Inside Rocky Mountain’s Unique Powerplay E-Bike Motors

When it comes to making e-bikes, Rocky Mountain is doing things a bit differently than the rest of the industry. I’ve mentioned on at least a couple of occasions about how Specialized has the most proprietary e-bike system around, but I didn’t realize at the time that I was totally lying—Rocky Mountain does.

Specialized works with a company called Brose to supply power units for their e-bikes. Brose offers them a ton of customization and the two brands work closely with one another, but Specialized does not design the motors themselves. In fact, the motor that’s in the third generation Specialized Levo is also in the Rotwild R.X750. Brose allows Specialized to essentially control the rest of the ecosystem, making the same motor behave very differently than it would on any other bike. For instance, Specialized creates the software that runs the motor, they design the remote switch, the display, the app and entire user experience, and they source their own battery, too. It’s more custom and purpose-built than mostly everyone else, but, they still don’t make the motor.

Rocky Mountain does, though. I wasn’t aware of this before, because when Rocky Mountain released its first round of Powerplay bikes four years ago, the media outlet I worked for didn’t cover e-bikes and I wan’t very in tune with what was happening with their development. So, the fact that Dyname, the brand name of the motor on the Powerplay bikes, is a company founded and owned by Rocky Mountain, somehow skipped right by me. You’d think that after hours of rambling on about how much more ahead of everyone else Specialized is, and how nobody beats them on total integration, someone would have corrected me and put me in my place. But that didn’t happen, so I’m doing it to myself.

Being that Rocky Mountain owns its own e-bike motor company, it gets to design the power units however it wants, making them more integrated to the overall mission and purpose of the bikes they’re going onto. Sure, Rocky’s display—even the new ‘Jumbotron’ one that’s integrated into the toptube sort of like the Specialized one—isn’t quite as flashy, but that’s just money talking. Specialized does about $500 million in annual revenue, Rocky does around $40 million. But, what the relatively small Rocky Mountain has accomplished by making its own power unit, might actually put them ahead of where the billion-dollar behemoth, Trek, is right now with its e-bike platform.

Rocky’s control over the motor has allowed its engineers and designers more control over the experience than they’d be able to have by going with the e-bike-in-a-box method that every other manufacture its size does. And, they’ve been able to do some really interesting and unique things that align with the company’s priorities, its size, and the development team’s desired ride characteristics.

Dyname 4.0 Hardware

Essentially, Rocky is aiming to produce e-bikes that are less complex, more field serviceable, and that handle naturally without distracting the rider from the experience of mountain biking. For example, they were turned off by the noise most e-bikes make, so they designed the motor to run at a much lower RPM range and have no planetary gears, resulting in an astonishingly quiet ride. Even in the full-power ‘Ludicrous’ mode, you can barely hear the thing. Instead of a belt or gear-driven transfer gear, Rocky uses a short-pitch chain, which can be quieter, and more durable.

For simplicity, the Powerplay bikes use a regular bottom bracket and a much more standard crank than most other e-bikes do (it’s basically a crank with a DH-length spindle). They do this via a unique system that feeds assistance via a driven pulley, rather than driving the crank spindle itself. If the “bottom bracket” bearings go out on any of the other e-bike systems, which are housed in the motor itself, it might be necessary to send the entire motor in for service. They probably last longer and are more weather sealed than a standard BB, but they’re still a wearing part. You or your local shop can replace the BB bearings on a Powerplay, but likely can’t replace drive shaft bearings on a Bosch motor.

I’m not an engineer, so I’m not sure if this approach of moving the driven part of the system away form the main crank spindle has any inherent advantages or disadvantages when it comes to motor construction, weight, and package size. But, the practicality of essentially bolting the power transfer system (the parts that take the power from the electric motor shaft to the bike’s drivetrain) to the outside of the motor assembly rather than sealing everything into a non-serviceable box seems pretty appealing from a mechanic’s standpoint. And for the record, the Dyname 4.0 motor—which is about 18% smaller than the previous generation—is very close in size to the Brose Drive S Mag motor on the Levo, but the Dyname system makes significantly more power and torque. The Dyname 4.0 delivers 700 watts of peak power and 108Nm of torque, while the Levo makes 565 watts and 90Nm.

The CPU on the Dyname 4.0 is also separated from the motor, meaning that if your mystery electrical box thing is bad, you don’t need to replace the whole motor assembly. Or vice versa. The ability to replace individual pieces of the power unit potentially cuts down on the overall longterm cost to own a Powerplay bike, especially after the warranty is up. And so does the fact that some of the mechanical parts on the power unit can be accessed and replaced at the shop, or even home-shop, level.

Having these parts covered by non-waterproof shrouds does expose them somewhat to the elements, but that’s also by design. I’ve only just received this bike, and I don’t have prior experience or reference data relating to how long the power unit’s components last in the wet, but all of my rides so far have been in terribly sloppy conditions and everything is running smoothly so far. You can tell by the photos that stuff is coming in, but again, that’s on purpose.

The idea is that it’s impossible to keep water out of everything, and sealing electrical connectors is far easier and longer lasting than trying to seal around mechanical parts such as a turning spindle—especially one who’s users expect very little drag from. So rather than trying to keep the whole system dry, Rocky opted to focus on sealing just the critical components, and creating ways for water to escape the rest of power unit housing via drain holes.

You’re starting to see the theme here, right? Don’t over-engineer the thing.

Even the torque sensing system is potentially simpler. While most systems rely on strain gauges for torque sensing, Rocky uses a simple mechanical system that measures chain tension at the tension pulley (the one that’s in-between the upper drive pulley and the chainring on the crank). You put power down and the chain immediately tensions and is recognized by the system. This is apparently computationally simpler with regards to programming, and according to Rocky, improves the systems reaction time. Basically, it’s apparently a more sensitive type of torque sensing system, so it can react to changes faster, creating a smoother, less jerky power delivery. We’ll get into how effective this is soon, in our upcoming comparison test between the new 2022 Altitude Powerplay and the gen 3 Specialized Levo.

Dyname 4.0 Software

Rocky has taken the same “keep it simple, stupid” approach to software. There is no “app for that.” No Bluetooth capability. All the data is displayed and manipulated via the “Jumbotron” display and the handlebar toggle switch.

I think the decision to stay away from messy app development is a rather bold and smart move on Rocky’s part. They’re fully aware that their pockets aren’t as deep bigger companies, so they weighed their options and chose to embrace an on-board control approach. Actually, assuming they made the call for budget reasons is just me projecting. Rocky basically said that the decision was made for simplicity, reliability, and serviceability. App development is tricky and even the best systems today are still glitchy. I can’t even count the times I’ve nearly thrown my phone across the room while trying to connect to an e-bike, my derailleur, or those stupid TireWiz things. Just connecting is glitchy by itself, then, apps themselves are often way worse. Specialized has made a very impressive one, but they’re no-doubt throwing a shitload of money at it—and I have trouble connecting to their bikes sometimes, too.

With pretty much every other e-bike system, you absolutely need to connect the bike to an app in order to make changes to the ride modes, data fields, and/or to do error troubleshooting. Rocky has eliminated that need, and I think that’s pretty awesome. Sure, navigating around the system using a few buttons and a small screen can be a bit tedious, but it sure beats not being able to do anything at all because your phone decided to auto-delete the app to save storage space and you’re out of cell range.

Even the troubleshooting has been made to be more universally possible to do. Many e-bike systems require specific software and a wired connection to the bike in order to perform diagnostics, and not all of this software is available to any consumer, or even every bike shop. The Powerplay bikes can do diagnostics on board and display information that can then be looked up in a manual available to anyone with an internet connection.

There’s a lot more about the Dyname 4.0 system, it’s features and user interface that we’ll get into after I get more time on the bike to futz around with all the options. And, we’ll of course be diving into all the actual bicycle parts of the Altitude Powerplay then, too. We’ll talk geometry, suspension layout, riding impressions, all that. And, we’ll compare this bike here with an S-Works Levo to see how they stack up against each other. For this post, I just wanted to dive into the philosophy and reasoning behind Rocky’s approach to e-bikes, because in many ways they’ve gone rogue—and that’s something I can respect. In the meantime check out the Pinkbike article about the 2022 Rocky Mountain Powerplay models here.

Having the system be totally proprietary, from hardware to software, has many amazing benefits when it comes to freedom of design and implementation, but it’s also not without major challenges, learning curves, and inherent downfalls. It’s pretty easy to see the advantages that universal systems like Shimano or Bosch have over proprietary ones when it comes to long-term service and support. In the bike world, the “P-word” is almost always used with a negative connotation, and for good reason: Bike tech changes fast and companies often to a terrible job supporting the things they no longer make. But if Rocky can follow through by backing up it’s proprietary stuff with support for years to come, their approach of simplifying the e-bike experience might be the company’s best power play.