Firmware update for Sram's AXS Transmission: Faster shifting thanks to new software?

With firmware version 2.53.8, Sram presents an update for the Eagle AXS Transmission derailleur, which is intended to noticeably improve shifting speed during multiple gear changes. At the heart of the update is an optimisation of the so-called cassette mapping - a technology that enables precise coordination between the X-Sync technology of the cassette and the electronically controlled movements of the rear derailleur.

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The Eagle Transmission Cassette Mapping combines the special gearing of the cassette with very defined shifting lanes with precisely timed movement sequences of the rear derailleur, which are controlled via the AXS firmware. This specific shifting sequence with its defined timings enables the chain to move across the cassette while remaining fully engaged throughout. According to Sram, this allows bikers to shift gears at any time and at any point, even under load. With the new firmware 2.53.8, Sram now reduces the time between successive shifting operations with three or more gears and adapts the movement sequences better to typical rotation speeds of the cassette.

Our test actually shows that shifting under load is extremely smooth and easy with the transmission, which is an immense advantage for e-bikes in particular. However, the shifting speed is higher with Shimano gears. If you pedal and ride very slowly, for example on a steep climb, you may have to think for a second with a transmission until the chain has reached the "shifting window" on the cassette.

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Years of testing as the basis for optimisation

According to Sram, the development of the update is based on years of additional tests that were carried out after the market launch of the Eagle Transmission System. This has made it possible to increase the shifting speed without compromising the chain guide standards required for optimum shifting under load. The firmware update specifically includes a timing update for the cassette mapping multishift intervals. This means that the rear derailleur moves faster between the gear positions during successive shifting operations of three or more gears. Whether this actually leads to a noticeably faster shifting performance, however, depends heavily on the position of the chain on the cassette, as Sram emphasises. Shifting between the sprockets is made possible by the rotational speed of the cassette in combination with the movement of the rear derailleur between the gear positions.

Complex interaction between rear derailleur and cassette

Shifting with the Eagle Transmission involves two independent movements. Firstly, the rear derailleur gives the impulse to change gear. Then the specially provided shifting lanes or climbing aids in the sprockets "transfer" the chain to the next sprocket. Firmware 2.53.8 was developed to better adapt to the usual rotation speeds of the cassette while riding. After years of further testing and riding data, the company is now convinced that the time between successive shifting operations can be reduced while maintaining the industry-leading shifting performance under load and the durability of Eagle Transmission cassettes and chains.

Faster shifting also suitable for e-bikes?

Interestingly, according to Sram, the timing update should be noticeable both with and without the Multishift function activated (shifting many gears by holding down the button). On pedal-powered bikes, activating Multishift enables the fastest possible shift input. However, Multishift must not be used on e-MTBs and pedelecs with electric assistance in order to maintain the warranty - an important note for e-bike owners. Nevertheless, advantages should be noticeable, namely when manually shifting more than three gears at once.

Availability and compatibility of the update

The firmware update 2.53.8 is now available to existing Eagle Transmission users via the Sram AXS app. It is also supplied with the limited Eagle Transmission 1987 Groupset Edition and is pre-installed on all new Eagle Transmission derailleurs currently leaving the factory. According to the manufacturer, updating the firmware via the SRAM AXS app is easy. Users can find detailed instructions in the corresponding support documentation on the SRAM website.

The facts about Eagle AXS Transmission Firmware 2.53.8

• Main function: Optimisation of the cassette mapping multishift intervals
• Compatibility: All Eagle Transmission rear derailleurs
• Availability: Via SRAM AXS App, on limited Eagle Transmission 1987 Groupset Edition, on all new rear derailleurs ex works
• Area of application: Faster multiple gear changes (three or more gears)
• Special feature: Can be used with and without activated multishift function
• Restriction: Multishift function not for e-MTBs and pedelecs with electric assistance (warranty)