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Graduvex

Real e-bike range: the honest calculation

Brochures promise “up to 120 km”; real e-bike life happens between 25 and 70 km depending on assist, terrain, weight and season. This tool computes a realistic range from observed consumption figures, not the manufacturers’ ideal scenario.

On the battery label: volts × amp-hours (e.g. 36 V × 13.4 Ah ≈ 480 Wh).

The one you actually ride in most of the time, not the special-occasion one.

The dominant profile of your rides, not the single worst kilometre.

You + the bike + luggage. A city e-bike alone weighs 22 to 28 kg.

Cold cuts a lithium battery’s usable capacity by roughly 20%.

Realistic range

31mi

Within the realistic norm for a 500 Wh e-bike in everyday use.

Estimated consumption
10.0Wh/km

The method

Range is just a division: battery capacity (in watt-hours) by what the bike consumes per kilometre. The whole difficulty is estimating that consumption honestly.

We start from a base consumption per assist level — 7, 10 or 14 Wh/km, figures observed in the field — then correct it: terrain multiplies (up to ×1.7 in the mountains), every kilo above 95 kg adds about 0.4%, and cold removes 20% of the battery’s usable capacity.

The result is deliberately cautious: better to arrive with 15% battery than to push 25 kg for the last five kilometres.

In the formula: C is capacity (Wh), b the base consumption (Wh/km), r the terrain coefficient, m the total weight (kg), f = 0.8 in winter conditions.

range (km) = C × f / [b × r × (1 + (m − 95) × 0.004)]

Good to know

  • Brochure “up to 120 km” figures assume Eco mode, flat ground, a light rider, no wind and a new battery: five conditions rarely met at once.
  • Lithium batteries fade with age: expect −15 to −25% after 500 full cycles, about 3 to 5 years of normal use.
  • Pulling away consumes the most: frequent urban stop-and-go pushes you toward the top of the consumption range.
  • Tyre pressure matters: 1 bar below spec can cost 10% of range.
  • The estimate assumes normal pedalling: barely turning the pedals can double consumption.

FAQ

Why is my real range so far from the brochure?

Because the brochure measures the best case: Eco mode, flat ground, 70 kg, 20 °C. Switch to Normal on a rolling route with panniers and consumption doubles — so does range, in the wrong direction. The typical gap between brochure and reality is 40 to 60%.

How do I find my battery capacity in Wh?

It is printed on the battery, sometimes as two numbers to multiply: voltage (36 or 48 V) and charge (in Ah). Example: 36 V × 13.4 Ah ≈ 480 Wh. Beware of product sheets that round generously.

Does cold damage the battery or just reduce range?

Riding in the cold temporarily reduces usable capacity (the chemistry slows down): range comes back with warmth. What actually damages the battery is CHARGING it below 0 °C — charge it indoors in winter.

Is a second battery better than a bigger one?

At equal total capacity, two batteries buy flexibility (carry only what you need, charge one while riding the other) but cost more per watt-hour. One big battery is simpler day to day — and permanently heavier, even for a bakery run.

My display shows a different range: which should I trust?

The display extrapolates your last few kilometres of consumption: it is more accurate than this calculation… as long as conditions do not change. It collapses at the foot of the first climb. This tool gives the realistic average for the whole route; the display gives the instantaneous view.

Does riding with an empty battery harm the bike?

No: the bike simply becomes a bike, just a heavy one. However, storing the battery fully empty for weeks does degrade it. For winter storage, aim for 40–60% charge, cool but frost-free.