SRAM’s new Eagle Powertrain electric bike motor has been officially unveiled, ushering forward a new era of ultra-smart e-bike motors that know what you want to do before you even know it.
The SRAM Eagle Powertrain has two key features that help set it apart from the competition. Relying on the company’s drivetrain experience, the mid-drive motor has been designed with predictive shifting known as Auto Shift.
It’s not the first automatic transmission for e-bikes, but it is one of the few models on the market that incorporates it directly into the e-bike drive system itself.
Baked into the SRAM Eagle Powertrain’s software, Auto Shift allows the drivetrain to select the right gear for the rider’s current pedaling cadence and lets the system change cogs automatically even under different power scenarios.
To take that concept one step further, SRAM also rolled out Coast Shift, a system that allows the drivetrain to shift gears even when the rider isn’t pedaling. That’s a feat that normally isn’t possible using a chain drive system, since the chain needs to be moving to hop from one cog to another. But with Coast Shift, the motor is smart enough to engage itself enough to turn the chain even when the rider isn’t pedaling. It sounds simple, but it’s a revolution in shifting gears with a chain drive.
The functionality sounds a bit like blipping the throttle on mid-drive motors that have throttle options, giving just a momentary amount of power sans pedaling to get the chain moving and allow the derailleur to do its job. But instead of having to think about it, the rider can focus all of his or her energy on the path ahead while allowing the drivetrain to control the Auto Shift and Coast Shift features on its own.
If you’re wondering how a company better known for its shifters managed to develop an entire electric bicycle motor system, the answer is that it didn’t.
Instead of reinventing the wheel, SRAM teamed up with Brose, an established electric bicycle drive system manufacturer. That means SRAM was able to leverage Brose’s German-made motors and focus on creating their own software to unlock those intelligent features in the motor.
Partnering with Brose also helped SRAM reach industry-leading performance on the hardware side, besting motors from big names like Bosch and Shimano. The SRAM Eagle Powertrain motor offers a peak torque of 90 Nm and up to 680 watts of peak power (even if the pesky continuous power rating is a compliance 250 watt figure).
The motor can work with Brose’s 630Wh and 720Wh e-bike batteries as well as the company’s 250Wh auxiliary battery that functions as a range extender.
SRAM’s other AXS components that use the company’s wireless protocol can be used seamlessly with the Eagle Powertrain drive system, controlled by SRAM’s Pod Controllers, resulting in a more elegant-looking wireless solution.
The new drivetrain is expected to roll out on SRAM-powered electric bikes from several manufacturers, though will likely be limited to high-end e-bikes.