How far can an e-bike really go on a charge?
For an average rider pedaling along at a steady casual effort, here's what the physics says — the same rider, the same flat route, only the battery and assist mode changing:
| Battery | Eco | Tour | Turbo |
|---|---|---|---|
| 400 Wh | 75 mi | 38 mi | 32 mi |
| 500 Wh | 93 mi | 48 mi | 40 mi |
| 625 Wh | 117 mi | 59 mi | 51 mi |
| 750 Wh | 140 mi | 71 mi | 61 mi |
165 lb rider + 55 lb Class 1 e-bike, ~100 W of pedaling, mostly flat, computed by the calculator above. Rolling terrain takes about 20% off these numbers; proper hills take 35–40%.
Spec sheets love amp-hours, but Ah alone means nothing without voltage. Multiply them: a 36 V, 13.4 Ah pack is 36 × 13.4 ≈ 482 Wh; a 48 V, 15 Ah pack is 720 Wh. Watt-hours is the number that predicts range, and it's the only fair way to compare two bikes' batteries.
Why turbo mode doesn't halve your range the way you'd expect
In turbo, the motor wants to add 340 W to your 100 — about 436 W of battery draw. But a Class 1 bike stops assisting at 20 mph, and on the flat you hit that wall almost immediately. Pinned at the limiter, the motor throttles back to just 174 W of help (223 W from the battery), and range settles at 40 miles instead of the 48 you'd get in Tour. The place turbo truly devours a battery is where there's no limiter to save you: climbs and headwinds, where the motor runs flat-out for minutes at a time. That's also why the same bike sold as a Class 3 — assisting to 28 mph — gives up range on the commute: more speed, cubed air resistance, no shelter from the limiter.
What actually drains the battery
In order of what the model shows: speed (air resistance grows with the cube — the last 5 mph cost more than the first 15), climbing (weight × height, no way around it), your own effort (every watt you pedal is a watt the pack doesn't spend — riding one assist level lower is the single cheapest range extender), and system weight including cargo and passengers. Cold weather is the one the physics here doesn't model: lithium packs deliver 10–20% less below freezing, so treat winter estimates accordingly.
A full 500 Wh charge is half a kilowatt-hour — about 8¢ at a typical US electricity rate. Spread over 48 miles of Tour-mode riding, that's roughly 0.17¢ per mile. A gasoline car at 30 mpg costs around 10–12¢ per mile in fuel alone — fifty times more. Charge it every night; the electricity is a rounding error.
Why manufacturer range claims run high
"Up to 100 miles" is not a lie — it's Eco mode, a light rider, a flat windless route, warm weather and a fresh pack, all at once. Manufacturer calculators are tuned the same direction, because they're sales tools. This one has no bike to sell you: the model is the published Martin power equation with a 78% motor efficiency and 90% usable battery, and it still carries an honest ±20% — wind, stops, tire pressure and battery age all push on the answer. Plan trips on the calculator's number in your real assist mode, not the brochure's.
How to stretch your range when it matters
Ranked by effect, all free: drop one assist level (often +30–50% range), slow down 2–3 mph on open stretches, pedal a little harder on the flats and save the motor for hills, keep tires at the pressure our tire pressure calculator suggests (soft tires quietly tax every mile), and start climbs slow instead of letting the motor sprint them. If range anxiety is chronic rather than occasional, the real fix is a bigger pack — the table above shows exactly what each 125 Wh buys.