SRAM’s brand-new GX Eagle AXS electric and wireless rear derailleur and shifter takes tech developed specifically for the X01 AXS and XX1 AXS systems and repackages it in a more affordable GX Eagle AXS upgrade kit.
The upgrade kit – which includes a GX Eagle AXS rear derailleur and battery, GX Eagle AXS controller (commonly known as a shift lever) and charger – retails for £554 / $600 / €620.
The complete on-bike system – including derailleur and battery and shifter with a bar clamp – tipped our scales at 545g.
SRAM GX Eagle AXS rear derailleur details
The new GX Eagle AXS derailleur is treated to tech that’s identical to the X01 and XX1 AXS models. This includes a Type-3 Roller Bearing Clutch to help reduce chain slap, SRAM’s Overload Clutch that reduces the chances of damage if the derailleur suffers an impact, increased chain wrap around the cassette thanks to jockey wheel offset, and more ground clearance compared to SRAM’s Eagle mechanical systems.
Like the rest of the AXS lineup, it’s compatible with SRAM’s newest and biggest 10-52t cassettes but will also work with its smaller 10-50t options.
The derailleur has a removable battery – compatible with RockShox’ AXS Reverb and other AXS derailleurs – that powers the inbuilt motor.
SRAM told us that the GX Eagle AXS motor is virtually identical to the higher-spec X01 Eagle AXS and XX1 Eagle AXS versions, hinting at a no-compromises approach to performance and quality.
To protect the motor, and in turn the derailleur and derailleur hanger, from impact damage the GX Eagle AXS derailleur is fitted with SRAM’s Overload Clutch.
This permits the derailleur to ‘move’ out of the way during an impact once the clutch’s pressure threshold is exceeded, disengaging the motor gearbox. The derailleur’s motor then re-engages and rights it back to its original shift position.
SRAM hopes this design will keep the derailleur damage-free and functioning for longer.
A Type-3 Roller Bearing Clutch – as used on all of SRAM’s Eagle derailleurs – also features, but is used to control chain slap rather than as a protective measure.
Elsewhere, GX Eagle AXS has steel-bearing jockey wheels. The lower one continues to use SRAM’s narrow-wide teeth profile – dubbed X-SYNC 1x – to line up with the chain’s profile for improved control.
The GX Eagle AXS derailleur’s cage is stamped steel rather than carbon fibre or aluminium (as found on X01 and XX1), which helps reduce costs but increases weight.
It still features the Cage Lock system where the cage can be locked out in its forward position, removing tension from the chain and making wheel removal easier. It also has b-tension and high and low limit screw adjustments, just like mechanical derailleurs.
Like the other AXS stablemates, the GX version benefits from a more forward design that increases chain wrap around the cassette.
This should improve shifting performance and help increase chain and cassette longevity because more of the chain is in contact with the cassette and jockey wheels in any given gear, compared to a derailleur designed to have less chain wrap.
SRAM GX Eagle AXS controller/shifter lever details
Visually almost identical to X01 and XX1 AXS shifters, the GX Eagle AXS controller comes supplied with the original AXS shifter button rather than the more recently introduced Rocker Paddle. Although the Rocker Paddle upgrade can be bought and installed on a GX AXS controller.
Unsurprisingly, the shifter is Matchmaker compatible (where it can be connected to any compatible brake lever mount) but also comes supplied with a bar clamp.
The three sections of the paddle can be user-programmed (via the AXS app, more on this shortly) to select either up or downshifts.
From the factory, the lower section of the shifter is set to change to a lower gear, while the upper and rear sections are set to change to higher gears. The upper and rear sections activate the same button on the shifter, which is why they perform the same function.
It’s compatible with all current AXS components, including RockShox’ Reverb and RED eTap AXS, because it’s powered by a CR2032 coin cell battery – replacements should be easy to find and cheap to purchase.
How water- and dust-resistant is SRAM’s GX Eagle AXS derailleur and controller/shifter lever?
The GX Eagle AXS rear derailleur has an IP69K waterproof and dust rating.
The number six denotes it is dust-tight, while the 9K means it is sealed against close-range high pressure and high-temperature water spray downs.
An IP69K rating is currently the highest on the IP scale.
SRAM GX Eagle AXS rear derailleur and controller/shifter lever battery life
On a full charge, SRAM claims the GX Eagle AXS derailleur has a battery life of around 20 hours riding time, while the coin cell-powered GX Eagle AXS controller/shifter lever is claimed to have a battery life of approximately two years.
Both the derailleur and shifter have LED battery indicators: green denotes full charge or close to full charge; red indicates 50 per cent charge or near to 50 per cent charge; flashing red means the battery needs charging or replacing.
Battery life can also be monitored in the AXS app.
SRAM GX Eagle AXS rear derailleur and controller/shifter lever customisation and connectivity
Using SRAM’s AXS app, it’s possible to customise the functionality of the controller’s buttons, selecting which one shifts into a higher or lower gear.
You can also select how many gears are changed with a long push of either shift button. It’s possible to program it to shift one, two, three or all the gears both up or down the cassette.
The app also allows you to see which gear the derailleur is currently in and which number of its 31 micro-adjustment positions it is set at.
Firmware updates are performed via the app, too, downloading to the derailleur and shifter using your phone’s WiFi or mobile data connection.
SRAM says the derailleur and shifter connect to one another using their own proprietary encrypted network.
To stop shifter or derailleur hijacking, buttons on the derailleur and shifter, dubbed the AXS button, need to be pushed for the derailleur and shifter to pair with one another or the smartphone app.
Bluetooth and ANT+ connectivity are also inbuilt.
SRAM GX Eagle AXS rear derailleur setup
Integrated into the shifter lever is a third button which, when pushed at the same time as the shifter lever buttons, can be used to trim the derailleur’s position in relation to each cassette sprocket.
The Micro Adjustment has 31 positions, although some of the movements are so small that they’re imperceptible when you’re executing the adjustments.
SRAM has also developed a new b-tension setup tool. Although a full suspension bike will need to be set to sag for it to work correctly, the brand hopes it will make the process easier.
SRAM GX Eagle AXS rear derailleur and controller/shifter lever compatibility
SRAM’s GX Eagle AXS derailleur is compatible with any of SRAM’s current Eagle drivetrain components including SX Eagle, NX Eagle, GX Eagle (mechanical), X01 Eagle mechanical and AXS, and XX1 Eagle mechanical and AXS.
Maximum compatibility was a key factor in its development because it is being sold and marketed as an upgrade kit rather than a full groupset.
It is also compatible with SRAM RED eTAP AXS drop bar shifters, making it entirely feasible to build a GX Eagle AXS equipped 12-speed drop-bar bike as long as other Eagle components are used.
However, SRAM doesn’t recommend pairing an Eagle derailleur with a RED cassette or chain.
SRAM GX Eagle AXS rear derailleur and controller/shifter lever weight
On the scales, the brand-new GX Eagle AXS derailleur with battery and battery cover weighed 465g. The battery alone weighed 25g and the optional battery cover 11g.
The controller/shifter lever weighed 78g including battery and bar clamp.
The GX Eagle AXS derailleur and shifter weigh 545g.
For comparison, a mechanical GX Eagle derailleur weighs 300g, and shift lever including inner cable and bar clamp 134g, totalling 434g, but this is without an outer shift cable.
A full GX Eagle AXS groupset – including cranks, chainring, cassette and chain from the GX Eagle family – weighs 1,881g, while the mechanical equivalent weighs 1,850g but, once again, this is without outer shifter cable.
SRAM GX Eagle AXS rear derailleur and controller/shifter lever prices
A full SRAM GX Eagle AXS upgrade kit, which includes derailleur and battery, shifter with bar clamp, charger, and chain gap tool, costs £554 / $600 / €620.
The GX Eagle AXS derailleur costs £342 / $370 / €384, while the battery cover (sold separately) costs £20 / $20 / €20.
The GX Eagle AXS controller/shifter lever costs £139 / $150 / €155.
When paired with GX Eagle cranks and chainring, cassette and chain a whole GX Eagle AXS groupset will cost £913 / $983 / €1,022.
For comparison, the full mechanical GX Eagle groupset costs £495 / $545 / €555.