Why programme a Bafang M620?
The M620 Ultra ships with "standard" firmware that suits most users: 5 assist modes, progressive ramp-up, 25 km/h cutoff. But these settings are compromises. Depending on your usage (urban, gravel, trekking, private track), you can radically fine-tune the feel by programming the motor.
The official tool: Bafang Config Tool
Freely downloadable from the Bafang website (BPS-Tools), Windows only. Requires:
- Bafang USB programming cable (~€25) or USB-OTG smartphone from 2024 onwards
- Motor powered (battery connected)
- FTDI drivers installed
Connection via the motor's diagnostic port (under the protective cover of the main hatch).
Programmable parameters
### Assist modes (5 levels) For each level (0 = no assistance, 5 = max), you set:
- Current Limit (%): motor intensity allowed (0-100%)
- Speed Limit (%): cutoff speed relative to legal max speed
- Start mode: soft / moderate / aggressive launch
Typical before/after example for trekking use:
| Level | Stock | Optimised trekking |
|---|---|---|
| 1 | 25% current, 60% speed | 30% current, 100% speed |
| 2 | 40% / 70% | 45% / 100% |
| 3 | 60% / 80% | 60% / 100% |
| 4 | 80% / 90% | 80% / 100% |
| 5 | 100% / 100% | 100% / 100% |
Result: you keep assistance all the way to 25 km/h at every level (instead of losing it at 15 km/h in level 1).
### Torque curve (Pedal Assist) The M620 uses a torque sensor to modulate assistance. The default curve is "linear": you push 2× harder → motor assists 2× more. You can switch to:
- Quadratic: non-linear assistance, soft launch then explosive torque under effort
- Logarithmic: aggressive launch, assistance that eases off at high effort (energy saving)
Speed cutoff (Speed Cutoff) EU public roads: must stay at 25 km/h. Any programming beyond that makes your bike illegal (moped registration required, insurance, etc.).
Private track / outside EU: you can push up to 45 km/h on the M620. For private racing, off-road tracks, or simply non-EU countries.
The legal framework — important
In France and the EU:
- e-Bike = max 250 W nominal + max 25 km/h assistance + pedal cutoff
- Beyond that = moped, mandatory registration, motorcycle helmet, insurance, plate, AM licence
If you derestrict an M620 on public roads:
- No insurance cover in case of accident
- Fine up to €30,000 + licence suspension (article R.317-8)
- Bike confiscation possible
Recommendation: keep a "public road 25 km/h" profile in programme 1, a "private track 35-45 km/h" profile in programme 2 if you do trail or private outings. You can switch via the Bafang DP-C18 display (programmes 1/2/3).
