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Bosch Nyon: wheel circumference (dealer-set)

Bosch Nyon

The Nyon shows the wheel circumference under My eBike but the base value is dealer-only in DiagnosticTool, because it defines the 25 km/h cut-off. A small correction may be allowed on the BUI350.

Step by step

  1. Settings (gear) > 'My eBike' > 'Wheel circumference'. The stored value in mm is shown.
  2. BUI350: on firmware that allows it you can correct the value by a few percent; confirm. This only refines displayed speed and distance.
  3. BUI275: the value is read-only.
  4. For a real change (other wheel or tyre), measure the circumference (mark the tyre, roll one full turn with rider weight, measure in mm) and have a Bosch dealer set it in DiagnosticTool.
  5. Back with the back arrow.
Tip: GPS speed on the Nyon's navigation screen is a quick sanity check: if wheel speed and GPS speed differ by more than 2–3% on a straight road, the circumference is off.

Can't find it?

If the value refuses to change, it is dealer-locked, which is normal. Jumping or zero speed is the speed sensor and magnet, not the circumference.

Frequently asked

Why is wheel size locked on Bosch?

It sets the real speed of the 25 km/h assistance cut-off; only dealers may change it.

Can the ±% correction change the cut-off?

No, the cut-off is derived from the dealer value in the drive unit.

Does the Nyon use GPS for speed?

No, wheel speed from the sensor; GPS is for navigation only.

Manuals and video

Other Bosch Nyon guides

Bosch Nyon: change the display language (BUI350 and BUI275)Bosch Nyon: switch from mph to km/h (or km/h to mph)Bosch Nyon: set the time (usually automatic)Bosch Nyon: reset the trip distance and ride statisticsBosch Nyon: change assist modes and customise them (BUI350)Bosch Nyon: activate and use eBike LockBosch Nyon: set the display brightness and night modeBosch Nyon: pair with eBike Flow (BUI350) or eBike Connect (BUI275)Bosch Nyon: update the firmware (Flow, Wi-Fi or dealer)Bosch Nyon: enable and use walk assistBosch Nyon: turn the lights on and off, automatic and always-on lights
Still stuck? Take a photo of the display and show it to a local e-bike workshop. Bring the bike's system name (e.g. Bosch Performance Line CX) and the exact code; that saves diagnostic time and money.