After two years of circuit testing with EWS-E and EDR-E, SRAM’s new electric bike motor is set to be unveiled. Compared to companies like Fazua, Bosch, and Shimano, SRAM entered the e-MTB drive system field relatively late. However, SRAM significantly increased its research and development efforts in the drive system field after acquiring the German mid-drive motor manufacturer Amprio in January last year.
SRAM’s Eagle Powertrain e-MTB drive system is characterized by its simplicity and natural feel, aiming to provide customers with the most natural riding experience possible. ‘The goal of this system is to offer riders a complete, wireless, integrated e-MTB system specifically tailored for high-performance mountain biking. We’ve simplified the riding process, allowing riders to focus on the trail,’ explained Michael Hemme, SRAM’s e-MTB category manager.
The system components include a Bosch motor, 21700 battery, speed sensor mounted on the rotor, top tube-integrated bridge display, two AXS Pod controllers, an AXS Reverb dropper seat post, and a gearbox transmission system. Wiring connects the motor, battery, and display, and the rear derailleur can be connected to the battery.
The motor for the Eagle Powertrain is developed in collaboration with Bosch. The motor hardware is manufactured by Bosch and programmed with SRAM’s proprietary software, resulting in unique motor characteristics. It can generate 90 Nm of torque and peak power of 680 W. The Eagle Powertrain battery comes in two versions: a compact 630W size weighing 3 kg with a 21700 battery and tilted installation, and a full-size 720W version weighing 4.1 kg with a 21700 battery and sliding installation base. Currently, brands like Nukeproof, Propain, GasGas, and Transition have introduced new models designed around the power system.
For a minimalist user experience, SRAM eliminated the front derailleur and wires, providing only two operating modes: Range mode and Rally mode, which can be switched using the button on the left shifter. Range mode offers longer range, while Rally mode provides maximum power output, delivering the strongest riding assistance. The maximum power and assistance level for each mode can be customized in the AXS APP, allowing riders to adjust the motor’s behavior according to their riding preferences.
Many brands equip their vehicles with automatic shifting technology, and the Eagle Powertrain is no exception. It senses the rider’s input and shifts to the corresponding gear, adjustable according to the rider’s preference, reducing the hassle of shifting. Typically, vehicles need pedal movement to shift gears, but the Eagle Powertrain system also features coasting shift, allowing gear changes without pedaling.
The Eagle Powertrain also has a walking mode, activated by holding the shift paddle upwards and walking forward. When the bike enters impassable terrain, the push mode can be activated, automatically stopping when the speed exceeds 6 km/h.
For design flexibility, the Eagle Powertrain battery simplified the interface between the battery and drive unit, offering more power in a smaller footprint, enabling the vehicle to create a more aesthetically pleasing frame profile.
The Eagle Powertrain drive unit is not just a motor. According to SRAM’s description, it also incorporates redesigned power transmission tuning to replicate a more natural pedaling experience. From customizing drive unit power output to easily checking battery life when dismounting, all functions can be viewed and fine-tuned directly through the AXS app on a smartphone. The system integrates with SRAM’s wireless AXS shifting systems, including XX, XO, and GX Eagle transmission systems. It can also be used with SRAM’s mechanical shifting systems without automatic shifting and coasting functionality.