Bosch CX Gen 5 Performance Upgrade in the test: More power, more flow – but also more compromises?

E-MTB / Test: A software upgrade gives the current Bosch Performance Line CX Gen 5 motor more power. Up to 100 Nm and 750 watts of power are now possible. Starting in July 2025, owners of e-bikes with the current Performance Line CX Gen 5 can install the upgrade free of charge via the eBike Flow app. We took a close look at the whole process and tested the motor on the test bench and in the field.

The Bosch Performance Line CX motor has been a major player in the e-mountain bike segment for years. When the fifth generation arrived last fall, Bosch expanded its Smart System, but initially, performance remained unchanged: It remained at the familiar 85 Nm of torque and 600 W peak power. While many riders considered this a good mix of power, efficiency, and durability, they still expected at least a small performance boost. Bosch is now doing what we've always expected: Similar to previous generations, it's following up with a software update about a year after the launch.

What's new? This is what the Bosch Performance Upgrade brings

With this update, Bosch is clearly targeting passionate e-mountain bikers – anyone who loves technical trails and wants to push their limits. Of course, it's also likely a reaction to the recently released motors from competitors – especially DJI and Specialized.

More power on demand – individually adjustable

The core of the update: higher limits for torque and power. After the update, users will have the option to increase these beyond the previous limits in the Flow app.

Maximum power: Goes up from the normal 600 W up to 750 W.
Maximum torque: Increases from 85 Nm to up to 100 Nm.
Maximum support: Can be increased to up to 400% of your own pedaling power.

This significant increase in power should be especially helpful on steep, technical climbs. Bosch also says, however, that everyone decides for themselves how much of this extra power they use. Higher values ​​also mean greater strain on the chain, cassette, and gears, and the battery drains faster, reducing range. The app also alerts you when you push the controls in this direction.

Important to know for the upgrade

Availability: From July 2025
Cost: The software update is free
The installation of migRaven.XNUMX/XNUMX can be separated into four different sections, those being: You can do it yourself via “over-the-air” update using the eBike Flow app, no dealer visit necessary
Compatibility: Initially, this is only available for the current Performance Line CX generation (Gen 5 / BDU384Y). Older generations (Gen 4, Gen 2) or the old race engine are excluded. According to Bosch, the new Performance Line CX-R comes with the same performance data.

Important: Manufacturer approval! The bicycle manufacturer must approve the upgrade for the respective e-bike model. Manufacturers also determine how far the power values ​​can actually be increased in the app. Bosch doesn't say directly why this is happening, but one can guess: It's probably to protect components that aren't designed for every torque, such as some hub gears. However, the full potential should be usable on most e-MTBs with derailleur gears.

All Bosch eBike innovations 2o26:

New riding mode: eMTB+ for more dynamics and more power

Along with the performance upgrade, Bosch is introducing the new eMTB+ riding mode. It sits between the familiar eMTB mode and the Race mode (which remains reserved for the Performance Line CX-R).

Support: Up to 400% of the driver's own power, depending on the driver's input.
Extended Boost: The well-known “replenishment” of the motor when you briefly stop pedaling can be dosed just as finely in eMTB+ mode as in eMTB mode, but can last as long as in Race mode.
Dynamic Control: Improved coordination with the sensors should ensure that the power is applied more harmoniously and in a more controllable manner on changing surfaces with different grip levels.

While the eMTB mode is geared more toward touring and range, the eMTB+ mode is all about maximum performance and fun on the trail. Both the eMTB and eMTB+ modes can be further customized with the performance values ​​in the eBike Flow app.
Further innovations in the Bosch eMTB universe

The Bosch Performance Upgrade in the endurance test – test bench and practice

Enough theory, now let's get down to business. How does the Bosch Performance Line CX Gen 5 perform on the test bench and on the trail after the update?

Performance: A significant leap forward

Bosch promises 150 W more maximum power, from 600 W to 750 W. Our measurements on the test bench show: There's a massive increase! We measured a peak power of 685 W. That's not quite the promised 150 W, but it's still a pretty impressive increase in performance. This puts the Bosch Performance Line CX Gen 5, after the upgrade, into the top group of current e-MTB motors. The DJI Avnox is still in a league of its own in terms of performance, and the Sachs RS also delivers a bit more power, but the Bosch now ranks right behind it. Interestingly, in our measurements, it is even around 30 W more powerful than the recently introduced Specialized 3.1 S-Works motor. This power boost is clearly noticeable out there - the upgrade gives the motor noticeably more oomph and transforms it into a different drive system.

Engine characteristics: Sporty and dynamic – but demanding

Bosch remains true to itself: The Performance Line CX is and remains a sporty motor. It doesn't unleash its full power when you pedal leisurely, but rather requires a certain amount of effort from the rider. Our measurements show that you need around 200 W of rider input to access the measured 685 W peak power. This isn't a "blunt" tractor, but rather a progressive drive that thrives on dynamics. The power curve shows that the upgrade pushes the entire characteristic curve upwards. You get more power across the entire power range. The increase is most noticeable at the top end, where the older version reached its limits. We couldn't yet say for sure whether this characteristic can be further tuned for an earlier response via the app settings (assistance factor +/- 5). The software wasn't yet finalized, and the measurement results for customization were therefore inconclusive.

Cadence: The undisputed strength

One area where the Bosch Performance Line CX has always been top-notch is cadence stability – and this remains the case even after the upgrade. The motor delivers its power amazingly consistently across an extremely wide cadence range. It reaches its power plateau at around 60 rpm and maintains this with minimal fluctuations (+/-5-10 W) up to a cadence of 140 rpm. This makes the motor extremely predictable and intuitive to ride. There are no sudden power dips or peaks at high or low cadences, as is the case with other drive units – be it the power drop of the Shimano EP801 beyond 100 rpm or the extra power at high cadence from the Pinion MGU or DJI Avinox. Here, the Bosch continues to set the tone. Only the new Specialized motor (3.1) comes close, but fluctuates a bit more.

The compromise: Thermal management and derating

More power also means more waste heat. Even before the upgrade, the Gen 5 was better cooled than its predecessor, but it wasn't quite as durable as, for example, the Specialized/Brose drivetrain. With the extra power, it was clear: the motor warms up sooner and has to derate its power. Our measurements under continuous load (constant 250 W rider input with good cooling) confirm this: While the old software version could maintain its maximum power for around 12-13 minutes, the motor with the upgrade starts to reduce power after just eight minutes. At this point, we measured a housing temperature of just under 8°C. This indicates that things are getting critical internally, and the electronics are shutting down for protection. Eight minutes of full throttle – that's certainly manageable in practice on long, steep climbs. Other motors like the Pinion MGU, Specialized/Brose, or even the DJI Avinox (despite their fluctuations) last longer in this case.

However, there are two important points that put this into perspective: Bosch controls the power reduction quite cleverly. Instead of a sudden drop, as you see with Specialized or Shimano, the Bosch CX Gen 5 reduces power gently and gradually. This gradual process is barely noticeable while riding. You don't get the feeling of suddenly losing power or that something is broken. The motor then settles at around 80% of its (new) maximum power.

Although the motor loses around 8% of its peak power after 20 minutes, the remaining power is still very high. Comparing the absolute power curve with that of the motor before the upgrade, you can see that even when the more powerful motor is throttled back, it still delivers as much or even slightly more power than the old 85Nm/600W version could deliver. So, even after derating begins, you still have more, or at least the same, power available as before.

consumption and range

Precise consumption measurements on the test bench often reveal little about practical performance. However, one thing is clear: Those who fully utilize the upgrade's additional power and increased torque consume more energy and don't travel as far. The Bosch Performance Line CX has been considered quite efficient so far, and that's unlikely to change. However, when planning your trip, keep in mind: Full power drains the battery faster.

The Bosch Performance CX with Performance Upgrade in practice

In practical testing, the system was operated at maximum power settings. The increase in power is immediately noticeable; the engine delivers significantly more thrust. Contrary to possible expectations, however, the increased power does not negatively affect controllability. Power delivery remains well controlled even at maximum settings.

This results in very dynamic handling, especially in eMTB mode, where the motor responds agilely to rider input. Despite the increased power, there are no noticeable differences in noise levels; the volume remains at the same level as the previous version. Bosch thus achieves a balanced approach between increased performance and precise controllability.

Conclusion

With the performance upgrade for the Performance Line CX Gen 5, Bosch delivers exactly what many sporty e-mountain bikers have been hoping for: noticeably more power and torque. The measured 685 W peak power and the ability to deliver up to 100 Nm of torque elevate the drive unit to the top league of current e-MTB motors. This closes the gap to strong competitors and in some cases even surpasses them. What remains is the superb cadence stability – this is where the Bosch continues to shine.

The ability to adjust the power yourself via the app provides flexibility, but also means you have to deal with the trade-offs: increased wear and tear and reduced range. The biggest technical compromise is that the engine warms up sooner under full load and throttles power (derating). After about 8 minutes, the power is reduced – but very gently and barely noticeable, and the remaining power level is still high.

The free upgrade turns the already excellent Performance Line CX Gen 5 into an even more powerful drive for demanding trails. Those needing maximum continuous power for endless alpine climbs will find motors that are more heat-resistant. However, those seeking a powerful, dynamic motor with excellent cadence stability will find the upgrade significantly boosts riding pleasure and uphill flow. The question remains why Bosch didn't unlock this potential right away, but for those who already own the motor, it's a welcome and impressive development. The addition of the new eMTB+ mode and other system innovations like the Kiox 400C and improved ABS rounds out the package and makes the Bosch Smart System even stronger. All that's missing is a faster charger—but what's not there yet, can still happen.