Bosch Smart System: wheel circumference (dealer-set, small correction in app)
The base wheel circumference is set by the manufacturer or dealer in DiagnosticTool; eBike Flow and the Kiox 300 allow only a small cosmetic correction. It never moves the 25 km/h cut-off.
Step by step
- To see the stored value: Kiox 300/500 > Settings > 'My eBike' > 'Wheel circumference'; or eBike Flow > Settings > your eBike > components / wheel circumference.
- On firmware that allows it, adjust within the small permitted range (a few percent) with + / − or the slider and confirm. This corrects displayed speed for tyre pressure and wear only.
- For a real change (other wheel or tyre size), measure the circumference (mark tyre, one full roll with rider weight, distance in mm) and give it to a Bosch dealer.
- The dealer sets the base value in DiagnosticTool in a few minutes; it is often done during a service.
- Do not expect the correction to change when assistance stops: that is derived from the dealer value in the drive unit.
Can't find it?
If the item is read-only, your firmware or manufacturer does not allow user correction; dealer only. Speed jumping or dropping to zero is a sensor/magnet problem (on the Smart System often the rim magnet or the sensor cable), not the circumference.
Frequently asked
Why can't I set the wheel size myself?
It defines the real speed at which the 25 km/h cut-off happens. Bosch keeps that dealer-only in DiagnosticTool.
What does the app correction do?
Fine-tunes displayed speed and distance within a few percent; assistance cut-off unchanged.
New tyres, do I need the dealer?
Only if the tyre size changed noticeably; same size, same setting.
Manuals and video
- Bosch eBike Help Center: official error-code index
- Bosch eBike downloads: quick start guides and battery guide
- Bosch eBike dealer search (DiagnosticTool readout)
Videos found on YouTube and checked automatically; they are other people's work, not ours.