SRAM’s Transmission drivetrain represents one of the biggest innovations in bike tech of recent years, but there’s a catch.
The direct-mount rear derailleur, which attaches, well, directly to the rear axle, requires your frame to be compatible with SRAM’s Universal Derailleur Hanger standard. It’s UDH that opens up compatibility between your bike and SRAM’s growing line-up of Transmission drivetrains.
As you might expect, some smart minds out there are seeing that compatibility conundrum as an upgrade opportunity, not a barrier, and that’s the case for Colorado-based upstart, Biggie Components.
As reported in James Huang’s N-1 Bikes newsletter, Biggie Components has developed a CNC-machined UDH conversion kit, specifically for Yeti frames, as well as the Revel Ranger (with the use of an additional spacer). It's a small spacer for the dropout that opens up Transmission compatibility.
According to Biggie Components, the Yeti T-Type Adapter, designed to fit non-UDH Yeti mountain bikes manufactured between 2019-2023, “does not require any frame modifications, no special tools, and is easily reversible”.
The benefit here, of course, is that, should you own a Yeti designed before the brand – also based in Colorado – adopted UDH, you can upgrade to a SRAM Transmission drivetrain without needing to buy a whole new frame.
Yes, you’ll need to purchase the relevant Transmission parts – cassette, derailleur, chain, chainring, axle and AXS controller – but we’re big fans of innovative solutions that help riders upgrade their current bikes with the latest components.
We’ve long been fans of the likes of Ratio Components, which offers a range of smart conversion and upgrade kits. Last summer, it released an option that enables you to convert your bike to a 1x SRAM XPLR drivetrain without replacing your rear derailleur.
According to Huang, Biggie Components’ Reid Fletcher developed the adaptor after buying a Yeti, which was then incompatible with Transmission when the latest SRAM Eagle drivetrain launched in March 2023.
There’s a much bigger market of potential Transmission upgraders out there than Yeti owners, of course. Fletcher has measured “all the major brands of bikes to check [the] plausibility” of developing adaptors, but has stuck with Yeti because of their “simplicity”, Huang reports. “Most other bikes you need to mill the frame which isn’t possible for most people; the existing hole in the frame is too small,” Fletcher adds. Will another company take up the challenge? Watch this space.
As for SRAM, after launching the top-tier XX Eagle Transmission drivetrain in 2023 – a groupset our senior technical editor, Alex Evans, awarded five stars in his review – the components giant followed up by introducing more affordable, GX Eagle parts. Alex filed his review of SRAM GX Eagle AXS Transmission in November, following 2,300km of testing.
The infiltration of Transmission across the SRAM range continued with the release of the new SRAM Red XPLR AXS groupset last year, with a direct-mount rear derailleur. As a result, we’ve seen an increasing number of gravel bike – and road bike – brands incorporate the Universal Derailleur Hanger standard into their latest designs.
Could SRAM release a direct-mount road bike derailleur in the future? Well, seeing as the latest flagship SRAM Red AXS road groupset was only released in 2024, with a traditional derailleur design that doesn’t require the Universal Derailleur Hanger, we’d say it’s a little while off yet.
For mountain bikers, however, SRAM Transmission is here, and it’s here to stay, so hats off to Biggie Components for opening up an upgrade option for Yeti owners.
