The Importance of Center of Gravity

You might be wondering, What’s all the fuss about center of gravity (CoG)?

According to Jeff Adams, president/CEO of Icon Wheelchairs, many clinicians are starting to realize how critical the fit of the chair is, especially adjustments such as CoG, seat angle and back angle.

“Examining the center of gravity position helps illustrate how the configuration can also be much more important than the overall weight of the chair,” Adams says. “It’s well understood in the industry that the goal when setting the center of gravity is to try to keep the loaded weight of the front of the chair as light as possible, while maintaining a usable center of gravity — in other words, we want the chair to be as tippy as possible, as long as it’s safe. Everyone who is familiar with manual chair setup knows that when the center of gravity is too far forward (meaning that more weight that is being carried by the front wheels) the chair loses maneuverability.

“Imagine a scenario where a rider with a theoretical ideal center of gravity setting of 3" (rearward) from the center of the rear axle to the front of the back tube is asked to choose between two chairs, one that weighs 15 lbs. and one that weighs 5 lbs. more. The heavier chair is set up to be idealized for maneuverability, with the center of gravity set at 3", and the lighter chair set at only 2". The 1" difference in the setting will make the lighter chair more difficult to steer and will cause strain on hands, elbows and shoulders.”

Ultimately, a properly configured chair trumps a lighter chair that’s not set up correctly every time.

This article originally appeared in the Seating & Position Handbook 2014-2015 issue of Mobility Management.

Rolling Dynamics, Rolling Resistance &  Optimizing Wheeled Prosthetics