Bosch has released version 1.38 of its eBike Flow app, a free update for Smart System bikes that hands eMTB riders more control over how the Performance Line CX and CX-R put power to the ground. The headline change: traction control is no longer a fixed function but a setting you can tune or turn off.
What's new in Bosch eBike Flow 1.38
Adjustable traction control
Until now the wheel-slip control built into the eMTB+ mode on CX and CX-R motors could not be adjusted. With 1.38 riders can choose low, medium or high, or switch it off completely. The option sits in the app under custom riding modes, in the advanced settings. It is aimed at loose, slippery climbs where a spinning rear wheel costs both grip and momentum. Bosch's Active Line motors do not get the feature.
Drivetrain Tensioner in every mode
The Drivetrain Tensioner arrived earlier this year for the eMTB+ and Race modes. It uses software to close the freewheel gap between motor and rear wheel, so the pedals bite almost instantly. Version 1.38 makes it available in all riding modes and lets riders enable or disable it per mode; it is now off by default. On full-suspension bikes it may slightly reduce suspension sensitivity, so it is worth testing on your own trails.
Trick Check gets its own ride screen
Trick Check, which logs wheelies, manuals, stoppies and jumps, now has a dedicated full-screen display that stays visible until your next trick. It works on Kiox 300, Kiox 400C, Kiox 500, Purion 200 and Purion 400 displays and cannot be combined with other data fields.
Charging time and 12A charger prep
While the battery charges, Smart System displays (except the Intuvia 100) now estimate the time left to 100%. Seeing the same figure in the app requires the ConnectModule and a paid Flow+ subscription. The update also adds a fast-charging setting that does nothing yet: it prepares bikes for Bosch's 12A Charger, which Bosch has announced for the end of 2026.
The update follows Bosch's free performance upgrade 2.0 from May, which allowed CX and CX-R torque to be raised to up to 120 Nm (within the limit set by each bike brand). Bikes such as the Mondraker Level, Canyon Strive:ON and Merida LITHOS run the CX family. For older update history, see our eMTB firmware updates page.
Bosch eBike Flow 1.38 at a glance
- Traction control
- Low / medium / high / off – Performance Line CX, CX-R (BDU384Y)
- Drivetrain Tensioner
- All riding modes, per-mode on/off – CX, CX-R (BDU384Y)
- Trick Check ride screen
- CX, CX-R, CX Race, SX; Kiox 300/400C/500, Purion 200/400
- Charge-time estimate
- All Smart System displays except Intuvia 100
- Fast-charge setting
- Preparation for the 12A Charger (end of 2026)
- Cost
- Free update via the eBike Flow app
Compatibility for Bosch Smart System components.
Frequently asked questions
Which Bosch motors get adjustable traction control?
The Performance Line CX and CX-R (BDU384Y). Active Line motors do not get traction control.
Can I turn Bosch traction control off?
Yes. Version 1.38 offers low, medium and high levels plus an off setting.
What does the Drivetrain Tensioner do?
It closes the freewheel gap between motor and rear wheel in software, so pedal input turns into drive almost instantly. With 1.38 it can be used in every riding mode.
Does the eBike Flow 1.38 update cost money?
No, the update is free. Only viewing the charging-time estimate in the app needs a ConnectModule and a paid Flow+ subscription.
Does 1.38 enable fast charging?
Not yet. It adds a setting that prepares bikes for Bosch's 12A Charger, which is due at the end of 2026.
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