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Inertia in Flywheel Training

Inertia in Flywheel Training

Understanding the concept of inertia is key to reaping the benefits of flywheel training. Instead of using weights, the resistance in flywheel training is created through the inertia of a flywheel which is rotated with muscle force.

Gravity vs Inertia

Traditional strength training creates resistance by lifting a fixed weight against gravity. Barbells, dumbbells, and weight stack machines all rely on mass and gravity to determine how heavy an exercise feels. Flywheel Training works differently.

In Flywheel Training, resistance is created by accelerating and decelerating a rotating flywheel. Instead of lifting a weight, you apply force to spin the flywheel, and that same energy is returned to you in the opposite direction. The resistance you experience depends on two factors:

1) The inertia of the flywheel
2) How hard and how fast you apply force

This principle is similar to a yo-yo. The faster and harder you pull, the more force you must control on the return.

The kBox, kPulley and SingleExx

Our kBox, kPulley and SingleExx devices can be equipped with two or four flywheels simultaneously depending on the device model. Additionally the Advanced Flywheel Knob can help to boost that capacity by two flywheels of a compatible size. Our flywheels come in five different sizes with inertia ranging from 0.005 kgm² to 0.070 kgm².

  • Extra Large: 0.070 kgm² (only compatible with the kBox Pro, LegExx, LegFlexx and all kPulley devices)
  • Large: 0.050 kgm²
  • Medium: 0.025 kgm²
  • Small: 0.010 kgm²
  • Extra Small: 0.005 kgm²

Choosing Intertia

To make inertia selection easier, Flywheel Training can be divided into Workout Zones. These zones describe the training intent, not a fixed flywheel size.

Warm up and Preparation
Lower inertia, faster movement, focus on rhythm and control

Technique and Skill Development
Moderate inertia, smooth acceleration and deceleration

Power
Faster effort with controlled braking

Strength
Higher inertia, slower movement, higher force output

Overload
High inertia combined with strong drive and controlled deceleration

Training zones depend on how you move, not only on the flywheel you choose.

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