After years of speculation and the rumour mill running wild, SRAM has finally announced the launch of its e-bike motor, called the Eagle Powertrain.
It has been developed in partnership with Brose and is designed primarily for eMTB use, working in conjunction with their AXS wireless technology and Eagle Transmission. New for the Eagle Powertrain, however, is the addition of automatic shifting.
> Brose Drive³ Peak marks shift to 48V e-bike motors for 2024 and beyond
The Brose partnership is all the more interesting given SRAM's takeover of German brand Amprio earlier this year. Let’s take a look at some of the talking points of this new drive system.
The Brose partnership
SRAM and Brose have put together a punchy, 90Nm motor, offering 680W of peak power. To simplify things, SRAM has chosen to use only two assistance modes: Range mode, which does as it suggests, and works best on easier terrain to manage battery expenditure. Then there’s Rally mode, which is more of a boost mode, ideal for big climbs and tough technical features. Both of these modes can be customised through the AXS app.
There are two sizes of battery to choose from: 630Wh, which offers up to 4.5 hours of use, and 720Wh, which offers up to 5 hours of use. Interestingly, the batteries are removable by use of an Allen key, which could alleviate any fears of removable batteries breaking loose from the holder on turbulent terrain.
The interface between the drive unit and battery has been streamlined, which means we might get the chance to see some really sleek eMTBs taking advantage of the compact area the drive system needs to take up inside the frame.
Auto Shift technology
Perhaps the most exciting aspect of the Eagle Powertrain is the use of Auto Shift tech. This, essentially lets the bike determine gear changes and power output based on terrain, and cadence. It relies on the Powertrain software to select the appropriate gear, but can be overridden by the rider, much like removing cruise control in a car by activating the necessary pedal.
Auto Shift tech also includes Coast shift, which allows the chainring to be moved independently from the cranks. This means that you can change gear when stood still. It also takes note of your speed to choose the most suitable gear. SRAM’s Pod shifters, which may look a little bizarre if you’re unfamiliar, controls Auto Shift, manual shifting, and use of the dropper post.
In addition to Auto Shift technology, the Eagle Powertrain can be synced with Transmission gearing, and some RockShox components, including their Flight Attendant fork and shock, and Reverb AXS seatpost.
Eagle Powetrain AXS Bridge Display
In terms of where all your e-bike data will be displayed, SRAM has gone for a top tube mounted offering called the Eagle Powertrain AXS Bridge Display. This modest display uses Gorilla Glass to protect it from scratches and damage, and displays metrics including ride info and assist mode as well as being where you can switch between Range, Rally and Service mode.
So far, it’s been announced that Propain, Transition, Nukeproof and GasGas eMTBs will use the new drive system. It's also worth noting that it won't be available as an aftermarket upgrade kit.
