How to choose an e-bike
Five specs decide how a bike actually feels. The rest is detail. Here is what each one does, and the number that matters.
1. Torque sensor or cadence sensor
This is the single biggest difference in ride feel, and it is the spec most listings bury. A cadence sensor only knows whether the pedals are turning, so the motor surges to a set power level and holds it — it feels like a scooter you happen to be pedalling. A torque sensor measures how hard you push and multiplies it, so the bike feels like a strong version of a normal bicycle.
Neither is wrong. Cadence suits riders who want to be carried. Torque suits riders who want to ride. But a cheap bike with a torque sensor often feels better than an expensive one without.
2. Torque, not watts
Watts get advertised; newton-metres get you up the hill. Nominal wattage is a loosely regulated number and peak wattage is nearly a marketing figure. Torque (Nm) is the one that predicts hill climbing and loaded starts. Roughly: 40–60 Nm is fine on flat ground, 60–80 Nm handles most hills, and 80+ Nm is what you want for cargo, steep terrain, or a heavy rider.
3. Watt-hours, not "range"
Claimed range is the least trustworthy number in the industry — it is usually measured by a light rider on the lowest assist on flat ground with no wind. Watt-hours (Wh) is the honest capacity spec. Wh = volts × amp-hours, so a 48V 15Ah pack is 720Wh.
A usable rule of thumb: most riders get 15–25 Wh per mile depending on assist level, terrain, and weight. A 720Wh battery is therefore a realistic 30–48 miles, not the 60+ on the box. We list both the claim and the raw Wh so you can do that maths yourself.
4. Mid-drive or hub
A rear hub motor pushes the wheel directly. It is cheaper, simpler, quieter to maintain, and works fine on flat and rolling ground. A mid-drive puts power through the chain and gears, so it multiplies torque in low gear — much better on sustained climbs and under load, and it centres the weight. It costs more and wears chains faster.
Mid-drive is worth it for steep hills, cargo hauling and trail riding. For a flat commute, a good hub motor is the better value.
5. Weight and payload
Two numbers, both routinely ignored. Weight decides whether you can get the bike up a step, onto a rack, or home after a flat battery — anything over about 70 lb is a two-person lift. Max total load (rider plus cargo plus bike accessories) is a real engineering limit, and on some bikes it is lower than buyers expect.
Watch for weights quoted without the battery. Several brands do this; a battery is 7–10 lb. We normalise to total weight and note it where the manufacturer split the figure.
Why everyone suddenly talks about UL certification
A lithium-ion cell that is damaged, defective or charged with the wrong charger can go into thermal runaway: a self-feeding reaction that produces intense heat, toxic gas and fire that is very hard to put out. It starts without warning. In a flat with the bike charging by the only door, that is a deadly combination, and New York City learned this the hard way through a run of fatal fires in buildings where delivery riders charged cheap, uncertified batteries indoors.
New York responded with Local Law 39 of 2023, in force since 16 September 2023, which bans the sale, lease, rental and second-hand distribution of uncertified e-bikes, e-scooters and batteries in the city. UL Standards & Engagement has since reported e-bike fire deaths in the city falling. That law is why the whole industry started advertising certification at once — not a marketing fashion, a market requirement.
The three numbers, and which one you want
- UL 2849 — the whole electrical system: motor, controller, wiring, charger and battery, tested together. This is the one to want.
- UL 2271 — the battery pack alone. Better than nothing, but it says nothing about the charger or controller that might mistreat it.
- UL 2272 — e-scooters and hoverboards. Not e-bikes; you will see it quoted anyway.
A properly UL 2849-certified bike has a battery meeting UL 2271 as part of that evaluation, so 2849 is the stronger claim and it includes the other. A bike advertising only UL 2271 is telling you the pack was tested and the system around it was not.
Read the verb, not just the number
Three words get used as if they were the same thing, and they are not:
- Certified — an accredited lab tested it and the mark is maintained with follow-up inspection.
- Recognized — a component-level mark, meant for a part inside a larger product, not a finished-product claim.
- Compliant or tested to — the manufacturer says it would pass. Nobody independent necessarily checked.
We quote each brand’s own wording on its bike pages for exactly this reason, and link where they said it. We are repeating a manufacturer’s claim, not verifying it — you can look up a specific model in UL’s Product iQ database, which is the public record.
What this means when you are shopping
Of the 39 bikes here, 14 carry a full-system UL 2849 claim across the maker’s range, 10 come from brands saying most of their line is certified, 11 claim only a certified battery, and 4 publish nothing we could find. Filter for it on the comparison table.
Two practical habits, whatever you buy: use the charger that came with the bike, and do not charge it overnight, in a doorway, or against an exit.
A word on classes
- Class 1 — pedal assist only, cuts out at 20 mph. Allowed on most bike paths and many trails.
- Class 2 — adds a throttle, still capped at 20 mph. The most common US configuration.
- Class 3 — pedal assist to 28 mph. Fastest for commuting, but restricted from some paths and trails.
Many bikes ship in a lower class and unlock to a higher one in the settings menu. We list both the shipped class and what it unlocks to.
Federal or state? Both, doing different jobs
This trips almost everyone up, so it is worth separating.
- Federal law (15 U.S.C. § 2085) defines a low-speed electric bicycle as having fully operable pedals, a motor under 750W, and a motor-only top speed under 20 mph with a 170 lb rider. Its job is to say what the thing is: clear that bar and it is a consumer product regulated like a bicycle, rather than a motor vehicle. It governs how a bike is built and sold.
- The Class 1/2/3 system is state law, not federal. Most states have adopted some version of it, and it governs riding — speed caps, and in some states age or helmet rules.
- Cities, counties and park authorities set the rules for particular paths and trails.
So the 750W figure is a product definition, and the class number is a state riding rule built on top of it. A machine above 750W is not a low-speed electric bicycle federally, which is why it falls outside the class system entirely.
What we would actually check first
Open the comparison table, sort by torque, then filter to torque-sensing bikes in your budget. That single move eliminates most of the bikes that disappoint people, and it takes about ten seconds.