Center of gravity in an active wheelchair: how it affects riding
Moving the rear wheel axle forward brings the center of gravity closer to the wheelchair's point of support, which increases maneuverability but at the same time reduces stability. It is one of the most important settings on an active wheelchair, because it affects how easily it turns, how much effort it takes to propel and the risk of tipping backward, all at once. Understanding this relationship helps you choose a configuration consciously instead of relying only on factory settings.
In the SPARX One configurator, the center of gravity is adjusted continuously, independently of the wheel tilt angle, which on this model is 2 degrees of camber. The two parameters work together, so it is worth understanding exactly what changes in the wheelchair's behavior with each adjustment before you settle on a configuration. Below we explain the mechanics behind both adjustments step by step.
In short
Moving the axle forward - increases maneuverability, but also increases the risk of the wheelchair tipping backward.
2 degrees of camber on SPARX One - improves lateral stability and grip when turning, while keeping the wheelchair compact in width.
Center of gravity adjustment - in the SPARX One configurator it is set continuously, independently of the wheel tilt angle.
Caution for beginners - a more maneuverable, aggressive axle setting is recommended only once you have gained riding experience.
Table of contents
- What does moving the rear wheel axle change?
- Why does a more maneuverable setting increase the risk of tipping backward?
- How does camber affect the center of gravity and the line of travel?
- Who is a more aggressive, maneuverable axle setting for?
- How does the center of gravity affect how easy the wheelchair is to propel?
- How do you adjust the center of gravity in the SPARX One configurator?
What does moving the rear wheel axle change?
Moving the rear wheel axle forward shortens the distance between the user's center of gravity and the wheelchair's point of support, so the wheelchair responds faster to every movement and turns more easily. The same change, however, reduces the stability margin to the rear, because less weight remains behind the pivot axis. Moving the axle backward works the other way round - the wheelchair is more stable and harder to tip, but it loses maneuverability and needs more effort with every turn. That is why the axle position is always a compromise between ease of maneuvering and a sense of safety.
Why does a more maneuverable setting increase the risk of tipping backward?
The closer the rear wheel axle is to the user's center of mass, the smaller the moment of force needed to tip the wheelchair backward, for example when setting off abruptly or riding up a curb. People who are just starting out on an active wheelchair rarely have a feel for this margin yet, so adjustments that increase maneuverability are best introduced gradually rather than going straight to the most aggressive setting. Height-adjustable rear anti-tip wheels can provide additional protection by limiting how far the frame can tip. Their role is greatest precisely while you are learning to ride and with settings that make the wheelchair more maneuverable.
How does camber affect the center of gravity and the line of travel?
Camber, the angle at which the wheels are tilted from vertical, is 2 degrees on SPARX One and works independently of the axle position itself, although together the two parameters shape how the wheelchair behaves in a turn. A slight wheel tilt increases the contact area between the tire and the ground when turning, which improves lateral stability and grip, especially when riding dynamically. At the same time, this setting keeps the whole wheelchair compact in width, because the wheels do not have to be set further apart to achieve a similar stabilizing effect. This solution works particularly well for quick changes of direction, typical of a more active riding style.
Who is a more aggressive, maneuverable axle setting for?
A more maneuverable axle setting works best for riders with plenty of experience and good trunk control, who can consciously compensate for the wheelchair's lower stability with their own posture. In practice, this applies to people who train intensively or have been using a wheelchair for a long time, for whom fast response and minimal effort when turning matter most. This configuration is especially useful in tight spaces, where every centimeter of turning radius counts. With less experience, the gain in maneuverability usually does not make up for the loss of stability margin.
How does the center of gravity affect how easy the wheelchair is to propel?
The closer the user's center of gravity is to the rear wheel axle, the less resistance you have to overcome with every push of the rim, which means less strain on the shoulders and arms on longer rides. A center of gravity set too far back requires more strength when setting off and riding over bumps, because more of the weight then rests on the front casters. This setting is therefore worth treating not only as a question of maneuverability, but also as something that affects comfort and how quickly you tire in everyday use. For this reason, the center of gravity is adjusted individually rather than to one universal setting for everyone.
How do you adjust the center of gravity in the SPARX One configurator?
In the SPARX One configurator, the center of gravity is adjusted continuously, which lets you match the rear wheel axle position to a specific body shape, riding style and level of experience instead of choosing from a few preset variants. This adjustment is made together with setting the frame geometry to the nearest centimeter, so both parameters - the dimensions and the center of gravity - are matched to each other in the same configuration. If you are unsure about the right setting, the SPARX team will help you choose the parameters directly from the configurator. This approach matters especially when you are just starting out and do not yet have a feel for how a change in the axle position will affect handling.
Summary
Moving the axle forward - increases maneuverability at the cost of stability and the safety margin to the rear.
2 degrees of camber - improves grip and lateral stability when turning, while keeping the wheelchair compact in width.
Careful adjustment for beginners - more maneuverable settings are best introduced gradually, ideally with anti-tip wheels.
Individual fit - the center of gravity is adjusted continuously, depending on the user's body shape, riding style and experience.