Maybe you’ve seen pictures of it in the wild. For the last year or so, photos surfaced of direct-mount, electronic drivetrains on downhill bikes. Rumors swirled of a new DH drivetrain project SRAM was working on, and those drivetrains looked an awful lot like Transmission.
Undoubtedly, these sneaky drivetrains were on the DH rigs of pros and industry testers. They were spotted at World Cup races and party laps at Whistler.
Well, today SRAM announces that the rumors are true with the release of the XX DH Transmission.
Comparing to Existing T-Type
For the most part, XX DH Transmission is essentially the same as the XX Eagle option SRAM released in 2023. However, some key factors distinguish this DH offering from XX Eagle.
First, it doesn’t fall in the Eagle lineup. Although the similarities are vast (just look at them side by side), “Eagle” is a distinct offering for SRAM. The label indicates 12-speed, 10-52t cassettes with the brand’s 520% gear range.
DH cassettes are 7-speed, pushing the new DH drivetrain out of the Eagle category. But, there are a few other differences that make the new XX DH Transmission distinctly DH.
Eagle XX T-Type uses carbon cranks, while the new XX DH sees aluminum. There is also a significant difference in crank length. Whereas XX T-Type cranks are offered in 165, 170, and 175mm lengths, DH XX cranks are significantly shorter. The new DH cranks range in 5mm increments from 150mm up to 165mm.
Spacing for the chainline is also different. DUB DH spacing is available for both boost and superboost rear ends, with a corresponding 56.5mm chainline. SRAM also offers the standard DUB Wide for a 55mm chainline. Which spacing you will need typically corresponds to your bottom bracket width–83mm or 73mm, respectively.
Also new is the XD SLIM freehub body option. Similar to the previous HG SLIM, this allows wider hub flanges and more symmetrical spoke tension due to better bracing angles. SRAM says that the older HG SLIM driver should work with the XD SLIM cassette. However, they recommend you check with the hub manufacturer.
Also, SRAM notes that the XD SLIM cassette isn’t compatible with a standard XD driver body, or vice versa.
DH XX Transmission Details
Derailleur
SRAM claims that the new XX DH T-Type derailleur is simply the strongest DH derailleur available. Same as Eagle T-Type, SRAM uses its full-mount design and stout cage, which we all found can take a considerable beating. It also uses SRAM’s Cassette Mapping to deliver precise shifting and constant engagement, resulting in uninterrupted power transfer.
Yes, this means shift away, even under load, as it doesn’t matter to Transmission. This will be crucial at the start, as racers will no longer need to hesitate, even for a fraction of a second, before hitting that next gear.
- Familiar install and pair via the standard AXS set-up and pairing procedure
- Replaceable skid plates, outer parallelogram link, and rebuildable thread-on cage assembly
- Inline Cage features a flat outboard surface for easy maintenance
- Type 4 damper results in very quiet operation through the roughest tracks
- T-Type chain compatibility only
- Aluminum
- 426g
- $700 (battery not included)
Crankset
SRAM drew inspiration from the established aluminum Transmission cranks but redesigned them from the ground up. Their goal was to develop best-in-class DH cranks that set a new strength-to-weight standard.
The new crankarms are stout, featuring machined surfaces in high-impact areas. And they start short and end fairly short, with lengths starting at 150mm and topping off at 165mm. The new cranks and chainrings are available with Ochain, which SRAM just acquired last year.
- DUB DH spindle for 56.5mm chainline, for either 157mm or 148mm rear hub spacing
- DUB Wide spindle for 55mm chainline, optimized for 148mm rear hub spacing
- Available in 150mm, 155mm, 160mm, and 165mm
- Aluminum
- ~701g (depending on length)
- $450
Cassette
Similar to the DH Transmission cranks, SRAM says the new XX DH cassette is the most robust cassette they’ve ever made. The 10-24t, 7-speed cassette features an X-Sync tooth profile and delivers precise gear changes at full power.
- Full X-Sync tooth profile for best-ever inboard and outboard shifting performance under load
- 7-speed, 10-24t
- T-Type, flattop chain compatibility only
- XD driver body, or gravity-specific XD SLIM driver body
- Steel
- 150g (XD) / 144g (XD SLIM)
- $500
Chainring
SRAM increased folding and impact resistance on the new XX DH T-Type chainring. This creates a chainring designed to withstand the most demanding downhill riding.
As with the cranks, the XX DH Transmission chainring was designed to work hand in hand with Ochain. The chainring uses a 104 BCD interface to easily integrate the product into the T-Type ecosystem. It is also cross-compatible with other Eagle Transmission components and backward compatible with older SRAM DH drivetrains.
- optimized for use with all Ochain spiders
- compatible with Eagle / DH drivetrains
- eMTB compatible
- 32t, 34t, 36t
- Aluminum
- ~43g (depending on size)
- $120
Flattop Chain
The same flattop chain found on the XX Eagle T-Type drivetrain is used on the XX DH Transmission drivetrain. Utilizing a hollow pin design, SRAM says this is the strongest chain they have ever made. SRAM also uses high-quality, durable chrome to extend the chain’s life.
One important note: this new drivetrain requires a T-Type, flattop chain. SRAM recommends using the XX or XO chain for best performance, but a GX chain or even the new Eagle 70 chain will work. However, SRAM states that the XX SL chain should not be used with the new XX DH drivetrain.
- Strongest SRAM chain ever
- Hollow pin
- Flattop profile
- 126 links
- Steel
- 247g
- $155
AXS Pod Ultimate
Wrapping up the SRAM XX DH Transmission drivetrain is the AXS Pod Ultimate controller. It’s light, features a completely new shape and ergonomics, and a huge range of adjustability. It has interchangeable touchpoints and a flippable design for mounting on the right or the left. Not to mention a bunch of customization in the AXS App.
- Interchangeable convex and concave touchpoint buttons
- Improved ergonomics and adjustability
- AXS App
- 50g
- $220
For right now, all SRAM is releasing is XX-level Transmission for DH bikes. If SRAM follows previous patterns, we expect to see XO and GX options shortly. Maybe even direct-mount mechanical DH? Check out all the details at sram.com.
