New Wireless MTB Shifting - SRAM Transmission TESTED 40

SRAM has made their new wireless 12-speed mountain bike drivetrain public and it's called Transmission. We'll dive into the prices, different models, weights, features, installation process, and how SRAM Transmission performed out on the trail.

If it was ever a question as to why SRAM took it upon themselves to create a universalized derailleur hanger, we’ve got your answer. While the SRAM UDH interface is arguably one of the best standards to be accepted industry-wide in recent history, it is clear now that it was a mere Trojan Horse for the true plans behind its design. SRAM's new Transmission features a direct mount derailleur, new cranksets, and cassettes that utilize SRAM’s T Type chains.

SRAM Transmission Highlights

• Direct-mount derailleur interface
• Fully redesigned cassette
• T Type Chain interface
• Redesigned modular shift pods
• New cranksets with optional bashguard
• Individually replaceable parts
• E-Bike compatible crankset options
• New Stealth brake levers
• MSRP as Tested
  • XX T Type Eagle Transmission Powermeter AXS Groupset - $2299.00 USD
  • XX Rear Derailleur - $650
  • AXS POD Ultimate 2 Buton - $200
  • XX Crankset w/ Quarq Power Meter - $950
  • Cassette XS-1297 T Type Eagle - $550
  • Chain XX T Type HollowPin - $125

Compatibility

A mountain bike with a UDH interface is required to run Transmission, so if your frame and derailleur hanger isn't UDH-ready, Transmission won't work with your bike. And aside from the Pod controller and derailleur battery, Transmission is not backward-compatible with existing SRAM Eagle drivetrains, AXS or cable-actuated.

Transmission runs on a T Type chain interface which has a flat top, similar to their road group. The T Type chain is required for the drivetrain, as previous non-T Type Eagle chains will not work with Transmission. T Type chains can be used with previous Eagle components, however.

At the time of this article, the new crank and chainring interface uses 8 bolts, compared to the 3 on previous Eagle. That means until SRAM or aftermarket brands make compatible chainrings, you have to run SRAM cranks with Transmission.

The AXS Pod controller will work with previous Eagle AXS derailleurs or dropper posts. Previous Eagle AXS controllers will work with Transmission, too.

Don't do it. SRAM Non-T Type Eagle chain on Transmission drivetrain. Chain does not grab chainring securely.

SRAM Transmission Prices

SRAM Transmission comes in 3 groupsets, X0, XX and XX SL. We were sent an XX group to test out. Components in the 3 group levels differ in construction, materials or features which impact weight, price and performance.

All Prices are in US Dollars

Transmission Derailleur only, battery not included

• Transmission X0, $550
• Transmission XX, $650
• Transmission XX SL, $650

Transmission Cassette Prices

• X0 XG-1295 T Type - $400
• XX XS-1297 T Type - $550
• XX SL XS-1299 T Type - $600

Transmission Controller

• AXS Pod - $150
• AXS Pod Ultimate - $200

SRAM T Type Chain Prices

• X0 - $100
• XX - $125
• XX SL - $150

Transmission Dub Crankset Prices with chainrings

• X0 which are Q174, alloy, include dual guards and 32t chainring - $300
• XX - carbon, Q174 with dual guards and 32t chainring - $500
• XX SL - carbon, Q168 without guards and 34t chainring - $550

Chainring or spindle powermeter options are available.

SRAM Transmission Groupset Prices

Transmission groupsets include derailleur battery and charger

• X0 $1,599
• XX like the one we have for testing starts at $2,049
• And the XX SL group starts at $2,199

Weights

We weighed the Transmission XX components that we received as well as previous Eagle AXS X01 and cable-actuated X01 parts to compare for a ballpark of old vs new weights.

Derailleur weights

• Transmission XX with battery - 465g on our scale
• SRAM claimed weights for Transmission XX SL, XX and X0 - 440g, 465, 475g
• Since Transmission doesn't need a derailleur hanger, we included the UDH hanger weight for previous models
• Original AXS Eagle X01 with battery - 390g (no UDH), 417g (with UDH)
• Cable Eagle X01 - 287g (no UDH), 314g (with UDH)

Cassette weights

• SRAM Transmission XX 10-52t XS 1297 T Type - 379g on our scale
• SRAM claimed weights for Transmission XX SL, XX and X0 - 345, 380g and 380g
• Eagle X01 10-52t XG 1295 - 375g

Controller weights

• Transmission AXS Pod with Discrete Infinity Clamp - 47g
• Original AXS with Discrete Clamp - 86g
• Eagle X01 with cable, 124g without clamp (+11g for discrete clamp) or housing which should be considered in system weight

Chain Weights

We kept them in the cases to keep things clean. The XX case weight 42g.

• SRAM XX Eagle T Type, 126 links - 352g on our scale. SRAM claimed, 247g (for 108 link maybe? SRAM weight is 33g heavier than our scale w/o case)
• SRAM X01 Eagle, 126 Links - 296g on our scale

Crankset Weight

SRAM Eagle Transmission XX Crankset weight, 175mm length with dual bash guards

• 553g on our scale

SRAM did not have crankset weights available at this time and we didn’t have a previous Eagle crankset to weigh.

Transmission Overview

Derailleur

SRAM wanted Transmission to have fool-proof setup, easy maintenance, and unparalleled durability while being able to handle shifting under heavy load. The derailleur mounts around a bike’s rear axle with contact points on both sides of the frame. This ensures perfect alignment between derailleur and cassette on any bike. It has an alleged 600-pound breakaway force. Vital Tech Editor, Jonny Simonetti, who is 6'4", 220lbs. has walked on the derailleur countless times to highlight the durability. Like previous AXS, there is a breakaway clutch so the derailleur can move inboard on impact.

The new derailleur cage design incorporates some preventive measures to keep trailside objects from sucking into the lower pulley in the form of a longer lower guard. Should objects find their way into the lower pulley, the “Magic pulley'' found on XX and XX SL models allows for free movement through the use of a metal inner wheel and the plastic outer ring which glides along an internal track. Continuing with preventive measures, SRAM has studied which parts of a derailleur most regularly make contact with the trail and reinforced them with bash guards to prevent damage to key components. Additionally, these parts are all individually replaceable so consumers won’t be faced with the cost of a new derailleur in the event of a failure. On top of that, it allows for X0 derailleurs to be upgraded with XX or XX SL cages for either the addition of the Magic Pulley or for weight savings. Removal of the cage is tool-free. The cage is attached with a coarse thread that locks into place and clutch tension seems to hold a higher force than previous generation AXS derailleurs.

AXS Pods

The all-new shift pods have intuitively placed buttons that will feel familiar to users who have ridden the previous generation AXS system. The difference is a more definitive click and less slop. Previous generation controllers are forward compatible with Transmission and the new Pods will operate previous generation AXS drivetrains should users prefer the older style. With the Pod Ultimate on XX and XX SL two sets of buttons are available in a concave or convex shape. The Pods are universally programmable, meaning riders can customize the buttons for different functions. On top of these buttons, the shift pods themselves are symmetrical meaning it is the same unit for left and right for a total of four buttons available. They can be used with RockShox Reverb AXS and Flight Attendant but also allows for eTap-style road shifting setup (i.e. down shift on left side, up shift on right side) or any combination users prefer.

T Type Eagle Cassette

The all-new 12-speed T Type cassette offers much improved shifting performance over previous generations thanks to tighter tolerances between the frame and cassette paired with narrow-wide X Sync cogs throughout. Gear ratios are smoother too with the 52t largest cog now stepping down to 44t and 38t gears. Within the 5th highest gear of the cassette is a red plastic inner ring used for setting B tension and simplifying the setup process. XX SL cassettes use aluminum for the 52t, 44t and 38t rings, XX uses aluminum for the 52t and X0 is nickel-plated steel and rated for e-MTB use.

Cranks

The new line of cranks include XX, XX SL, and X0 models. The integration of an 8-bolt chainring interface is the same as found on SRAM's road lineup. This means previous SRAM chainrings can not be used with the cranks. XX SL comes with an all-new power meter integration said to improve data accuracy. X0 cranks are a ground-up redesign with some very notable design cues made of aluminum and weighing in at less than a Shimano XTR crankset. XX and XX SL feature carbon arms. All chainrings have compatibility for two metal bash guards to be mounted 180° apart.

Brakes

Alongside Transmission are the all-new Stealth brake lever bodies that came in the form of Code Ultimate on our test bike. The brake itself is unchanged from a performance standpoint, with the same calipers from the current generation in a chrome colorway. They utilize carbon lever blades not previously found on Code models. The purpose of the Stealth levers is purely aesthetic and part of SRAM’s pursuit of creating what they feel is the cleanest cockpit possible by eliminating cables and hoses from the line of sight, while mirroring design cues from Transmission components.

Transmission Setup

Starting with the XD driver, SRAM has defined where the edge of the cassette and end cap are. Tying the end cap directly to the derailleur creates the tightest possible tolerance between the cassette and derailleur, eliminating the need for high and low limit adjustments. During setup, the B limit key on the hanger sets B tension location when torquing the derailleur to the frame. The cage lock button can now be flipped to either an A or B position. Derailleurs will come in the A setting while the B setting is used for bikes with a higher level of chain growth. The updated AXS app now has chainstay length data for nearly every UDH-compatible bike on the market to determine the appropriate chain length. Simply enter bike info and chainring size. B Tension lock position and cassette setup cog will be determined by the app. The chain length can also be determined by measuring chainstay length and pairing it with chainring size on SRAM’s provided chain length chart. Setup of the new derailleur is incredibly simple, taking only a matter of minutes after hanging parts, pairing and securing them. SRAM describes the setup process in three steps, cutting the chain to length, hanging parts on the bike, and torquing everything down.

Initial Impressions

Our first few shifts on the new drivetrain had us questioning if we had even changed gears, which is somewhat expected with close ratio 12-speed drivetrains. The addition of a more closely spaced second gear on the new cassette is much appreciated and makes for a very useful climbing gear. Where we really started to scratch our heads was under load, and on the gas where shifts remained seamless despite our best efforts to cause problems. Where we found ourselves with both hands on top of our heads, dying laughing was when SRAM’s Chris Mandell proceeded to lay our test bike on its side, stand on the derailleur, and demonstrate how the new drivetrain continues shifting seamlessly after doing so. We have since stomped on it countless times to impress others. In short, the new mounting interface is legit.

On The Trail

Our introduction to Transmission started in Bellingham, WA, back in January where we spent three days of saddle time spinning up some steep climbs and blasting down even steeper descents between Lookout Mountain and Galbraith. Conditions were wet and sloppy. It was a great introduction to Transmission being able to ride all day long and push the bike to as high a limit as we felt comfortable while familiarizing ourselves with the new interface. From Bellingham we returned to Phoenix to draw some more direct comparisons with what we ride every day, noting the improved shifting under load immediately throughout the technical climbs on South Mountain. From Phoenix we visited Northern California for more steep descents with sustained climbs out. Then we went down to Southern California for higher speed descents with a mix of sustained/technical climbs. Upon our return home we competed in an underground enduro event to see how things held up in a race scenario where shifts are less anticipated.

DH/Technical Performance/Fun Factor

When pointed downhill the most noticeable difference with Transmission over previous generation SRAM AXS drivetrains is how quiet it is. A common complaint among many AXS users is the notably louder chain slap from the derailleur compared to cable actuated models. With Transmission, clutch spring tension is said to be similar to the previous models, but chain retention is where improvements have been made to allow for a quieter ride. We were pleased with how quiet our test bike was and felt confident pushing the bike as hard as we liked without any concern of losing a chain.

Climbing

Shifting under load is where Transmission shines and is most noticeable when changing gears while climbing. Because the system only shifts at the exact cassette ramp locations, individual shifts are seamless with zero break-in cadence or need to plan out shifts. What did require some attention was rapidly shifting from a descent into a climb or vice versa. Coming from previous generation AXS components where each press of the remote results in an instant shift of the derailleur, the new shift pattern of Transmission took some to get used to and required us to keep track of the number of clicks when rapidly shifting. Because the system only allows the derailleur to change gears at the exact shift ramps, the system will queue shifts while waiting for said ramps, which in some instances, creates a delay. In our experience, this often resulted in more shifts queued than anticipated when trying to move across the cassette as quickly as possible, leaving us in a higher or lower gear than anticipated once all shifts were completed. While this was a slight nuance, it is worth noting the system has shifted incredibly smoothly for the duration of our test period, most notably when needing to shift a gear or two mid-climb. Programming to multi-shift does improve the shift speed slightly, too.

Unique Features

The Transmission system as a whole is undeniably unique and just about every part of our XX-level group contained cool features throughout. The derailleur mounting interface is the biggest talking point and being able to stand on it with no repercussions is pretty astounding. The built-in protective features to keep things running smoothly are appreciated. From a rider perspective what we first noticed was the new modular shift pods with a different feeling to the previous generation paddle and the ability to change buttons. Indented lines on every mounting interface of the shift pods are super helpful and will make dialing in cockpit setup between different bikes much easier.

Things That Could Be Improved

With so many improvements made over the last six years, it is hard to imagine any room for more and with the level Transmission is at, it really comes down to splitting hairs. Being the tech nerds we are, we of course found a few things we would change. First and foremost, the multi-shift option is one thing we’ve grown accustomed to. This relates to the methodical approach and sophistication of the system that allows shifts to only be made at the exact shift ramp locations on the cassette. While this is undoubtedly much of the reason shifts are so flawless, it makes timing shifts fairly difficult when so many of us have grown accustomed to shifts happening instantaneously. It is worth noting that pedaling harder does somewhat help initiate shifts more quickly.

Price? Well, that's a moot point with product at this end of the range. We can only hope a GX version drops soon.

Long-Term Durability

We see long-term durability to be a strong point of Transmission and do not foresee any major issues arising for many years to come. Aside from the unparalleled strength of the rear derailleur, the replaceable chainring mounted bash guards should save a bit of chainring damage over a longer period of time and having two mounted means one can be swapped or set aside depending on which foot users ride with forward. The only potential wear and tear item that will need to be replaced after a season or two of use will likely be the shift pod buttons. We opted for the concave-shaped buttons and found the grip pattern softened up slightly over time just like any pair of grips. We see the pattern wearing off over time. That being said, even with the pattern completely worn away the shift pods would still maintain 100% of their function and these items are rather inexpensive to replace.

What's The Bottom Line?

The system maintained incredibly smooth gear shifts throughout the duration of our test period in every situation we tackled. If we were to pick a drivetrain for our next bike build, without a doubt it would be Transmission. Actually being able to afford it might be a different story, but from a longevity standpoint it could even end up saving money in the long run. With features like Magic Pulley, built-in skid plates, and tool-free cage removal, SRAM is looking out for not only their racers but for the average consumer too, which is pretty awesome to see. Being able to replace individual derailleur parts as necessary poses a massive advantage, and the mounting interface offers unparalleled durability that could see derailleurs begin to outlast frames. Our gripes with timing shifts correctly would require a longer adjustment period to develop better muscle memory, but for how smooth the shifting is in every scenario we tested it in, we can only describe the shifting performance as class-leading.

For more information, hit up SRAM.com for more details.

__________________________________________________________________________

About The Reviewer

Jonny started mountain biking in 2003 after a trip to Northstar showed him how much more could be ridden on 26” wheels than on a BMX bike. He began racing downhill in 2004 and raced for 12 years until ultimately deciding having fun on a bike was more important than race results. After working as a mechanic in the industry for a few years and developing a deeper understanding of bikes inside and out, he has an aptitude for pairing his riding ability with the analysis of bikes and breaking down what makes them work well. He spends most of his time between trail rides and skatepark sessions with occasional days on the downhill bike.

View key specs, compare products, and review the latest from SRAM in the Vital MTB Product Guide.