Bosch adds traction control to its CX and CX-R motors with a free update

Bosch continues to expand the possibilities of its motors for e-MTBs through software updates. The latest version of its eBike Flow application incorporates adjustable traction control that allows you to regulate how the motor delivers power to prevent the rear wheel from slipping. This is particularly interesting for those looking to take full advantage of assistance on technical climbs, wet terrain, or surfaces with low grip.

This is how Bosch's new traction control works

The 1.38 update of Bosch eBike Flow, released on October 12, 2026, introduces several improvements to the brand's Smart System. Although it also includes updates related to transmission response and battery information, the most important change is the ability to configure traction control independently for each assistance mode.

The idea is that excessive torque delivery can cause the rear wheel to lose grip in certain situations, such as steep climbs or loose terrain. To reduce this problem, Bosch uses a system that regulates motor torque with the aim of limiting rear wheel slip.

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The novelty is that now the cyclist can decide how much they want that traction control to intervene, instead of relying solely on the system's automatic management.

From the eBike Flow application, four levels can be selected:

• Off: no traction control intervention.
• Low: reduced intervention to maintain a more direct response.
• Medium: an intermediate level of regulation.
• High: greater intervention to enhance traction on challenging terrain.

These settings can be saved individually for each assistance mode.

For example, a cyclist can set a low intervention level for riding on dry, fast trails while reserving a higher setting for the modes they use on technical climbs, where keeping the rear wheel in effective contact with the ground is crucial.

This allows for adapting the motor response to both the terrain conditions and personal preferences.

The configuration can be found in the Individual Riding Modes > Advanced > Traction Control section of eBike Flow.

It is important to clarify that this is not a system that acts on the brakes. Bosch's traction control directly intervenes in the motor's torque delivery, regulating assistance to reduce the possibility of rear wheel slip.

Which Bosch motors are compatible with traction control?

For now, Bosch limits this function to three specific drive units from its catalog:

• Bosch Performance Line CX-R (BDU386Y).
• Bosch Performance Line CX (BDU384Y).
• Bosch Cargo Line (BDU384Y).

Compatibility depends on the specific version of the drive unit, so it is advisable to check its identification before assuming that an e-MTB will be able to use the new function.

Bosch also allows customization of the Drivetrain Tensioner

The second important novelty affects the Drivetrain Tensioner, a software function that Bosch introduced in 2026 to improve the immediacy of the motor's response.

Its operation consists of keeping the transmission pre-tensioned to reduce the slack that occurs between the start of pedaling and the effective transmission of force. This way, the motor can respond more directly to the cyclist's actions.

This feature is particularly useful in situations where it is necessary to dose power precisely, such as when overcoming steps, tackling very steep ramps, or accelerating out of a tight turn.

Until now, its operation was conditioned by the configuration of the assistance modes. With version 1.38, Bosch allows the Drivetrain Tensioner to be activated or deactivated independently for each customized mode.

This way, the user can opt for a particularly immediate response in certain modes and maintain a different behavior in others.

The function is disabled by default and is available on the same motors compatible with the new traction control adjustment: Performance Line CX-R, Performance Line CX, and Cargo Line, in the previously indicated versions.

More novelties: remaining charging time and improvements in Trick Check

In addition to the changes related to motor behavior, the update introduces two additional improvements.

The first allows you to know how much time is left for the battery to reach 100% charge. When connecting the charger, the display automatically shows an estimate of the remaining time, expressed in hours and minutes.

This function is available on all displays compatible with the Smart System, except for the Intuvia 100.

Users who have the paid Flow+ service and the ConnectModule will also be able to check this information directly from the eBike Flow application.

On the other hand, Bosch has improved Trick Check, its function for recording certain movements and tricks performed on the bike.

It is now possible to incorporate a specific screen on compatible displays and keep the maximum recorded values visible until the next trick is performed.

This possibility is available on the Kiox 300, Kiox 400C, Kiox 500, Purion 200, and Purion 400, although the latter does not allow configuring the screen from the application.

How to install the 1.38 update of Bosch eBike Flow

The new version began to be distributed on October 12, 2026, and can be obtained for free through the eBike Flow application.

Once the latest version of the application is installed, it is also necessary to update the bike's software through the Smart System to access the new features compatible with each motor.

Bosch warns that the availability of the update may vary during the first few days depending on its distribution in app stores.

With this update, Bosch takes another step towards an increasingly personalized management of its electric motors. It is no longer just about choosing how much assistance we want to receive, but also about adjusting how that power is transmitted to the terrain.

In high-performance e-MTBs, where torque delivery can make the difference between overcoming a technical climb or losing traction, having this new adjustment expands the configuration possibilities without needing to modify any component of the bike.

All the details of the update and its compatibilities are available in the official Bosch information on eBike Flow 1.38