than 0.5%. Given that you should replace the chain at between 0.5% and 0.8% depending on how conscientious you are, I reckon you can expect to get 1,600km (1,000 miles) out of a chain and 3,000km out of a cassette.

The Magic Wheel in action – a clever feature given how easily the big pulley wheels and narrow-wide profile seems to pick up debris.

So a year on T-Type and it’s fair to say it’s been a mixed bag. I’ve loved the shifting performance, in fact I’d go as far as to say it’s the best derailleur-based shifting I’ve ever experienced. And it hasn’t missed a beat come rain or shine and through the worst of winter.

So far it’s proven impressively durable, and I haven’t yet reached a point where even the chain needs replacing. But I’ve also managed to bend the mech, which i think we’d all be happy to put down to bad luck. However, having to replace the whole cage assembly feels like a stretch when it’s only the two plates that are bent. And that makes it an expensive repair, even if it’s a fraction of the cost of a new mech.

The rear mech is fully rebuildable, but our bent cage required a complete lower cage assembly (top right), which costs a hefty £181.

To end this I think it’s worth going back to my original first ride from March. I concluded it by saying that, if the first XX1 Eagle was the final nail in the coffin of the front derailleur, then T-Type Transmission could be the kiss of death for broken mechs. Plainly that isn’t the case, and I think for that to happen mountain bikes will need a more radical solution, whether that’s doing away with the derailleur altogether through a gearbox, or tucking it inside the frame like the Supre Drive. In terms of derailleur systems though, I do think T-Type Transmission offers the best performance on the market.