Do You Need 21 Speeds on an E-Bike? The Truth About Drivetrains

You look down at the handlebars of your new electric bike. On the right, you see the 5 levels of your motor’s pedal assist. On the left, you see shifters for 3 gears. And on the right, more shifters for 7 more gears.

You do the math… 3 x 7 = 21 speeds.

A thought bubble pops up: “I have a 750-watt peak motor. Why on earth do I need 21 gears? Isn’t that… obsolete?”

It’s an excellent question. It feels like having a racecar engine in a horse-drawn buggy. But the truth is, those 21 gears are the smartest part of your bike. Using them correctly is the #1 difference between a rookie rider and a pro. It saves your battery, it saves your motor from strain, and it saves your knees.

Here’s why your motor needs those gears, explained with a simple analogy.

Your Motor is a Manual Transmission Car

Think of your e-bike’s hub motor (like the 500W/750W motor on the Funhang EB-M1) as the engine in a manual-transmission car.

What’s the first thing you do when you stop on a steep hill in that car? You shift into first gear.

What would happen if you tried to start in fifth gear? The car would shudder, lurch, and stall. You’d burn the clutch and overheat the engine.

Your e-bike motor feels the exact same way.

When you are at a dead stop at the bottom of a hill, if you are in your hardest mechanical gear (smallest cog in the back) and hit the throttle or PAS 5, you are forcing your motor to do the exact same thing. It has to use a massive, inefficient spike of “peak power” to get you moving, which overheats the motor and devastates your battery.

The Pro Move: Before you stop, shift your mechanical gears to an easy gear (biggest cog in the back). Now, when you start, you and the motor are both in “first gear.” Your light pedal stroke, combined with the motor’s assist, will feel effortless. You’ll be preserving your battery and your motor.

The Problem: “Ghost Pedaling”

Now for the opposite scenario. You’re on a flat, open road. You’re in PAS 5, cruising at 20 mph. You decide you want to “help” by pedaling.

But when you try, your feet are spinning frantically, completely out of control, like a cartoon character. You’re not “connecting” with the road; you’re just flailing.

This is called “Ghost Pedaling.”

It happens because your gear is too easy for that speed. The motor is going faster than your feet can keep up with.

The Pro Move: Shift into a harder mechanical gear (a smaller cog in the back). Suddenly, you’ll feel resistance. You can “catch up” to the motor’s speed. Now you are in sync, adding your own power to the motor’s, and riding with stability and control.

The Real Goal: Finding Your “Cadence”

Those 21 gears aren’t just for “hard” or “easy.” They are for Cadence (pronounced kay-dence).

Cadence is your pedaling rhythm—the speed at which your legs comfortably like to spin, measured in Revolutions Per Minute (RPM). Most people are comfortable at around 70-90 RPM.

Your gears are the tool you use to keep your legs in that happy 70-90 RPM zone, no matter what speed you’re going. * Going slow up a hill? An easy gear lets you spin at 80 RPM. * Going fast on a flat? A hard gear lets you spin at 80 RPM.

Your motor also has a “happy” RPM range where it’s most efficient. Using your gears helps keep both you and the motor in your most efficient, comfortable zone.

A Simple “Hack” for Your 21-Speed Bike

Okay, 21 speeds is a lot. The left shifter (for the 3 big gears up front) can be confusing. Here’s a simple way to start:

1. Look at your left shifter. Put it in “2” (the middle gear).
2. Forget about it.
3. Now, just use your right shifter (the 7 gears in the back).
4. Use “1-3” (easy) for hills and starting.
5. Use “4-5” (medium) for cruising.
6. Use “6-7” (hard) for high speeds.

You’ve just simplified your bike into a 7-speed, which is all you need 90% of the time. You can save those other gears for when you’re an advanced rider.

Conclusion: Your Motor Provides Power, Your Gears Provide Wisdom

Don’t ignore those shifters. They are not obsolete. They are your secret weapon. * Use your motor (PAS 1-5) to decide how much assist you want. * Use your gears (1-21) to decide how fast you want to pedal.

A smart rider on a Funhang EB-M1 will use their easy gears on hills, their hard gears on flats, and will get 10-15 more miles out of their battery than a rookie who leaves it in one gear. Your motor is the power, but your gears are the wisdom. Use them together.