LB007 Vertical Elliptical
Rotational Kinetic Energy Calculation
This calculation estimates the rotational kinetic energy stored in the LB007 flywheel when the pedal stroke rate is 1 stroke per second and the two-stage transmission ratio is 1:15.
Vertical Elliptical: 5"x11"
Pedal Tilt Range: -1° to 18°
| Drivetrain Data | |
| Crank | 65 mm |
| Coupler | 420 mm |
| Rocker | 224 mm |
| GroundLink | 405 mm |
| CrankWheel | ⌀ 240 mm |
| Pulley S11 | ⌀ 66 mm |
| Pulley S12 | ⌀ 191 mm |
| Pulley S2 | ⌀ 36 mm |
| Flywheel | ⌀ 240 mm |
| Transmission Ratio 1:15 | |
Design Parameters
| Parameter | Value |
|---|---|
| Pedal stroke rate | 1 stroke / second |
| Transmission ratio | 1:15 |
| Flywheel rotational speed | 15 revolutions / second = 900 RPM |
| Flywheel mass | 2.5 kg |
| Flywheel outside diameter | 240 mm |
| Flywheel outside radius | 120 mm = 0.12 m |
Rotational Kinetic Energy Formula
Where:
| Symbol | Meaning |
|---|---|
| KErot | Rotational kinetic energy stored in the flywheel |
| I | Mass moment of inertia of the flywheel |
| ω | Angular velocity in radians per second |
Angular Velocity
With a 1:15 transmission ratio, one pedal stroke per second turns the flywheel 15 revolutions per second.
Estimated Flywheel Moment of Inertia
The flywheel is not a solid cylinder. It has a heavy outer rim, three spokes, and a center hub. Because most of the mass is concentrated near the outside rim, its moment of inertia is higher than a solid disc of the same mass and diameter.
For this estimate, the flywheel mass is approximated as:
| Flywheel Section | Estimated Mass Share | Effective Radius | Estimated Moment of Inertia |
|---|---|---|---|
| Outer rim | 75% | 0.11 m | 0.02269 kg·m2 |
| Three spokes | 15% | 0.075 m | 0.00211 kg·m2 |
| Center hub | 10% | 0.03 m | 0.00023 kg·m2 |
Estimated Rotational Kinetic Energy
Estimated KErot ≈ 111 joules
Interpretation
At a pedal stroke rate of 1 stroke per second with a 1:15 transmission ratio, the 2.5 kg LB007 flywheel is estimated to store approximately 111 joules of rotational kinetic energy.
This stored rotational energy helps the drivetrain maintain continuous motion between pedal force inputs. In an elliptical machine, this contributes to smoother force transfer, steadier resistance, and a more continuous low-impact exercise feel.