Bosch Smart System, eBike System 2, or BES3: What's the Difference?
Both motors are labeled "Performance Line CX," yet they are two distinct technical systems. The battery, charger, display, and motor are not interchangeable.
We explain the differences between Bosch systems and how to identify which one is on a used bike.
Published on: September 10, 2026 | 13-minute read
In a nutshell
- BES3 and the smart system refer to the same thing. "Bosch Smart System 3" does not exist as a separate platform.
- BES2 refers to the eBike System 2, which was launched in 2013; the smart system was introduced in 2021 and became widely available starting with the 2022 model year.
- Gen4 and Gen5 refer to the motor generation, not the system. Performance Line CX is available in both versions.
- The battery, charger, screen, and motor are not interchangeable between the two systems, and conversion is virtually impossible.
- Identify the system using the app, the command, the charging port, and, most importantly, the BDU code.
The short answer: BES3 and the smart system are identical
The Bosch system you see here isn’t always immediately recognizable. Both motors are labeled “Performance Line CX.” The first bike features a Purion display, a PowerTube 625 in the down tube, and a charger with a round plug. The second bike connects to the eBike Flow app, is controlled via an LED Remote, and charges with a BPC3400. Same motor name, different technical ecosystem. And in the ads, the terms BES2, BES3, Gen4, Gen5, and “smart system” are all thrown together haphazardly.
Bosch currently offers two distinct systems: the Bosch eBike System 2 and the smart system. The eBike System 2 was introduced in 2013. The smart system was unveiled in 2021 and has primarily been featured on 2022 model-year e-bikes. Bosch describes this evolution as the transition from a modular approach to a fully connected platform.
BES2 is the common abbreviation for eBike System 2. BES3 is frequently used in retail, repair shops, and technical documentation to refer to the smart system. “Bosch Smart System 3” sounds like a third version of the smart system, but it does not refer to any additional platform. It usually refers to BES3—that is, the smart system.
One more misunderstanding to clear up: motor generation and system generation are not the same thing. In common parlance, “Gen4” or “Gen5” refers to a development stage of the Drive Unit. “BES2” or “BES3,” on the other hand, refers to the entire system: motor, battery, wiring, control unit, display, charger, and software. A Bosch Performance Line CX BDU450 CX belongs to the eBike System 2. The BDU374Y and BDU384Y both belong to the smart system. Therefore, the “Performance Line CX” label alone does not answer the question about the system.
"The Bosch logo, the year, and the engine name don't provide any information about the system architecture. Only the BDU code does."
Bosch eBike System 2: Proven and Widely Used
The eBike System 2 is the oldest platform, but that doesn't mean it's outdated. Bosch has incorporated the Active Line, Active Line Plus, Performance Line, Performance Line CX, Cargo Line, and Performance Line Speed into it. As a result, you'll find the BES2 in virtually every category of e-bike.
Typical on-board computers include the Purion, Intuvia, Kiox, and Nyon. The absence of a number is key here: “Kiox” refers to the BES2 BUI330 display, while the Kiox 300 and Kiox 500 are part of the Smart System. Bosch follows the same pattern with Intuvia and Intuvia 100, as well as with Purion and Purion 200. The brand has carefully crafted its naming scheme. When it comes to navigating the used market, however, the system is less user-friendly.
The Kiox and Nyon BES2 connected displays work with the eBike Connect app and the eBike Connect online portal. A bike equipped with a standard Purion, on the other hand, remains largely offline. You cannot install updates yourself via your smartphone to add new features to the entire system. Diagnostics, configuration, and available software updates are handled through the specialized Bosch network.
BES2 Batteries and Chargers
Depending on the model year and bike, the battery lineup includes the PowerPack 300, 400, and 500, as well as the PowerTube 400, 500, and 625. The DualBattery has a maximum capacity of 1,250 Wh. Charging is done using the BES2 BCS220, BCS230, or BCS250 chargers: 4A Standard Charger, 2A Compact Charger, or 6A Fast Charger. For e-bikes with hardware from the 2018 model year onward, Bosch specifically uses the five-pin charging connector on the bike.
The Smart System: The Fully Connected Bike
With the smart system, the eBike Flow app is no longer just a complement to a specific display, but the digital control center. The motor, battery, control unit, display, and optional components all communicate within the same platform. Riding modes can be adjusted within the limits set by the manufacturer, and updates are transmitted via smartphone and Bluetooth. Some updates must still be performed at a service center.
A display is not required for this connection. A bike can operate with just an LED Remote, or with a System Controller and a Mini Remote. Depending on the model, display options include the Intuvia 100, Intuvia 200, Purion 200, Purion 400, Kiox 300, Kiox 400C, and Kiox 500. The SmartphoneGrip also turns your phone into a display.
The battery lineup has also expanded. The key components of the smart system are the PowerTube 750 and 800, the CompactTube 400, and the PowerMore 250 range extender. The DualBattery now offers up to 1,600 Wh. This does not mean that every one of these batteries fits into any smart system bike. The frame mounting location, mounting length, wiring, and the bike manufacturer’s certification remain key factors.
The Smart System’s 2A and 4A chargers are part numbers BPC3200 and BPC3400/BPC3403 and feature the new angled system connector. In the Bosch documentation, the charging connector on the frame is listed as BCH3901. A five-pin BES2 charger is not compatible with this system. Amperage is not a compatibility standard.
Digital features include the free eBike Lock, navigation, ride data, and customizable riding modes. To use the eBike Alarm, you’ll need the ConnectModule, the Flow app, and Flow+. Battery Lock is also a Flow+ service. “Smart” does not mean, therefore, that every feature is automatically included on the bike or is always free.
Differences in a Direct Comparison
| Features | Bosch eBike System 2 | The Smart System / BES3 |
|---|---|---|
| Launch | 2013 | 2021, especially starting with the 2022 vintage |
| Systems Approach | modular, partially connected | fully connected platform |
| Application | eBike Connect with a compatible display | The eBike Flow app as the system's hub |
| Updates | No OTA feature updates for users | via the Flow app and Bluetooth; some are available at the retailer |
| Typical Displays | Purion, Intuvia, Kiox BUI330, Nyon | LED Remote, System Controller, Intuvia 100/200, Purion 200/400, Kiox 300/400C/500 |
| Batteries | PowerPack up to 500, PowerTube up to 625, DualBattery up to 1,250 Wh | Broader current lineup: PowerMore 250, DualBattery up to 1,600 Wh |
| Chargers | BCS220/230/250, five-pin BES2 connector | BPC3200/3400/3403, Angled System Connector |
| Digital Anti-Theft Device | depends on the old screen and Connect features | eBike Lock; eBike Alarm and Battery Lock, subject to additional terms and conditions |
Refurbished electric bikes with Bosch motors
From the Active Line to the Performance Line CX, across both system lines and with the exact specifications for each bike.
Discover Bosch BikesAre there several generations of the smart system?
There are several stages of development, but Bosch does not market them under the names Smart System 1, 2, and 3. Since its launch, the same platform has been enhanced with new components and features.
The first bundle, for the 2022 model year, included the Performance Line CX BDU374Y, the PowerTube 750, the LED Remote, the Kiox 300, and the eBike Flow app. For the 2024 model year, the Performance Line SX BDU314Y, the Purion 200, the Kiox 500, the PowerMore 250, and the 2A charger were added.
In the fall of 2024, Bosch introduced the Performance Line CX BDU384Y, the PowerTube 600 and 800, the Purion 400, and the ABS Pro for the 2025 model year. Retailers often refer to the BDU384Y as the “CX Gen5.” However, it is part of the smart system and operates within the same Flow ecosystem as the BDU374Y. Additional drive units and software features followed in 2026. This does not upgrade the BES3 to BES4.
This development remains important for you: two smart system bikes may offer different features. Not all older Drive Units receive every new performance option, and components such as ABS, the ConnectModule, or PowerMore can only be added if the bike, the frame, and the manufacturer’s certification allow it. The smart system describes the platform, not necessarily the complete set of features.
How to Identify the Installed Bosch System
The quickest way to test this is through the app. If the bike connects to the eBike Flow app, it has the Smart System. If it uses eBike Connect with a Kiox or a Nyon, it’s part of the eBike System 2. A BES2 bike equipped with a Purion or an Intuvia, however, can work just fine without the app.
Next, take a look at the cockpit. LED Remote, System Controller, Mini Remote, Purion 200, Intuvia 100, or Kiox 300 are clear indicators of the smart system. A Purion without a model number, an Intuvia without a model number, and a Kiox BUI330 all point to the BES2. With a removable display, simply answering “Kiox” isn’t enough. You’ll need the full model designation.
The charging port provides the following information. On newer bikes, the BES2 uses the round, five-pin connector and the BCS220/230/250 chargers. The Smart System uses the BPC3200/3400/3403 and the angled connector. On older Bosch systems, however, don’t rely solely on the connector: adapters are available for the Classic+, and bike manufacturers integrate charging ports in different ways.
The most reliable sources are still the nameplate and the diagnostic report. On the Performance Line CX, the BDU450 CX distinguishes the eBike System 2 from the BDU374Y and BDU384Y smart system motors. This code isn’t always visible at first glance, and you don’t have to remove a motor cover in a parking lot just to buy a bike. Ask the salesperson for the system data or retrieve it from the workshop diagnostic report.
The year of manufacture is only a rough guide. Starting with the 2022 model year, both platforms have been offered simultaneously. An e-bike sold in 2023—or even 2025—may therefore still be a BES2 model. In this case, the model year is not a reliable substitute for the part number. To learn more about the motor systems themselves, see our guide to e-bike motors reviews the main types and their torque.
Can a BES2 be converted to the smart system?
In practice, the answer is no. A system change is neither a firmware update nor a screen replacement. The motor, battery, charger, wiring harness, control unit, sensors, and communication architecture are all part of a specific platform. Added to this are the specific mounting points for the motor and battery within the frame.
Even batteries with the same name aren’t automatically interchangeable. A PowerTube 625 for the BES2 doesn’t become a smart system battery just because the other one also has a capacity of 625 Wh. Always compare the system compatibility, the exact part number, the mounting position, and the bike manufacturer’s approval.
Additional components can still be added within the same system. Bosch cites the Kiox, for example, as a retrofit option for BES2 motors starting with the 2014 model year. On the smart system, an Intuvia 100, a Kiox 300/500, a SmartphoneGrip, or a PowerMore 250 can be added under the right conditions. This is system maintenance, not a migration.
Our take: In a tie, the smart system comes out on top
At Upway, we generally receive electric bikes starting in 2020. So we’re seeing a clear transition between the two worlds: high-performance BES2 bikes from the 2020 and 2021 model years, and the smart system, which is becoming increasingly common starting in 2022.
Our recommendation is clear. If two e-bikes are comparable in price, technical condition, and intended use, we would choose the Smart System. It’s the platform on which Bosch is developing its new motors, batteries, displays, and features. Flow updates, the PowerMore 250, and the latest anti-theft features give you more flexibility over the long term.
That doesn’t mean you should just buy any BES3 bike, though. A well-maintained BES2 bike—with a PowerTube battery in good condition, a clean fault log, the appropriate BCS charger, and a guaranteed supply of parts—is a better buy than a Smart System bike with an aging battery, no BPC charger, or unexplained error messages. When it comes to refurbished bikes, actual condition takes precedence over the most recent platform.
"All things being equal, the smart system comes out on top. With a clear price advantage and proven technology, the BES2, available starting in 2020, remains a reasonable choice."
At Upway, we don’t just check whether the motor is labeled BES2 or BES3. As part of our 50-point quality control process, we evaluate the bike as a complete mechanical and electrical system. To make an informed purchasing decision, you’ll need to know the exact drive unit, the battery and its health status, the correct charger, and a diagnostic report. If you’re still unsure about the motor’s position, our comparison between mid-drive and rear-wheel motors will help you make an informed decision.
Refurbished and Inspected Electric Bikes
Every bike undergoes our 50-point quality inspection and comes with a one-year warranty.
View all e-bikesConclusion: First the system, then the engine and the equipment
The Bosch eBike System 2 and the Smart System are two distinct ecosystems. BES3 is simply another name for the Smart System, and “Smart System 3” is not a third option. Gen4 and Gen5, on the other hand, refer to motor upgrades and should not be confused with the system platform.
When making a purchase, the Bosch logo, the year, and the motor name aren’t enough. Check the app, the control unit, the charger, and—most importantly—the BDU code. Only once you’ve established the system’s specifications can you meaningfully compare batteries, features, parts, and prices. Everything else is a lottery of components—with significantly higher prices. To see how Bosch stacks up against another major brand, check out our comparison between a Bosch motor and a Yamaha motor, or browse our selection of mid-drive e-bikes.