How Fast Do Ebikes Go?
Three different numbers get quoted as an ebike's speed, and only one of them decides how long your commute takes. It is not the one printed on the box.
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Ask how fast an ebike goes and you will get three answers, all of them technically correct, because the question hides three separate numbers. There is the speed at which the motor stops helping. There is the fastest the bike will physically travel. And there is the speed you actually average across a real ride, which is the only one that decides whether you make it to work on time.
Nearly every argument about ebike speed comes from swapping one of those numbers for another. A 28 mph Class 3 bike does not travel at 28 mph. A 20 mph Class 2 bike is not limited to 20 mph. And a listing promising 40 mph is describing a machine that is not a bicycle in any legal sense, whatever the product photos suggest.
Three speeds, and only one of them matters daily
Get these three straight and the rest of the topic stops being confusing.
- Assist cutoff
- The speed at which the controller stops feeding the motor. 20 mph for Class 1 and 2, 28 mph for Class 3. A legal ceiling, not a physical one.
- Unassisted top speed
- How fast the bike will roll on your legs plus gravity. Limited by drag, gearing, and how brave you are. 30 to 35 mph on a moderate descent is routine.
- Real average speed
- Total distance divided by total time, including every light, turn, and pause. Typically 12 to 17 mph. This is the number that predicts your arrival time.
The gap between the second and third numbers is enormous, and it is where most buyer disappointment lives. Someone upgrades from a 20 mph bike to a 28 mph bike expecting their 30 minute commute to become 21 minutes, and it becomes 27 minutes, because the extra 8 mph only applies to the fraction of the ride spent at cruising speed on open road. If your route is stoplights and turns, you bought 8 mph you will almost never use.
What the assist cutoff actually does
The cutoff is a software rule inside the controller. It reads wheel speed and tapers motor current as you approach the limit, then holds power at zero above it. It is not a brake, a governor, or a rev limiter. Nothing resists you at 21 mph on a Class 2 bike; the motor simply stops contributing and you are on a heavy bicycle.
How that cutoff feels varies a lot between bikes, and it is worth paying attention to on a test ride:
- A hard cutoff yanks the power away within a mile per hour of the limit. It feels like hitting a wall, and it is common on cheap cadence-sensor bikes. You end up oscillating around the cutoff speed all ride.
- A tapered cutoff rolls power off over the last 3 to 4 mph. Good mid-drive systems do this well, and the transition to your own legs is nearly invisible. This is the single biggest reason a quality drive system feels faster than a cheap one at the same rated speed.
The cutoff also applies to the throttle where one exists. A throttle on a Class 2 bike stops working at 20 mph regardless of how hard you pull it, and in most states that permit throttles on Class 3 bikes, the throttle itself is still capped at 20 while pedal assist continues to 28. Our throttle guide covers how the different throttle types behave near the limit, and the full legal picture is in ebike classes explained.
How fast an ebike goes with the motor doing nothing
Above the cutoff you are riding a bicycle that weighs 55 to 75 lb. That is not as bad as it sounds. Weight barely affects flat-ground speed, and on a descent it actively helps, because gravity scales with mass while drag does not. A heavy ebike coasts downhill faster than a 17 lb road bike with the same rider.
Three things decide how far past the cutoff you can go.
Aerodynamic drag
By 20 mph, drag is already most of the resistance you feel, and it grows brutally from there. Drag force rises with the square of speed, and because power equals force times speed, the power you need to overcome it rises with the cube. Upright riding position, wide flat-bar handlebars, panniers, and 4 inch fat tires all make this worse. A fat tire cruiser and a drop-bar electric road bike with identical motors will differ by 5 mph or more at the top end purely on shape.
Gearing
Many ebikes are geared for the assisted band, not for what happens above it. On a bike with a small chainring and a 7 speed freewheel, you will spin out around 24 to 26 mph, meaning your legs cannot turn the cranks fast enough to add anything. Class 3 bikes usually fix this with a larger chainring or a wider cassette, which is why a Class 3 bike often feels faster above 28 mph than a Class 2 bike does above 20. If you plan to pedal past the cutoff regularly, look at the chainring size, not the motor. Our explainer on what ebike gears actually do goes into the ratios.
Motor drag, on some bikes
Motor type changes how the bike coasts:
- Geared hub motors have an internal freewheel clutch. Above the cutoff the motor disconnects and the wheel spins free. No penalty.
- Direct drive hub motors have no clutch. The magnets pass the stator whether or not current flows, producing cogging drag you can feel as a faint pulsing resistance. It costs a few watts at low speed and a meaningful amount above 25 mph.
- Mid-drives drive through the chain and freewheel at the cassette, so they coast like a normal bike.
This is one of the practical differences covered in mid-drive versus hub motor. If you want a bike that feels good above its cutoff, avoid direct drive.
Your real average speed, and why it is the only one that matters
Average speed is total distance divided by total elapsed time, including the 40 seconds you spent at a light. It is always dramatically lower than cruising speed, and it is remarkably stable per route. Once you have ridden a commute a dozen times, your average barely moves no matter how hard you push, because the time is being eaten by things you cannot pedal through.
| Route type | Typical average | What eats the time |
|---|---|---|
| Downtown core, dense signals | 9 to 12 mph | Lights, pedestrians, door zone caution |
| Urban street, lights every few blocks | 11 to 14 mph | Stop and restart cycles |
| Hilly residential | 12 to 15 mph | Climbing, plus braking on the way down |
| Suburban path, few crossings | 15 to 18 mph | Path speed limits, shared users |
| Suburban arterial on a Class 3 | 16 to 20 mph | Signals, but long open stretches between |
Swipe sideways to see all columns →
Look at what the table implies. Moving from a 20 mph bike to a 28 mph bike on a downtown route changes almost nothing, because you rarely reach 20 in the first place. On a suburban arterial with half mile gaps between lights, the same upgrade is worth several minutes on a 10 mile ride. Buy the cutoff that matches your route shape, not the biggest number available.
The other lever is stops. Each full stop and restart costs roughly 15 to 25 seconds of elapsed time on a heavy bike once you include deceleration, waiting, and getting back up to speed. A route with 20 signals gives away five to eight minutes before you have pedaled anywhere. Choosing a route with fewer crossings beats buying a faster bike almost every time.
Why holding 28 mph costs roughly twice the power of 20
This is the single most useful piece of physics in ebikes, and it explains half the complaints about range.
Aerodynamic drag force rises with the square of speed. The power required to push through that drag rises with the cube, because power is force multiplied by velocity. Go from 20 mph to 28 mph, a factor of 1.4, and the aerodynamic power alone rises by 1.4 cubed, which is about 2.7 times. Rolling resistance and drivetrain losses scale more gently, so the total power at the wheel roughly doubles rather than tripling.
In practical terms, an average rider on an upright commuter ebike needs somewhere around 200 to 250 watts at the wheel to hold 20 mph on flat ground with no wind. To hold 28 mph on the same bike, the requirement lands closer to 450 to 550 watts. The rider contributes maybe 100 to 150 watts of that continuously, so the motor is being asked to more than double its output.
Two consequences follow directly:
- Fast ebikes have poor range and always will. A 720 Wh battery that delivers 45 miles at a steady 18 mph may deliver 22 to 25 miles at a steady 28 mph on the same route. The battery did not shrink. The power draw doubled. This is why the bikes in our longest range guide are almost never the fast ones.
- Motor wattage buys acceleration and hills more than top speed. Doubling motor power does not double your speed; it raises your top speed by roughly the cube root of the power increase, which is about 26 percent. A 1000W motor is not twice as fast as a 500W motor. It is meaningfully quicker off the line and much better on grades. That mechanism is unpacked in ebike motor wattage explained.
The same math is why a headwind hurts so much more than it seems it should. A 10 mph headwind while you ride at 20 mph means the air is passing you at 30 mph, and the power requirement is set by that 30, not by your 20. Riders routinely blame the battery for a bad range day when the real culprit was a windy afternoon.
What 30 mph, 35 mph, and 40 mph claims really mean
Search results are full of bikes advertising numbers above the Class 3 ceiling. Those claims almost always come from one of four places.
- Unrestricted mode. The bike ships limited to 20 mph for compliance, and the display has a menu that removes the cap. The marketing quotes the unrestricted number and the compliance sticker quotes the legal one. Both are printed on the same page.
- Downhill and tailwind. The figure is a coasting or assisted-descent number with no grade stated. Every ebike does 35 mph downhill. That is not a spec.
- No rider weight given. Speed claims without a stated test weight are close to meaningless. The federal 20 mph definition of a low-speed electric bicycle specifies a 170 lb rider on level ground for exactly this reason.
- It is not an ebike. A machine that sustains 35 or 40 mph under motor power has a motor well past 750W and assist well past 28 mph. In the states using the three-class system, it is a moped, a motor-driven cycle, or a motorcycle, with the licensing, registration, and insurance that go with those categories, and no legal access to bike lanes or paths.
The last one is the one that costs people money. Insurers deny claims on this basis, and a collision while operating an unregistered motor vehicle is a very different legal position than the same collision on a bicycle. We go through the full picture in what a 50 mph ebike actually is, and cover which fast bikes stay inside the law in the fastest electric bikes you can actually buy.
What actually makes you faster on an ebike
If the goal is arriving sooner rather than seeing a bigger number on the display, the levers are not the ones people reach for.
- Pick a route with fewer stops. Worth more minutes than any component change. A parallel street with half the signals beats a faster bike on the busier one.
- Fix your position and your tires. Drag is the dominant force above 18 mph, and you own the largest part of it. Dropping the bars, narrowing the bars, or moving from 4 inch fat tires to 2.2 inch commuter tires each buy real speed for no battery cost. Tire pressure at the top of the printed range cuts rolling resistance too.
- Get a torque sensor, not more watts. Torque sensing responds to pedal pressure instantly, which is what makes a bike feel quick out of a light. Cadence sensing waits for the cranks to turn, then ramps. Across a route with 20 stops, that difference is worth more elapsed time than 250 extra watts.
- Carry enough battery to avoid voltage sag. Controllers reduce output as pack voltage falls, so a bike on its last quarter charge is genuinely slower. If you routinely finish rides near empty, you are riding the slow end of your bike most days. See 36V vs 48V vs 52V batteries for why higher voltage packs hold speed better under load.
- Buy Class 3 only if your route rewards it. Long open stretches and traffic moving at 35 mph make the case. Bike paths and dense downtowns do not, and Class 3 is banned from many paths anyway. The trade-offs are in our Class 3 explainer.
The honest summary is that ebike speed is bounded by air, not by motors. Every manufacturer is fighting the same cubic power curve, so the differences between bikes at the top end are small, while the differences in how quickly they get back to cruising speed after a stop are large. Optimize for the second one.
If you are still deciding what to buy, start with the class system, since it sets your legal cutoff and your path access before anything else. From there, what electric bikes actually cost maps the price brackets onto the components that hold speed.