How we picked
Battery watt-hours decided the order, because energy capacity is the only range input a manufacturer cannot present flatteringly. After that came efficiency— tire width, weight and sensor type change how many watt-hours a mile actually costs, which is why the 672 Wh bike on this page can outlast the 692 Wh one in the right conditions. Then certification and trim clarity: a big pack is only good news if the listing tells you which pack you are buying. We have not ridden every one of these; this is exactly what we do instead.
Watt-hours, and the number that turns them into miles
A watt-hour is one watt drawn for one hour. Your battery’s capacity is volts multiplied by amp-hours — a 48 V, 20 Ah pack is 960 Wh. That is the whole tank. What decides your range is how many watt-hours each mile costs you, and that varies more than most buyers expect:
- 10–15 Wh per mile— pedaling genuinely, low assist, city tires, flat ground.
- 20 Wh per mile— our standard planning figure for throttle-heavy riding on fat tires. Use this one unless you know you ride differently.
- 25–30 Wh per mile— throttle only, a heavier rider, hills, headwind, cold weather, or all of them at once.
Run the four bikes here through the 20 Wh figure and the picture gets honest fast. The SASIKEIBIKE’s 1,040 Wh gives roughly 52 miles. The Heybike Ranger S’s 692 Wh gives roughly 35, the GoTrax F3’s 672 Wh roughly 34, and the Aipas A2’s 614 Wh roughly 31. Their claimed figures are 70, 55, 60 and 62 miles respectively. Both sets of numbers are on the listings; only one of them is a planning figure. Our range guide works through how to measure your own watt-hours per mile in a week of ordinary riding.
Efficiency is the half of range nobody advertises
Two bikes with the same battery can differ by a third in real range, and the reasons are physical rather than mysterious.
Tire width and pressure.A 4-inch fat tire at 15 psi has a large contact patch and high rolling resistance. The same bike on city tires at 45 psi uses noticeably fewer watt-hours per mile. It is the single biggest efficiency lever you control, and it is free — see our tire pressure guide.
Sensor type. A cadence sensor delivers a fixed amount of power the moment the pedals turn, whether you need it or not. A torque sensor delivers power in proportion to your effort, which means it stops spending watt-hours the instant you stop working. That is why the F3, the lightest and only torque-sensor bike here, punches above its capacity.
Weight and speed.Air resistance rises with the square of speed, so a Class 3 bike cruising at 28 mph burns dramatically more per mile than the same bike at 18. If range is your priority, the cheapest thing you can do is ride slightly slower.
Two batteries or one big one?
Once you are over about 700 Wh, a second battery often beats a bigger one. A spare pack is dead weight you leave at home on short days and carry on long ones, it charges while the first is in use, and it gives you a fallback when the original pack ages out in a few years. A single enormous pack is simpler, but it is also a single point of failure and it is heavy on every ride, including the three-mile ones.
The catch is compatibility: a replacement or range-extender pack has to match your bike’s voltage, connector and mount, and a mismatched charger is a genuine fire risk rather than a theoretical one. Our battery roundup covers what to match and which certification to insist on.
Check the trim before you buy
More than any other spec, battery capacity varies inside a single model name. The Heybike and GoTrax ranges have both had smaller-battery versions in circulation, and the Aipas A2 describes peak and rated wattage inconsistently between listings. The battery number in the title is not always the battery in the box for the variant you selected — a lesson the now-discontinued Sohamo S3, sold under one name in both 720 Wh and 960 Wh trims, taught this bracket the hard way.
Before you check out, confirm three things on the listing: the watt-hours or the volts and amp-hours for the exact variant in your cart, whether the pack carries UL 2271 or UL 2849 certification, and whether a second battery is available for that model at all. If a listing quotes only “big capacity” and a mileage claim, treat the mileage claim as marketing and move on.
