Introduction
The TMM sensor can be calibrated at two points in the Onni:
- Omni > Sensor - Calibration
- Omni > Service menu - Sensors - Reset Offset
The following values are displayed in the service menu:

The aim of the calibration is to achieve a differential voltage of 0 V between 'voltage' and 'adjust'. To achieve this, the calibration sets the offset to the TMM voltage 'voltage'. After the calibration or reset offset (service menu), both values show the same voltage and the control electronics in the Omni act neutrally, i.e. no support is generated. Motto: Where there is no input, there is no output.
When pedaling, the TMM sensor immediately generates an increased voltage, proportional to the force exerted on the chain/belt. The differential voltage now generated between 'offset' and 'voltage' is evaluated by the Omni and the motor is instructed via the controller to provide more or less support.
Calibration - in general
- The wheel should not be moved when starting up the OMNI.
- Sitting up (without touching the pedal) during calibration was called up in the calibration process for the ST1x, among others. The instruction can no longer be found in the newer models. Sitting on the pedal affects the 'voltage' value ('TMM' on the old ST1x) by approx. 20-30 mV and can slightly shift the assistance control in the direction of 'self-propulsion'.
- The 'moped trick' (see below), which has been bandied about in the forums, in which the support curve is to be shifted in the direction of 'self-propulsion' by means of a negative offset ('offset' < 'voltage'), can improve the agility of the bike. However, you should not overdo it. Values above 30 mV result in a scooter effect and may be dangerous and cost range.
- Calibration and 'Reset Offset' in the service menu (under Sensors) have the same effect.
- The temperature drift of the sensor and the temperature at which it is calibrated have an influence on the support.
> See Chapter 'Details and technical data' - When diagnosing faults, the TMM sensor is often targeted as the 'culprit' and replaced straight away. Due to its robust design, the sensor is usually not the problem.
> See Chapter 'Problems with support and possible solutions' - Increasing the tightening torque of the rear axle reduces the output voltage of the sensor (in the service menu = 'voltage') and vice versa.
Voltage of the 'voltage' value
The quiescent voltage of the sensor is different for the various current sensor models. It must lie within a voltage range defined by the model (see table under point 3.4). For example, one model runs optimally with 0.68 V, another only with 1.2 V sensor quiescent voltage. There are also small deviations within the same model. Not every Stromer runs the same. The values depend on the tightening torque of the rear wheel thru axle, the fastening screws of the sensor plate and the adjustment of the actual sensor on the sensor plate. In the new sensor models (P211/P218), the sensor is potted. The older models still had two vertically arranged fastening screws and a grub screw for horizontal basic adjustment.
The following applies: more tightening torque on the stub axle = lower tension 'adjust' and vice versa. The torque/tightening torque specifications from Stromer should be adhered to.
Update
With the Fimware SUI 4.5.0.3 dated March 5, 2025 a bug was fixed which in practice made calibration necessary again and again. Stromer writes in the release notes:
A bug that caused the vehicle to no longer provide support if the TMM sensor value was slightly too low has been fixed.
Moped trick...
V1: Push/pull the rear wheel slightly to the right at the top, stand on the left side of the wheel, place your thumb with your right hand on the right side against the mudguard, pull lightly on the wheel with your other fingers and press 'Reset Offset' in the service menu with your left hand, or calibrate in the user menu. In the latter case, however, you cannot see how the voltage value changes.
V2: Sit on the top tube, pull the right brake and push the Stromer slightly backwards with your feet and calibrate or press Reset Offset. It is best to go to the service menu beforehand to be able to observe the 'voltage' value. It should be about 0.03 to max. 0.05 V above the 'offset' value.
V3: Sit on the Stromer, feet NOT on the pedals, calibrate.