The wattage on an e-bike motor sticker is the most widely misread number in the industry. A 750W marking does not mean the motor delivers 750W continuously — and on most North American hub units it does not mean the motor is specified to survive a 750W thermal load at all. Meanwhile a 250W mid-drive in a well-matched European commuter can out-climb a badly geared 500W hub bike on the same gradient, because power at the motor is not power at the road.
For an OEM buyer the power-class decision is really three decisions fused into one: what the destination market's law permits, what the duty cycle physically demands, and which winding and controller pairing the factory can actually supply at your order quantity. Get the order of those three wrong and the result is a container of bikes that cannot be registered, or a field-failure rate that eats the margin on the whole programme.
This guide is written from the supplier side of that decision. The numbers below are the real platform specifications from our own commuter, fat-tyre, mountain, folding and scooter lines, plus the motor and controller parameter sheet we quote against — so you can see how a legal class converts into a winding spec, a battery voltage, a controller current limit and a price.
Continuous Watts vs Peak Watts: The Number Behind the Sticker
Every motor has two ratings that matter and one that is mostly marketing. Continuous (nominal) rating is the power the motor can dissipate as heat indefinitely without the winding insulation degrading. Peak rating is a short-duration figure, typically sustained for somewhere between ten and thirty seconds, limited by the controller's current ceiling and the thermal mass of the stator. The sticker number is usually one of these, printed without saying which, which is why two motors both marked "750W" can differ by a factor of two in real thermal capability.
The honest way to compare is to ask for efficiency and thermal data rather than a single watt figure. Our motor and controller family is quoted at 80–92% peak efficiency, with each matched pair dyno-tested at five load points before shipping and the test report included in every production batch. That gives you a curve, not a headline number: you can see where the efficiency plateau sits and how quickly it falls off past it.
Three specification details tell you more than the wattage ever will:
- Magnet grade. We build with N38SH and N40H neodymium, both high-temperature rated. A cheaper N35 magnet loses field strength as the stator heats, so the motor quietly derates itself on a long climb — the classic symptom of a bike that feels strong for ten minutes and flat afterwards.
- Winding type. Standard-torque and high-speed windings are available on the same stator and housing. The winding, not the wattage, decides whether the motor is happy at 25 km/h on a loaded cargo bike or at 45 km/h on a fat-tyre bike.
- Controller current limit. A sine-wave FOC controller can cap phase current well below what the motor could thermally survive, or push beyond it. The motor–controller pair is the real power system, which is why we supply them as matched pairs rather than as separate line items.
The Legal Classes: EU 250W vs US Class 1-2-3
Legally, the wattage number stops being an engineering question and becomes a compliance gate. The two regimes that matter for most export programmes are the EU regime and the US three-class system, and they are not comparable on power alone.
| Market / class | Motor limit | Speed cut-off | Throttle | Practical registration position |
|---|---|---|---|---|
| EU (EN 15194 pedelec) | 250W continuous | 25 km/h assist cut-off | Pedal-assist only (walk-assist permitted) | Bicycle — no licence, no registration, no insurance in most member states |
| US Class 1 | 750W | 20 mph (32 km/h) | No throttle — pedal assist only | Bicycle in most states |
| US Class 2 | 750W | 20 mph (32 km/h) | Throttle permitted | Bicycle in most states |
| US Class 3 | 750W | 28 mph (45 km/h) | Throttle permitted on many state definitions | Bicycle, but age and helmet rules apply in several states |
| Above 750W / beyond 28 mph | Unlimited in practice | — | Either | Falls outside the three-class bicycle definition — moped, motorcycle or off-road vehicle territory depending on state |
Note what the table does not say. The EU has no peak allowance written into the pedelec definition — a motor that briefly delivers 600W during acceleration is still a 250W motor provided its continuous rating is 250W and assist cuts at 25 km/h. The US classes, by contrast, are defined by the motor's rated wattage and the speed threshold, not by a governed peak. That asymmetry is why the same hardware can be sold as a legal EU pedelec and a legal US Class 2 bike with different firmware and a different label, and why the label is the thing that gets checked.
The full certification implications — EN 15194 system testing, UL 2849, ECE R136 for moped-class machines — are set out in our EU vs US certification guide, and the parallel rules for three-wheeled platforms are in the electric tricycle laws guide.
250W: Where the EU Market Lives
The 250W class is not a compromise, it is a design brief, and it rewards bikes built around it. Our city commuter platform is specified exactly to that brief: a 250W or 350W brushless hub motor on 36V or 48V, with 36V 10Ah or 48V 15Ah removable downtube packs, a 35–60 km range in pedal-assist mode, and a 25 km/h EU-compliant top speed that is unlockable to 32 km/h for markets that permit it. Charging is 4–6 hours on a standard 2A charger.
Because the assist budget is small, everything else on the bike has to be efficient. That is why the commuter platform carries Kenda 700×38C puncture-resistant tyres, a 6061 aluminium frame in step-through or high-step form, Tektro mechanical disc brakes on 160 mm rotors with a hydraulic upgrade option, and a 5-level King-Meter LCD. Total weight lands at 22–25 kg with the battery, load capacity 120 kg rider plus 15 kg on the rear rack.
Where the 250W class goes wrong is when a buyer specifies a heavy frame, wide tyres and a tall rider position, then asks the motor to compensate. It cannot: at 250W continuous the energy budget is roughly fixed, and every kilogram and every millimetre of rolling resistance is taken directly out of range. The city commuter guide covers that trade-off in detail.
The same 250W ceiling applies to folding bikes for the EU market. Our folding platform runs 250W or 350W on 36V with a seat-post integrated 36V 8Ah or 10Ah pack, a 25–45 km range, 18–22 kg all-up weight and a folded footprint of roughly 70×60×40 cm — the configuration that makes multi-modal commuting work. See the folding e-bike OEM guide for the hinge and frame considerations.
500–750W: The North American Sweet Spot
North America is where the 500–750W band earns its keep, because the legal ceiling is higher and the terrain and load expectations are different. Our fat-tyre platform is built for the top of that band: a 500W or 750W brushless hub motor on 48V with a high-torque winding, 48V 15Ah or 48V 20Ah integrated frame packs, a 60–80 km range on throttle plus pedal assist, and a 32 km/h Class 2 top speed with a 45 km/h off-road mode.
The supporting specification matters as much as the motor. The fat-tyre platform carries CST or Chaoyang 26×4.0″ all-terrain tyres run at low pressure, Zoom hydraulic discs on 180 mm rotors front and rear, an RST or Zoom front fork with 80–100 mm of travel, reinforced dropouts, a Bafang C965 colour LCD with USB charging, and a Shimano 7-speed derailleur on a 14–28T freewheel. Weight is 28–33 kg with battery, load capacity 150 kg total, charging 5–7 hours at 2A or 3.5–4 hours on a 4A fast charger.
Two practical notes for buyers in this band. First, the 45 km/h off-road mode is a firmware state, not a separate SKU — it must be locked out of the shipped configuration for any bike labelled Class 2, and the lock must survive a customer menu dive. Second, the torque requirement that owners actually notice is not peak watts but low-speed torque on loose surfaces, which is set by the high-torque winding and the controller's phase-current limit rather than by the wattage label. Our fat tyre OEM guide covers the tyre pressure and chassis pairing in detail.
Mountain platforms sit in the same power band but invert the drivetrain choice entirely: our mountain line uses a 500W, 750W or 1000W Bafang M620 mid-drive with a 250W nominal EN 15194 option, on 48V 15Ah or 21Ah downtube packs with Samsung or LG cells, delivering 60–120 km depending on terrain and assist level. That mid-drive decision, and when it beats a hub, is the subject of hub vs mid-drive.
1000W+: Moped Territory and Registration
Above 750W, the US three-class bicycle framework stops applying. A machine that is rated above 750W or that assists beyond 28 mph is no longer a Class 1, 2 or 3 bicycle in the states that define those classes — it becomes a moped, a motor-driven cycle or an off-road vehicle, and the obligations change accordingly: operator licensing, vehicle registration, insurance, and in many jurisdictions a VIN and a compliant lighting and mirror package.
Europe handles the same territory through vehicle type approval rather than class definitions. Machines that exceed the pedelec envelope are certified as L1e mopeds under the applicable regulation, with the whole-vehicle approval covering braking, lighting, noise and electromagnetic compatibility. Our e-moped OEM guide sets out that approval path and what it costs to bring a platform through it.
Commercially, the 1000W+ band is a legitimate and growing segment — but it is a different business from bicycle distribution. The channel is powersports and moped dealers, not bicycle shops; the paperwork includes a title or certificate of origin; and the liability exposure is motorcycle-shaped. If your business plan is bicycle retail, the 1000W+ product belongs in a separate programme with its own compliance file, not as a firmware unlock on your 750W platform.
Power vs Torque: The Spec Buyers Misread
The second most misread number after wattage is torque, usually quoted in newton-metres without saying where. Motor torque at the stator and torque at the wheel are related by the gearing, and on a hub motor the only gearing is the wheel radius itself. That single fact explains most of the confusing comparisons in this category.
- A hub motor's wheel torque scales with wheel size. The same hub in a 26″ wheel delivers more tractive force at the contact patch than in a 29″ wheel, because the lever arm is shorter and the motor turns faster for the same road speed. This is why fat-tyre bikes with 26″ wheels feel strong off the line and why large-wheel commuters need a different winding to feel equivalent.
- A mid-drive's torque is multiplied by the drivetrain. At the motor it may be quoted at 80–95 N·m, but through a 42T cassette in first gear the wheel sees several times that. This is why a 500W mid-drive climbs better than a 750W hub despite the lower sticker. The comparison is legitimate — engineering it into the bike is the design challenge.
- Controller current limit caps torque, not power. Phase current is what produces torque, so a controller with a conservative current ceiling will feel soft even behind a powerful motor. Our sine-wave FOC controllers are programmable for acceleration curve, regeneration strength and speed limit, which lets one motor serve both a gentle commuter and a punchy utility bike.
- Regenerative braking changes the duty cycle. Regen returns energy on descents and in stop-start traffic, but it also loads the controller and adds heat. On a heavy cargo platform it is worth having; on a 22 kg commuter the benefit is marginal against the added complexity.
The drivetrain and controller parameters that convert these relationships into a build sheet — winding KV, cable exit position, connector standard (L1019, Julet or waterproof), magnet grade, display pairing and axle standard (M12 or M14 with flat) — are itemised in our motor controller guide.
How We Verify the Pair Before It Ships
Because the motor and controller are supplied as a matched pair, the verification happens on the pair rather than on the components in isolation. Each combination is dyno-tested at five load points, and the test report travels with the production batch. The motor winding is rated IP65 and the controller IP54–IP65 with a potted option, which matters more than the datasheet suggests: a potted controller survives the condensation cycle of a bike stored outdoors in a cold climate, and a non-potted one does not.
Compliance follows the same logic. Motor and controller assemblies are tested to the relevant electromagnetic compatibility and safety standards — CE, RoHS and EN 15194 — and for complete vehicle certification the pair is submitted as part of the EN 15194 system-level test package rather than as a standalone component claim. Buyers who need UL 2849 for the North American market should plan the system test around the pair for the same reason.
Commercially, the parameters that govern the order are: MOQ 500 units for motors and 200 units for controllers, with a 20–30 day lead time, and the full motor family covering 250W to 3000W at 36V to 72V across geared hub, direct-drive hub and mid-drive types. Custom branding on the motor side cover is available by laser engraving or silkscreen. The order-structure questions — how many variants a container can carry, how tooling affects the minimum — are covered in the OEM buying guide and the custom tooling guide.
Market-by-Market Selection Framework
Pulling the threads together, the selection sequence for a new programme runs in a fixed order. Starting anywhere other than step one is how programmes end up with unregistrable stock.
- Fix the legal class from the destination, not the aspiration. EU pedelec means 250W continuous and a 25 km/h cut-off. US bicycle distribution means 750W maximum and a 20 or 28 mph threshold. Anything above that is a moped programme with a different channel.
- Set the duty cycle. Rider weight, cargo, gradient and daily distance. A 120 kg rider plus 15 kg of rack load over 35–60 km is a commuter brief; 150 kg total on loose surfaces over 60–80 km is a fat-tyre brief; 60–120 km of climbing is a mid-drive brief.
- Choose the winding to match the duty, not the wattage. High-torque for loaded and hilly; high-speed for fast flat running. Same stator, different copper.
- Size the battery to the legal speed, not to the brochure claim. A 48V 15Ah pack on a 750W fat bike gives 60–80 km; the same pack on a 250W commuter gives far more, because the assist budget per kilometre is smaller.
- Pair the controller and set its limits deliberately. Programmable FOC with acceleration curve, regen strength and a speed limit that matches the class label — and confirm the limit is locked in firmware for shipped units.
- Specify the compliance package with the order. EN 15194 system testing for the EU, UL 2849 for the US, and a per-batch dyno report so the field-failure conversation starts from data.
One platform, several powertrain variants, is usually the right commercial structure — the same frame and chassis serving the EU 250W channel and the US 750W channel with a different winding, battery and firmware state. It keeps tooling amortised across both volumes, which is the difference between a viable first order and one that never gets past the sample stage. The parallel version of this framework for three-wheeled platforms, where payload rather than speed usually drives the decision, is in the cargo tricycle motor power guide.
For a specific market and duty cycle, our engineering team will propose a motor, winding, controller and battery combination against your target class and quote it with the dyno data attached. Send the destination, the legal class you intend to label to, and the rider and cargo weights — those three inputs are enough to start.
Get a Motor Recommendation for Your Target Market
Tell us your target markets, terrain, rider weight assumptions, and product category. We will recommend the power class, motor architecture, and battery pairing, with the certification path (EN 15194, UL 2849, or eMark) for each market.
