Summary
The Bosch Performance Line CX is a mid-drive e-bike motor developed specifically for performance mountain biking. Introduced in 2015, it has evolved through several hardware generations and is now deeply integrated with Bosch’s Smart System.
The current Performance Line CX BDU384Y ships with 85 Nm of torque, 600 W maximum power and 340% support, but compatible bikes can use Bosch’s 2026 Performance Upgrade 2.0 to reach as much as 120 Nm, 750 W and 600% support under defined conditions.
Key Facts
- Introduced: 2015
- Category: E-Bike System
- Common name: Bosch CX
- Current model: BDU384Y
- Motor type: Mid-drive
- Rated continuous power: 250 W
- Standard current torque: 85 Nm
- Maximum configurable torque: Up to 120 Nm
- Standard maximum power: 600 W
- Maximum upgraded power: Up to 750 W
- Weight: Approx. 2.8 kg
- System: Bosch Smart System
- Primary use: Trail, all-mountain and enduro e-MTBs
- Configuration: eBike Flow app
- Assisted speed: Typically 20 mph US / 25 km/h EU
- Official website: https://www.bosch-ebike.com
Overview
Bosch introduced the Performance Line CX in 2015 as a drive unit specifically aimed at increasingly capable electric mountain bikes. Bosch Performance Line CX
Since then, the CX name has covered several substantially different motors. This is important because an early CX, a 2020-era CX, a Smart System BDU374Y and the current BDU384Y are not the same drive unit despite sharing the Performance Line CX name.
Major stages include:
| Era | Major Change |
|---|---|
| 2015 | Original Performance Line CX introduced |
| 2020 | Major reduction in motor size and weight |
| Smart System era | Flow-app connectivity and expanded digital integration |
| 2024 / MY2025 | Current BDU384Y generation introduced |
| 2025 | First software performance upgrade |
| 2026 | Performance Upgrade 2.0 increases available torque and support further |
The current BDU384Y is lighter, quieter and more compact than earlier CX generations while offering substantially more software-defined performance.
How It Works
Performance Line CX is mounted around the bottom bracket and combines motor torque with the rider’s input at the crank. Power then passes through the bicycle’s chain, cassette and rear wheel.
The controller continuously evaluates inputs including:
- Rider torque
- Pedaling cadence
- Wheel speed
- Selected riding mode
- Motor and system conditions
The resulting assistance is controlled electronically rather than following one fixed torque curve.
This is particularly important off-road, where simply applying maximum motor torque can cause the rear wheel to lose traction.
Dynamic Riding Modes
Bosch provides multiple riding modes depending on the bike, firmware and manufacturer configuration.
These can include:
- Eco
- Tour+
- eMTB
- eMTB+
- Turbo
- Auto
Additional modes are available on certain Bosch drive units such as the CX-R.
eMTB Mode
eMTB mode automatically varies motor assistance according to rider input. Light pedal pressure produces relatively low assistance, while stronger input produces substantially more support.
The rider can therefore move between moderate assistance and high output without manually changing modes constantly.
Extended Boost
Extended Boost is designed for short technical obstacles. Motor assistance can continue briefly after the rider’s pedal impulse, helping the bike clear steps, roots and other situations where continuing a full pedal revolution may not be practical.
Current Smart System versions allow greater control over this behavior through the Flow app.
Performance Upgrade 2.0
This is the most important change to the modern CX specification.
The current BDU384Y still leaves the factory at:
- 85 Nm torque
- 600 W maximum power
- 340% maximum support
However, Bosch’s Performance Upgrade 2.0, released in May 2026, allows compatible systems to reach:
- Up to 120 Nm
- Up to 750 W
- Up to 600% support
The 600% assistance figure applies only at speeds up to 15 km/h (9.3 mph) and in compatible riding modes. Full output also depends on battery and system configuration. Bosch Performance Upgrade 2.0
Importantly, the bicycle manufacturer can restrict the maximum values available through the Flow app.
This means two bikes with the same BDU384Y motor may not offer identical maximum settings.
Bosch also explicitly notes the trade-off: increasing motor output can increase component wear and reduce battery range.
Why the Standard Setting Is Lower
The fact that Bosch ships the CX at 85 Nm despite allowing substantially more output is significant.
The standard setting represents a compromise between:
- Performance
- Range
- Traction
- Heat generation
- Drivetrain durability
- Battery demand
The 120 Nm setting should therefore be understood as an available performance configuration, not evidence that every rider should immediately maximize every slider.
For many trail conditions, controlled torque is more useful than maximum torque.
Smart System Integration
Current CX motors form part of Bosch’s Smart System rather than operating as standalone components.
The Smart System can incorporate:
- Drive unit
- PowerTube or PowerPack battery
- System Controller
- LED Remote or Mini Remote
- Kiox or Purion displays
- eBike Flow app
- ConnectModule
- eShift
- Bosch eBike ABS
The Flow app provides functions including:
- Firmware updates
- Ride-mode configuration
- Motor-performance adjustment
- Navigation and ride recording
- System information
- Security functions
Some connected or security features require additional hardware or services.
Battery Compatibility
Battery compatibility should not be judged simply by capacity.
Current CX-equipped bikes can use several Bosch Smart System battery configurations, including PowerTube batteries such as 600, 750 and 800 Wh versions. DualBattery configurations are also available in appropriate applications.
However, the battery, wiring and drive unit must belong to compatible Bosch system generations.
Maximum output can also depend on the installed battery. Bosch notes that sustained 750 W operation is available only with specified battery combinations and is affected by factors including state of charge, temperature and cooling.
Performance Line CX Generations
One of the biggest sources of confusion is the continued use of the CX name.
Earlier Bosch eBike System 2 CX
Older Performance Line CX systems use Bosch’s previous electrical architecture and components.
BDU374Y Smart System CX
This brought the CX into the Smart System ecosystem with Flow-app connectivity and modern controls.
BDU384Y
The current generation further reduced noise and weight and improved control while greatly expanding software-adjustable performance.
These drive units should not be identified solely as “Bosch CX” when servicing or ordering components.
Notable Applications
Performance Line CX is used across a very large number of e-MTB platforms.
Orbea Wild / Wild TR
Current Wild models use the BDU384Y-generation Performance Line CX with Bosch PowerTube batteries. Orbea Wild TR
CUBE Stereo Hybrid ONE44
Current Stereo Hybrid ONE44 models combine the CX with an 800 Wh PowerTube, with compatible configurations advertising the upgraded 120 Nm maximum. CUBE Stereo Hybrid ONE44
Trek Powerfly+
Current Powerfly+ models also use the Performance Line CX with available output up to 120 Nm. Trek Powerfly+
Other CX-equipped platforms are available from brands including Mondraker, Haibike, Bulls, Cube, Orbea, Trek, Pivot, Santa Cruz, Yeti, Transition and many others.
Mechanic’s Perspective
The first rule with a Bosch CX bike is: identify the actual drive unit, not just the CX logo.
BDU384Y, BDU374Y and older eBike System 2 CX motors belong to different generations with different component and software compatibility.
For a no-assist or intermittent-assist complaint, useful first checks include:
- Battery condition and connection
- Wheel-speed sensor and magnet
- Wiring and connectors
- Controls and displays
- Firmware versions
- Stored diagnostic errors
On current Smart System bikes, motor behavior should also be checked in the Flow app. With Performance Upgrade 2.0, two mechanically identical bikes can have dramatically different torque and support settings.
That becomes particularly relevant when diagnosing accelerated chain, cassette or chainring wear. A BDU384Y configured near 120 Nm places very different loads on the drivetrain than the same motor operating near its original 85 Nm setting.
Good shifting technique, appropriate cadence and more frequent chain-wear checks become increasingly important as motor output rises.
Bosch dealer diagnostics should be used for electronic troubleshooting and firmware management. Internal drive-unit repair is generally handled through Bosch’s established service or remanufacturing channels rather than routine shop disassembly.
Common Misconceptions
“The Bosch CX has 120 Nm.”
Potentially. The current BDU384Y ships at 85 Nm but compatible systems can be configured up to 120 Nm.
“All Bosch CX motors are basically the same.”
No. The CX name has existed since 2015 across several substantially different hardware and electronic generations.
“600% assistance is available all the time.”
No. Bosch restricts the maximum support level to specific modes and low-speed conditions.
“Every BDU384Y can simply be set to maximum output.”
No. OEM restrictions, battery compatibility and system configuration determine the available limits.
“More torque is always better.”
Not necessarily. Higher output increases battery consumption and drivetrain loading and can make traction harder to manage.
“Smart System parts work with older Bosch systems.”
Not automatically. Bosch eBike System 2 and Smart System components belong to different architectures and compatibility must be checked explicitly.
Related Terms
- Bosch
- Bosch Smart System
- Performance Line CX-R
- Performance Line SX
- eMTB Mode
- Extended Boost
- eBike Flow App
- Mid-Drive Motor
- Torque Sensor
- Pedal Assist System