In short: advertised range is measured in ideal conditions. In real life what counts is Wh ÷ consumption: on the flat you use about 8–10 Wh per km, uphill or into the wind as much as 15–20.
Why advertised range does not add up
«Up to 120 km» usually means: lowest assist level, perfectly flat, a light rider, no wind and 20 °C. It is possible, but rare. To know how far you will really go you need a simple calculation that works with any spec sheet.
The calculation that really counts
The battery shows voltage (V) and capacity (Ah). Multiply them to get watt-hours (Wh), the energy available. A 36 V, 14 Ah battery holds 504 Wh. Then divide by the consumption of your route.
| Route | Typical use | With 500 Wh | With 750 Wh |
|---|---|---|---|
| Flat, low assist | 7–9 Wh/km | 55–70 km | 85–105 km |
| Mixed city riding | 10–12 Wh/km | 40–50 km | 60–75 km |
| Hills, high assist | 15–20 Wh/km | 25–35 km | 38–50 km |
| E-MTB in the mountains | 20–30 Wh/km | 17–25 km | 25–38 km |
For climbs there is another rule of thumb: an average rider uses about 1 Wh for every 10 metres of climbing at medium assist. A ride with 1,000 m of climbing therefore needs around 100 Wh for the climbing alone.
What reduces range
- High assist level and frequent starts: pulling away from a stop is when the motor uses the most.
- Weight of rider, luggage or children.
- Cold: below 5 °C the battery can deliver 20–30% less.
- Under-inflated or very wide tyres: fat bikes use more.
- Headwind and speeds close to 25 km/h, where air resistance rises sharply.
- An ageing battery: after 500–800 full cycles capacity drops, usually to around 70–80% of the original.
How to make it last longer
- Shift gears as on a normal bike: use easy gears on climbs and when starting, so the motor works less.
- Use high assist only where you need it, on climbs or into the wind, and go back to eco on the flat.
- Check tyre pressure every two weeks.
- Keep the battery indoors in winter and charge it at room temperature.
- For long breaks store it at 40–60%, not empty and not full.
How much battery you need
- Commuting up to 15 km a day: 400–500 Wh is enough, charging every 2–3 days.
- Day trips and mixed use: 500–625 Wh.
- Touring, mountains or heavy loads: 700 Wh or more, or a second battery.
A bigger battery weighs more, about 1 kg extra for every 200 Wh, and costs more. Choose it for the distance you actually ride, not the one you might ride once a year. To learn how to charge and store it, read our battery guide.
