SpeedBox 3.1 B.Tuning is a third-generation untuning module designed for electric bikes fitted with Bafang Max Drive M300, M400 or M420 motors with 4-pin connectors. It removes the 25 km/h assistance limit, offering assistance up to higher speeds (around 35 km/h). This Bluetooth version also lets you control and customize the module's settings via the SpeedBox App on your smartphone.
Key Features
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Remove assistance limit: Eliminates the 25 km/h restriction.
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Flexible activation/deactivation: Activation via the WALK function, a specific key sequence or the SpeedBox App.
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Actual data display: Current speed, maximum speed, average speed, mileage and range displayed correctly.
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Simple installation: original connectors for plug & play installation without modifications.
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Control via SpeedBox App: Control and customize module settings via Bluetooth.
Technical Description
| Specification | Detail |
|---|---|
| Type of Use | Tuning e-bike Bafang Max Drive M300 / M400 / M420 (private use recommended) |
| Motor Compatibility | Bafang Max Drive M300 / M400 / M420 with 4-pin connector |
| Screen compatibility | System-compatible Bafang screens |
| Activation/Deactivation | WALK function, key sequence ↑↓↑↓, or via SpeedBox App |
| Activation indication | 99 km/h display briefly |
| Indication of deactivation | Display 25 km/h briefly |
| Recommended max. speed | Unlimited (≈ 35 km/h recommended) |
| Actual speed display | Yes |
| Correct distance | Yes, after the countdown at the end of the journey |
| Installation | Plug & play with original connectors |
| Practical notes | Do not switch on/off while riding; leave the bike powered up to 0.0 km/h before switching off. |
| Incompatibilities | Not compatible with standard sensor (not 4-pin), ABS systems |





