How E-Bike Motors Work: A 1200W Guide to Torque, Volts, and All-Terrain Power

You’ve seen them everywhere: rugged, moped-style electric bikes with fat tires and aggressive frames. They look like they’re built to handle anything. But when you look at the specs, you’re hit with a wall of numbers: 750W, 1200W peak, 48V, 13Ah, 99Nm…

What does any of that actually mean?

Welcome to the classroom. I’m here to be your guide, a mentor to help you look past the marketing and understand the physics of what makes a high-performance e-bike tick. We’re going to find out what separates a cool-looking “toy” from a genuine all-terrain utility vehicle.

To make this real, we need a “specimen” to deconstruct. We’ll use the Jasion RetroVolt as our case study. Why? Because its specs are a perfect example of this high-power class: a 1200W peak motor, massive 99Nm of torque, a 48V battery, and a 450lb load capacity.

Don’t worry, this isn’t a sales pitch. This is a teardown. By the end of this, you’ll be able to look at the spec sheet of any e-bike and know exactly what it’s built for.

Let’s get our hands dirty.

Part 1: The “Holy Trinity” of Power (And Why Torque is King)

When you twist the throttle, three things work together to make you go: the motor, the battery, and the controller. But most beginners make the mistake of only looking at one number: Watts.

Let me tell you a secret: for most riders, especially on heavy-duty or all-terrain bikes, Watts isn’t the most important number. Torque is.

1.1 Torque (The “Shove”) vs. Speed (The “Sprint”)

• Torque (measured in Newton-meters, or Nm): This is the “shove.” It’s the raw, twisting force that gets you moving from a dead stop. It’s what rips you up a steep hill.
• Watts (or Horsepower): This is what keeps you moving fast once you’re already going.

Think of it this way: a massive tractor has incredible torque (it can pull a plow through hard soil) but very low top speed. A Formula 1 car has incredible horsepower (insane top speed) but would spin its wheels trying to pull a plow.

Our RetroVolt example claims 99Nm of torque. This is a huge number for an e-bike. This 99Nm is what allows that bike to (a) accelerate a heavy rider (up to 450lbs) from a standstill and (b) climb a steep hill without flinching.

If you are a heavier rider, live in a hilly area, or plan to ride on soft surfaces like sand or snow, shop for torque first. A high-torque bike will feel powerful and responsive. A low-torque bike, even with a high “watt” rating, will feel sluggish and struggle under load.

1.2 The Motor (The “Engine”): Nominal vs. Peak

Okay, now we can talk about Watts. The motor is the engine that converts electricity into that twisting torque. You’ll almost always see two numbers:

• Nominal Power (e.g., 750W): This is the motor’s “cruising speed.” It’s the power it can put out continuously without overheating. This is your all-day, reliable-workhorse number.
• Peak Power (e.g., 1200W): This is the motor’s “sprint” mode. It’s the absolute maximum power the motor can deliver for short bursts—think accelerating from a stoplight or powering over a single, steep obstacle.

A bike with a 750W nominal / 1200W peak rating, like our example, is built for power on demand. The 750W is for cruising, but the controller can call on that 1200W “sprint” for a few seconds when you (or the pedal-assist sensor) demand it.

Most of these bikes use Brushless DC (BLDC) hub motors. All you need to know as a rider is that “brushless” is fantastic. Unlike older brushed motors, there are no physical parts grinding against each other to deliver power. This means three huge wins for you:
1. Higher Efficiency: More of the battery’s juice becomes motion, not wasted heat.
2. Zero Maintenance: No brushes to wear out and replace.
3. Longer Life: They are incredibly durable.

1.3 The Battery (The “Fuel Tank”)

The motor is thirsty. The battery is its “fuel tank.” But again, the spec sheet is confusing. 48V? 13Ah? Let’s make it simple.

Forget amp-hours for a second. Let’s start with Voltage (V).

• Voltage (V) = The “Push” or “Pressure” of the electricity.
• Amp-Hours (Ah) = The “Size” of the tank, or endurance.

Think of electricity like water in a hose. Voltage is the pressure you’re squeezing the nozzle with. Amp-Hours is how much water is in the tank behind you.

A high-voltage system (like 48V) delivers power more forcefully and efficiently than a lower-voltage (36V) system. It gives the bike that “punchy,” responsive feel. It allows the motor to access its peak power (1200W) more readily.

To find the true size of your fuel tank, you multiply the two:
Volts (V) x Amp-Hours (Ah) = Watt-Hours (Wh)

For our RetroVolt example: 48V x 13Ah = 624Wh.

This “624Wh” is the number you should use to compare fuel tanks. A 624Wh battery will always have more range than a 500Wh battery, assuming all else is equal. The 70-mile range claim is based on using the lowest level of Pedal Assist (PAS) on flat ground. If you’re using the throttle-only (“moped mode”), you should expect significantly less.

The fact that it’s a removable lithium-ion battery is a massive convenience. It means you can park the bike and take the “fuel tank” inside to charge, which is essential for security and convenience.

Part 2: Building the “All-Terrain” Platform

Okay, so we have a high-torque motor and a high-pressure fuel tank. We’re ready to fly. But all that power is useless if you can’t control it. That’s where the rest of the bike comes in.

2.1 The Frame: Why “Heavy” Can Be Good

The original article mentioned the RetroVolt’s frame is high-carbon steel. This isn’t a mistake.

In the world of racing bikes, steel is “heavy” and “bad.” But we’re not racing. We’re building an all-terrain utility vehicle. For this job, high-carbon steel is a feature. * Strength & Durability: It’s incredibly strong and can handle abuse, vibration, and heavy loads. * High-Capacity: This is what allows a bike like this to have a 450-pound weight capacity. An aluminum or carbon fiber frame built for that load would be astronomically expensive. * Vibration Dampening: Steel naturally absorbs some high-frequency road buzz, making for a slightly smoother ride.

This is a workhorse frame, not a racehorse frame. It’s built to last and carry a load.

2.2 Full Suspension: More Than Just Comfort

Most people think suspension is just for comfort. On an all-terrain e-bike, it’s for traction.

Look at this photo of the RetroVolt’s rear suspension system.

Imagine you didn’t have that. You hit a bump on a gravel road. The rear wheel, which is powered by your 1200W motor, leaps into the air for a split second. What happens?
1. You lose all your power. The motor is just spinning in the air.
2. You lose all your traction.
3. When the wheel lands, it slams down, potentially skidding and causing you to lose control.

A full suspension system (front forks + rear shocks) solves this. It works to keep the tires glued to the ground. As the frame moves up, the wheel is “pushed” down by the suspension to stay in contact with the trail.

More contact = more traction.
More traction = all that motor torque (99Nm!) can be transferred to the ground instead of being wasted.

Part 3: The Contact Patch (Tires & Brakes)

Finally, let’s talk about the two most critical safety features on the bike, which are also essential for all-terrain performance.

3.1 Fat Tires: The Physics of “Floating”

The 20” x 4” fat tires aren’t just for looks. They are a core part of the bike’s engineering. They create a massive “contact patch”—the amount of rubber touching the ground at any time.

This giant patch does two things:
1. Floatation: On soft surfaces like sand, snow, or mud, a skinny tire digs in and gets stuck. A fat tire, especially at a lower air pressure, “floats” on top.
2. Grip: On gravel or trails, more rubber on the ground means more grip for acceleration, braking, and cornering.

They also act as a secondary suspension system, soaking up small vibrations and bumps before they even get to your frame’s suspension.

3.2 Disc Brakes: Non-Negotiable Stopping Power

This is simple. A heavier bike (steel frame + motor + battery) plus a heavier rider (up to 450lbs) moving at high speed (up to 30mph) creates a massive amount of momentum.

You need to be able to stop.

Dual disc brakes are the only answer. Unlike old-fashioned rim brakes (which squeeze the wheel), disc brakes grab a dedicated rotor at the center of the hub. They are more powerful, dissipate heat better, and—most importantly—work just as well in rain, mud, and snow.

Your Graduation: From Specs to System

So, what did we learn?

A truly capable all-terrain e-bike isn’t just one magic component. It’s a system.

• You can’t have a high-torque motor (99Nm) without a strong frame (450lb capacity) to handle the forces.
• You can’t use that torque on a trail without full suspension to keep the wheel on the ground.
• You can’t have a powerful motor or suspension without fat tires to provide the grip and float needed to use them.
• And you can’t have any of it without a high-pressure battery (48V) to feed the beast and powerful disc brakes to tame it.

Now, when you’re shopping, you’re not just a beginner looking at cool pictures. You’re a graduate. You can look at a spec sheet and see the system behind the numbers. You can deconstruct any bike and understand what it was truly built to do.

Class dismissed.