SRAM EAGLE POWERTRAIN
SRAM’S entry into the e-bike arena marries motor and transmission for a match made in heaven
It’s no secret that SRAM’S had a motor cooking for quite some time. Last year, Nukeproof racer Elliot Heap was spotted racing with a prototype at the EWS-E for one thing. Then SRAM acquired Amprio, a German motor brand. So while the product itself is no surprise, it’s what’s lurking beneath the covers that’s intriguing, and potentially divisive.
In recent years, SRAM has increasingly funnelled its components down the path of system integration. By optimising individual parts to work together in a structured way, variables can be eliminated and performance can be enhanced. Although mountain bikers notoriously hate being beholden to a specific brand, or system, when it comes time to replace worn or broken parts.
But that’s a debate for a different day. The point is, Eagle Powertrain takes this strategy to new levels, which, depending on your viewpoint, is either extremely exciting or hugely frustrating.
SRAM’S new e-bike Powertrain is designed to work exclusively with its new T-type AXS transmission. To enjoy Eagle Powertrain’s advantages, you have to go – if you’ll excuse the phrase – balls deep. Those advantages are two-fold: full wireless control of power modes, gear changes, and dropper post; and the potential to let the system shift for you, using Auto Shift and Coast Shift. Of course that’s not the full story, but these are the headlines that set SRAM’S offering apart from rivals Shimano, Bosch, and Specialized. With that in mind, let’s dive straight into the details.
MOTOR AND BATTERY
If you’ve owned or ridden a Turbo Levo then the SRAM motor will feel pretty familiar. It’s the same, physically chunky, 2.9kg, Brose motor used by Specialized, albeit running SRAM’S firmware and some slightly tweaked internals, one of which is a drive belt that has been further reinforced to prevent stretching and slipping. Four and six-bolt mounting options are available, and brands can make their own custom motor covers, but frame integration is a bit of a mixed bag. Nukeproof’s clocked design looks sleek, but on the Transition Repeater it’s definitely a less elegant solution.
Top line stats on the motor are an impressive claimed peak power of 680w – far in excess of the 565w delivered in the Turbo Levo. And much higher than Shimano’s EP801 and Bosch’s Performance CX. At 90Nm, claimed torque also exceeds its two main rivals, even if it’s by just 5Nm.
To power the motor, brands can choose from two different capacity batteries. A smaller, lighter (3.1kg) 630Wh, or a larger 720Wh option (4.1kg). There’s also an optional 250Wh range extender with Fidlock mount.
SRAM steers clear of providing any estimates on range, but to give an idea, here’s what I achieved over two rides at Golfie in dry conditions on the Propain Ekano 2 29er shod with Maxxgrip Double Down tyres and fitted with the 630Wh battery. The first day was 1,451m of climbing and descending using both power modes. Day 2 was 1,567m in a mix of modes, completely emptying the tank in the process. On both days we rode some very steep climbs, which obviously puts more load on the motor and battery. In my experience, considering the gradients involved and the heavyduty, slow-rolling, tyres fitted, that’s a very good result.
DISPLAY
In another nod to the Turbo Levo, SRAM’S AXS Bridge display unit is integrated into the top tube and uses a small colour screen, protected by Gorilla Glass, to keep you informed of battery levels and current power mode. It has two buttons, one to turn the bike on, and the other to switch power modes. Compared to Specialized’s unit, the depth of information it can display is more basic. The font is quite small, so it’s not the easiest to read at a glance, and I’d prefer if the layout was customisable like the Turbo Levo display, maybe with the addition of a clock function.