What is the Best Flywheel Weight for a Spin Bike and How to Choose the BEST One

If you’re in the market for spin bikes, you might have noticed that flywheel weight is always included in the product specs. Some bikes feature as little as an 8-pound flywheel, while others feature 20 plus-pound flywheels.

As a beginner, you might ask yourself: what is the best flywheel weight for a spin bike?

Fortunately, this is just the question we’re here to address.

In this guide, we’ll also address these related questions:

  • What does a flywheel on a spin bike do;
  • Does flywheel weight matter;
  • Will a light or heavy flywheel burn more calories; and
  • What is the difference between a heavy and light flywheel?

Keep reading to find out!

What is the Best Flywheel Weight for a Spin Bike

Getting to know the spin bike flywheel

Just to make sure we’re all on the same page here – the spin bike flywheel refers to the round disc-shaped wheel that turns as you pedal. It is located at the front of most spin bikes, although now some spin bikes have a rear flywheel and a dual-flywheel system in very rare cases. 

In its most straightforward function, the flywheel helps provide resistance and feel to the spin bike. By feel, we mean how smooth or fluid the pedal motion is. It’s important to note that spin bikes are designed to imitate the feel of riding outdoor bikes, thus providing a natural smooth ride.

On a road bike, you have to push hard, so the rear tire spins, and when you get it spinning, it will continue to turn on its own when you stop pedalling.


What is the Best Flywheel Weight for a Spin Bike

This is the experience that the spin bike flywheel provides for you. It imitates the feeling of riding on flat roads or riding uphill, which means the feel is significantly natural.

To alter the difficulty when pedalling, most spin bikes use magnetic resistance systems, while some use friction brakes. 

There’s a good reason why many prefer magnetic resistance systems – they’re smoother and require less maintenance (the magnets near the flywheel don’t touch to create resistance). On the other hand, friction brakes use brake pads that touch the spinning flywheel to create resistance. 

Whether the spin bike uses a magnetic resistance system or friction brakes, it’s mainly the spin bike flywheel that provides the resistance you work against and creates a smoother pedal motion. And this is true regardless of the flywheel weight.

Does flywheel weight matter?

So, you may find yourself asking, does flywheel weight matter? And, what is the best flywheel weight for a spin bike?

The answer is a resounding yes! Remember your physics class? Your teacher must have taught you the principle that more force and power must be exerted to get a heavier object moving. 

The same principle applies to the flywheel. The heavier the flywheel is, the more force and power needs to be exerted to get the bike spinning. 

We’ll go into detail about heavy and light flywheels below and help you decide what is the best flywheel weight for a spin bike for your needs.

What is the Best Flywheel Weight for a Spin Bike: Heavy vs Light

Heavy Flywheels

Most spin bikes incorporate heavy flywheels to increase momentum. As mentioned, a heavier flywheel takes more energy to get moving, but once it’s moving, it keeps on spinning longer. This is similar to riding a road bike – you have to pedal harder to get it rotating, but it gets easier to pedal once it’s spinning.

But going with the heaviest spin bike flywheel doesn’t necessarily equate to the smoothest ride. This is because eventually, you’ll reach a certain point where the flywheel is too heavy to get it spinning in the first place.

Indoor cycling enthusiasts consider an exercise bike flywheel weight of over 20 pounds (9 kg) to be heavy enough to generate a good amount of momentum as you pedal. That said, most high-quality cycle bikes on the market come out with 40-50 (18-22 kg) pound flywheels, which helps keep the bike’s pedals moving seamlessly.

Yet, when a 20+ pound-flywheel gets spinning, you’ll have a hard time slowing it down, too. This is something you need to consider, especially when you’re recovering from overuse-related pain or injuries on your knees.

What is the Best Flywheel Weight for a Spin Bike

Light Flywheels

Light flywheels are somewhat associated with a rougher ride in the past. There are instances when the flywheel is too lightweight, resulting in a jerky ride and uneven pedal strokes. Of course, uneven pedal strokes can damage your joints. 

But what draws people to spin bikes with light flywheels?

Well, light flywheels require less effort to get started, making the spin bike ideal for beginner riders. Light flywheels also make stopping the bike easier, which means they’re easy on your joints.

The drawback, however, is that light flywheels might not replicate the feel of riding outdoors as much as heavy flywheels do. 

Although some spin bike brands successfully developed a light flywheel system to give a comfortable riding experience, it all depends on how fast or slow the flywheel is spinning.

For example, the Keiser M3i only has an 8-pound (3 kg) flywheel located at the bike’s reverse. Despite its light flywheel system, it still produces a fluid, natural ride, and this is something to do with its unique gear ratio range that provides a faster turning speed. While an 8-pound flywheel that gets the bike spinning really fast sounds very clever, the Keiser M3i, unfortunately, does come at a cost.

Will a light or heavy flywheel burn more calories?

We mentioned earlier that a heavy flywheel takes more force and power to get it spinning, but that experience has little to do with the number of calories burned during your workout.

You’ll mainly apply the most force and power maintaining a set speed with applied resistance. You’ll then burn more calories when there’s more resistance forced on the bike’s flywheel.

But remember this: exercise bikes have different kinds of resistance – brake-based systems resistance, direct contact resistance, magnetic resistance, and fan-based resistance. These types of resistance all function and affect your workout experience differently, so it’s only right to choose the resistance that best suits your goals.

Final Verdict

So, what is the best flywheel weight for a spin bike? There’s no straightforward answer to that question, as it all boils down to personal needs.

If you’re on a budget, an exercise bike with at least a 20-pound (9 kg) flywheel is the way to go. This is often less expensive than its counterpart and ensures faster cycling, smooth-riding operation, enough inertia, and a comfortable ride. In other words, a large flywheel is a good option if you’re looking for a studio cycling experience.

But if you can splurge, a light exercise bike flywheel weight like the Keiser M3I could well be for you. This advanced light flywheel exercise bike comes with gear ratios in the 1:10-1:11 range, meaning the flywheel spins ten or eleven times for every complete pedal rotation. More importantly, a light flywheel is easier on the joints and is perfect for anyone that’s ready to jump into action!

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