E-bike Specs Explained: A Beginner's Guide to Watts, Volts, and Commuter-Friendly Features

Hello, and welcome. If you’re starting to shop for your first electric bike, you’ve probably been hit with a wall of numbers: 350W, 500W, 36V, 7.8Ah, 14-inch wheels, 20-inch wheels… It can feel less like shopping for a bike and more like preparing for an engineering exam.

You’re not alone. This is the biggest hurdle for most newcomers.

The good news is that it’s all much simpler than it looks. Those numbers aren’t meant to confuse you; they’re the “recipe” for the bike’s performance. As your guide, my goal today is to give you the confidence to read any e-bike advertisement and know exactly what it means for your daily ride.

To make this practical, we’ll use a real-world example as a case study. We’ll look at the specs for a common compact, folding model like the Windone S14, which is typical of what you’d find for urban commuting.

Ready? Let’s decode this together.

The “Big Three” Specs That Define Your Ride

When you boil it all down, your e-bike experience is defined by three things: the motor, the battery, and the resulting range. Let’s tackle them one by one.

1. The Motor: Watts (W) and Power

You’ll see motors advertised in Watts (W), like 250W, 350W, or 750W.

The Common Misconception: Watts = Speed.
The Reality: Watts = Power (or Torque).

Think of the motor’s Wattage not as its top speed (which is often legally limited anyway), but as its strength. This strength is what helps you accelerate from a stoplight and, most importantly, climb hills.

• 250W: The standard in many parts of Europe. It’s gentle, great for flat terrain, and offers the most “bicycle-like” feel.
• 350W - 500W: This is the sweet spot for most North American urban commuting. It’s strong enough to flatten moderate hills and give you a satisfying zip when you start pedaling.
• 750W+: These are powerful motors, often found on fat-tire or “off-road” style e-bikes. They offer thrilling acceleration and can tackle very steep inclines.

Case Study: The Windone S14
Our example bike lists a 350W motor that peaks at 500W. What does this mean?

• 350W (Nominal): This is the motor’s comfortable, continuous power output. It can run at this level all day without overheating.
• 500W (Peak): This is the maximum power the motor can draw for short bursts—think 10-20 seconds. This “peak” power is what you’ll use to get up a steep driveway or accelerate quickly across an intersection.

You’ll also hear the term “Brushless DC (BLDC) Motor.” You don’t need to know the physics, just know this: it’s the modern standard. It’s more reliable, more efficient, and requires virtually zero maintenance compared to older, brushed motor designs. The motor itself, often housed in the center of the rear wheel (a “hub motor”) like on the S14, is a sealed, self-contained unit.

Mentor’s Takeaway: For a compact folding bike, a 350W/500W peak motor is more than enough. It signals that the bike is built for city hills and zippy, stop-and-go commuting, not professional mountain climbing.

2. The Battery: Volts (V), Amp-Hours (Ah), and Watt-Hours (Wh)

This is the single most confusing, yet most important, part of the spec sheet. Let’s use the classic “water” analogy—it’s the easiest way to understand it.

• Voltage (V): Think of this as the water pressure in the hose. Higher voltage (e.g., 48V, 52V) delivers power to the motor more forcefully. 36V is a very common and reliable standard for compact bikes.
• Amp-Hours (Ah): Think of this as the size of the water tank. It’s a measure of the battery’s capacity. A 10Ah battery holds more “fuel” than a 7.8Ah battery.

Now, you can’t just look at one or the other. You have to multiply them to find the real number that matters: Watt-Hours (Wh).

Formula: Voltage (V) x Amp-Hours (Ah) = Watt-Hours (Wh)

Watt-Hours (Wh) is your “gas tank.” This is the single best metric for comparing the total energy (and potential range) of two different e-bikes.

Case Study: The Windone S14
The S14 lists a 36V 7.8Ah battery. Let’s do the math:
36 Volts * 7.8 Amp-Hours = 280.8 Watt-Hours (Wh)

Now we have a concrete number! This 280.8Wh “gas tank” is what gives the bike its range. When you’re shopping, a bike with a 500Wh battery has a significantly larger “tank” than this one—but it will also be much heavier and more expensive. For a lightweight, folding bike, 280-300Wh is a common size, balancing portability with a practical range.

Key Features to Look For: * Removable Battery: As seen in the S14 example, the battery can be unlocked and removed. This is a critical feature for commuters and apartment dwellers. You can park your bike in a lobby or garage and take just the battery inside to charge at your desk or in your kitchen. * BMS (Battery Management System): You won’t see this advertised, but every quality lithium-ion battery has one. This is an onboard computer chip that acts as the battery’s “brain.” It protects the battery from overcharging, over-discharging, and overheating, which is essential for both safety and a long lifespan.

3. The Range: “28-50 Miles” and What It Really Means

You will see a range listed, and it will almost always be wildly optimistic, like “Up to 50 miles.” This is the #1 source of customer disappointment. Let’s clear it up.

You get this range only under two conditions:
1. Pedal Assist (PAS): You are actively pedaling, and the motor is just helping you.
2. Throttle-Only: You are not pedaling at all and using the bike like a small scooter (if it has a throttle).

The “28/50 miles” range listed for the S14 means “up to 28 miles” in one mode and “up to 50 miles” in another. The 50-mile range is only achievable on the lowest pedal-assist setting (PAS 1), on perfectly flat ground, with no wind, by a lightweight rider.

A More Realistic Formula:
A good, conservative rule of thumb for a throttle-only range on flat ground is:
Watt-Hours (Wh) / 20 = Realistic Miles

For our S14 example (280.8 Wh), that would be:
280.8 / 20 = ~14 miles

This means you could likely ride for 14 miles without pedaling at all. When you add your own pedal power (PAS), you mix your human energy with the battery’s energy, which is how the range stretches to the advertised 28 miles or more.

Mentor’s Takeaway: Ignore the “max” range. Look at the Watt-Hours (Wh). A 280.8Wh battery is excellent for a 5-10 mile round-trip commute, with plenty of power to spare.

Beyond the “Big Three”: Specs That Define Feel and Function

Power is only half the story. The bike’s design—its wheels, frame, and components—defines how it feels to ride.

Wheel Size: 14-inch vs. 20-inch vs. 26-inch

For folding bikes, you’ll generally see 14-inch, 16-inch, or 20-inch wheels. * Why small? Smaller wheels, like the 14-inch tires on the S14, make the bike incredibly agile and maneuverable. They are perfect for sharp city turns and, most importantly, they allow the bike to fold into a much smaller package. * What’s the trade-off? Smaller wheels are less stable at high speeds and don’t roll over potholes and bumps as smoothly as larger wheels.

This is why you’ll see another spec: Suspension. To compensate for the bumpier ride of small wheels, many compact bikes, including the S14, add shock absorbers (suspension) to the front fork and even the rear. This gives you back the comfort that the small wheels take away.

The Fold: Weight and Dimensions

The entire point of a bike like this is its portability. * Weight: The S14 is listed at 48.5 lbs. Is this “light”? For a regular bicycle, no. For an electric bike with a motor, battery, and suspension, yes, that’s quite manageable. You won’t want to carry it for a mile, but you can definitely lift it up a flight of stairs or onto a train car. * Folding Mechanism: You want a fold that is fast, intuitive, and secure. The goal is to go from “riding” to “carrying” in under 30 seconds.

The Unsung Hero: Brakes

This is simple. In 2025, do not buy an e-bike that does not have disc brakes.

Traditional rubber “rim brakes” fade in the rain and are not strong enough to stop a heavy e-bike at 19 mph. Mechanical or hydraulic disc brakes (like those on the S14) provide consistent, powerful stopping in all weather conditions. This is a non-negotiable safety feature.

Your Lesson: Putting It All Together

Let’s review what we’ve learned. You are no longer a “no-threshold user.” You are an informed researcher.

When you look at the Windone S14’s product page, you’re no longer seeing a jumble of numbers. You’re seeing a clear story:

“This is a compact folding e-bike designed for urban portability. Its 350W/500W peak motor is strong enough for city hills, and its 280.8Wh removable battery provides a practical range for commuting, especially since I can charge it at my desk. Its 14-inch wheels make it agile and extra-small when folded, and the dual suspension ensures the ride is still comfortable. Finally, its disc brakes mean it’s safe.”

See? You just decoded your first e-bike. Now you have the skills to look at any e-bike, do the math, and understand exactly how it will (or won’t) fit into your life.