SRAM Introduces Powertrain E-MTB Motor System


SRAM Introduces Powertrain E-MTB Motor System

Totally no big deal if you’ve got better stuff to do, but if you wanna read about “Powertrain,” SRAM’s first-ever E-MTB motor, Travis wrote this post. Like, he didn’t ride it or anything, but it’s big news, and we figured you might want to know about it. He talks about stuff like the different modes and how the buttons work and a thing about auto-shifting. No rush, though. The post will just be sitting here. So if on, like, Friday night you’re, like “Oh yeah, that SRAM e-bike thing…” and you haven’t read Pinkbike’s review or whatever, just come on back. But again, not a huge deal if it slips your mind…

This article is not an endorsement of illegal e-MTB use. Illegal use appears to be what drives the e-MTB market here in the Western U.S.–as e-MTBs are illegal on National Forest trails, as well as many State Park trails, a fact that manufacturers and retailers have largely chosen to ignore. But also, this article is not a thesis on how to solve that problem, or any of the many other problems presented by increasing number and power of e-bikes on non-motorized trails. I feel like there will be plenty of that in the comments. All I’m hoping to do here is convey information about one specific important development in the e-MTB market.

At times, I may even do it with some enthusiasm. Though, not a lot of enthusiasm. Powertrain, SRAM’s first e-bike motor, isn’t ushering in the same fundamental changes Transmission did just a few months ago. But I’m not sure what I was expecting. Something like TQ’s Harmonic Pin Ring reduction? Or Fazua’s ultralight, removable system? Or even Pinion’s motorized gearbox? Maybe that wouldn’t be realistic. And there is something interesting going on here. The Transmission drivetrain does open the door for some potentially cool stuff in an e-MTB setting. But there I go, almost getting enthusiastic. Let’s cover the facts.

The motor itself is manufactured by a German company called Brose. If you’re not already familiar, they equip some Rotwild and BH bikes, but they’re best known for making the full-powered motors on Specialized Levo bikes. Or rather, they’re largely not known for it. Most folks (including Specialized themselves) just call the Brose-made Levo motors “Specialized” motors. And that’s actually pretty normal. Specialized, like most bike brands, contracts with third-party manufacturers to produce house-name equipment like saddles and wheels and even frames.

But to varying extents, they’re all made to their respective brand’s specifications. It’s the same thing with the Powertrain motor. As far as we were able to uncover, although the Powertrain motor may not be identical to other Brose motors, we were not told that SRAM’s motor is fundamentally different. SRAM did design the features, software, and interface, which are new and novel, but we’ll get the numbers out of the way first.

Powertrain provides 90 nm of torque (which is the same as the Specialized) and nominal peak power of 680 watts (which is 115 watts more than Specialized [claims]). Its speed is limited to 20 MPH in North America. Powertrain will run on either a 530 or 700 watt-hour battery, depending on what the bike manufacturer chooses to spec. Plus, there’s an optional 250 watt-hour bottle-mount external battery.

The display is integrated into the top tube, but only has two buttons: a power button, and a mode button to toggle between its two modes, “Range” and “Rally.” Instead of offering four assist profiles, SRAM is offering essentially what is just an eco and a sport mode. And in each of those two modes, you have just two power adjustments, done through the AXS app. You can limit the max wattage output, which is simple enough. But you can also micro-adjust the assist from “Dynamic,” (being tied closely to your personal power output), to “Supportive,” (going full-tilt as soon as you push on the pedals) and anywhere in between.

The simplicity in available modes makes Powertrain a bit of an outlier. Bosch offers bike manufacturers ten modes to choose from. Shimano offers the end-user control over things like how much or little assist is given immediately after you start pedaling. Specialized offers a mode with on-the-fly adjustment of power assist, acting almost like a second shifter. Apparently, that’s not the experience SRAM was trying to offer.

That may be why they’re putting so much emphasis on the Autoshift mode. It probably sounds like a bad idea to most of us. At first, it sure sounded like a bad idea to me. But I’ve heard from riders I trust who have used Shimano e-MTBs’ new auto-shift setting, and they’ve been surprised how much they like it. But it should work even better on a Powertrain bike. You can reliably shift under load when running a Transmission drivetrain, which is a mandatory spec on Powertrain bikes.

This is not the sort of thing that would get me to buy an e-MTB, but it’s kinda fun to imagine what it’d be like to approach a climb, where the motor naturally assists based on my torque, and the derailleur naturally shifts based on my cadence. Not gonna lie, it gets me curious about what that would feel like.


Another thing unique to SRAM’s system is its controllers. The move to a button-style “shifter” introduced alongside Transmission allowed them to go from the on-bar, grip-side buttons used by most e-bikes to a more familiar below-bar setup. Theory being, it’d be more intuitive for people to make on-the-fly tweaks to their settings. For instance, a long press of the top button on the right controller takes you in and out of Autoshift mode.

Once you’re in it, the right controller essentially adjusts that mode. An “easier” setting would execute its downshifts under lower torque, whereas a “harder” setting would keep you in higher gears for longer. As for the left trigger, the top button switches between the motor’s two assist modes, the bottom button would actuate the dropper. On that note, an AXS dropper isn’t technically mandatory like the Transmission drivetrain.  You can use a cable-actuated dropper, but you’ll be forced to put its lever somewhere else.

That dropper post sparked some nagging doubt about this new system. First, SRAM wouldn’t comment on whether or when they’re going to make a 200mm AXS dropper. So, tall folks may be stuck with a 170 for a while. But my other seatpost nitpick relates to price point. A lot of otherwise full-AXS bikes spec a traditional dropper post because an AXS dropper would bump the complete cost clear into the next bracket.

But as far as we’ve learned, all Powertrain bikes will spec AXS droppers and Transmission AXS drivetrains. That means that SRAM, a huge potentially influential player in the e-MTB market, has decided they only want serve the ultra-high end. And yes, I know e-MTBs are already exclusively high-end. Canyon, YT, and Fezzari, arguably the highest-value bikes out there, don’t even bother making an affordability-focused aluminum full-suspension e-bike.

They’re carbon-only, and start at $5,000. But at launch, the only Powertrain bikes on the market will be starting at twice that price. Without the option to drop electronic shifting or electronic dropper posts, it’s unlikely Powertrain-equipped bikes will ever go (meaningfully) lower than five-figures.

I doubt most of our domestic readers would consider it a tragedy that the SRAM motor isn’t priced to reach a huge audience. Some might say, the fewer e-bikes on the trail, the further we can kick the inevitable reckoning down the road. Again, I’m not here to comment on that. I’d love to end this piece in a way that’d reveal my personal position on the issue.

But I’ll save that for a Dust-Up…