Presenting a New Simple Accessory for Maximum Inertia

From now on our users can benefit from a wider range of inertia with the help of a new simple accessory. Our CEO Fredrik Correa explains how it works and how you could benefit from it in your training.

We are always thrilled about learning how all the diverse members of the #ExxentricFam implement flywheel training within their training routines. While most users often don’t approach the maximum 0.280 kgm² inertia level offered by the kBox4 Pro, we noticed a group of athletes that regularly trained at high inertia levels with room to even take it up a notch or two. So in true Exxentric fashion, we decided to go back to the lab and develop a solution that would allow everyone to train at their maximum capacity.

After rigorous experimenting and tinkering with the design we’re finally happy to make the  Advanced Flywheel Knob public. This compact item allows you to mount two more flywheels on any kBox4 or kPulley2 device but we generally recommend using it with the kBox4 Pro or kBox4 Lite due to the already high inertia capacity on these platforms (0.280 kgm² and 0.200 kgm² respectively).

Advanced Flywheel knob

When it comes to powerlifting, for example, the Advanced Flywheel Knob will allow you to produce higher forces in your main lifts. With higher inertia and maximal output you can work on building your strength without worrying about any sticking points. The extra inertia will also increase your push-off strength in the deadlift. This will be caused by a longer and tougher eccentric phase in your lifts and a heavier transition from eccentric to concentric.


Moreover you can safely train around injuries or rehabilitate from them, while still maintaining the same or equivalent quality and intensity in your workouts. This can potentially help you to return from an injury even stronger than before. When it comes to rehab, higher inertia is also beneficial in slowing down your movements and in turn making them more controlled.  This allows for easy implementation of HSRT (heavy slow resistance training) for treating tendinopathies.  

If you’re more dependent on generating force over a shorter period of time (i.e. quick jumps) you likely don’t need to use many heavy flywheels in your training simultaneously. Although even if you don’t use the Advanced Flywheel Knob you may still benefit from high inertia levels, which can better prepare you for the large eccentric forces we see in landing, change of direction and vertical forces during sprints. For a more in-depth discussion about how many flywheels you should use in your workouts, please read our earlier blog post here.

If you want to enhance your flywheel training with the Advanced Flywheel Knob we would recommend also considering the following items as additions to your tool box:

  • One or two extra flywheels
    • Size L or XL depending on the equipment you have.
  • Harness
    • For maximal power development in squat variations.
  • kBar
    • Lightweight and durable design for intense deadlift variations.
  • kMeter (for kBox4 Active owners)
    • Provides real time and historical feedback to help program your training and achieve better results.
  • Large Pulley Block (for kBox4 Active owners)
    •  This Pulley Block is more robust, which would allow it to better sustain the potentially larger amounts of energy in the rotating flywheels.

My prediction is that we will see more users realising they can benefit from using wider ranges of inertia in training for strength, performance and in rehabilitation. If you want to understand better how more inertia can help you or which other tools you might need to reach you goals, we are always here to assist.

Exxentric CEO Fredrik Correa

Happy DOMS!

/Fredrik Correa, M.D., CEO



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