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Custom FrameA Custom frame length is an often misunderstood concept in ultralightweight rigid manual wheelchairs. However, it is a significant factor in how the chair will ultimately perform and feel for your client. The frame length is generally defined as the measurement from the end of the seat sling to the end of the frame.

On an ultralightweight rigid wheelchair, the frame length is standard, set by individual manufacturers, but can be customised based on the user’s needs, comfort, and preference for performance.

Many factors determine which configuration choice is best for your client. Knowing what is standard and how custom modifications deviate both in function and mechanics can help lead the discussion and allow your client to decide what is best for their unique goals and functional abilities.

An important distinction with frame length is that it is NOT the same as seat depth. This is a common misconception and could lead to decreased performance in the chair if not correctly configured. Frame length can potentially affect seat depth and should be considered along with front frame angle to ensure proper performance and manoeuvrability of the chair.

Knowing and understanding how to frame length affects other critical factors in optimum set-up will allow you and your client to choose if a custom frame length is the best solution for their needs.

Key Factors Affected by the Frame Length

Size and Weight

The overall length of the chair will be affected based on custom frame selection, either decreasing or adding, changing how the chair performs. The overall weight of the chair can also be affected, with a longer frame length adding additional weight to the wheelchair, which could make it less functionally compatible for some clients.


Manoeuvrability in an ultralightweight manual wheelchair is probably one of the essential features. Making a chair easier to manoeuvre with optimum set-up includes frame length, whether standard or custom. The client’s functional abilities and goals are the primary considerations in selecting the frame length.

A shorter frame will significantly increase the turning precision of the chair, making it more manoeuvrable, mainly if the chair will be used primarily in a smaller space. A custom frame length in a shortened position is one of the most common selections.


A certain amount of stability is essential, but not at the cost of manoeuvrability. However, a stable chair and a manoeuvrable chair are configured differently, and frame length plays a role. Ensuring the chair is balanced enough for the client to complete all activities without losing stability is critical. For example, reaching to the floor to retrieve a dropped item without losing balance or the chair becoming unstable. Adding additional frame length will make the chair more stable but most likely less manoeuvrable, especially in tighter spaces.

Position within the Chair

Depending on the custom frame length selection of lengthened or shortened, the client’s position will be altered, affecting function, manoeuvrability, and stability. Lower extremity position will be affected, including foot placement and knee angle.

Front Frame Angle

Since the front frame angle does NOT determine the knee angle (because where the client places their feet will determine the knee angle), it WILL determine the wheelchair footprint or the overall length of the chair. Changes in frame length can affect the lower extremity position.

Center of Gravity

Because COG on a wheelchair is measured from the back canes, the position won’t change with frame length changes, as those are made to the front of the chair. However, the manoeuvrability and stability of the chair may change, requiring adjustments to the centre of gravity for optimum performance and function.

Since frame length other than standard is a custom request, discussions and trials with the client should occur before order confirmation to ensure the best fit, function and manoeuvrability.

The best way to ensure proper fit is to set up a demo as closely as possible to determine the client’s dimensions to simulate the outcome best. Motion Composites Southeastern Regional Sales Manager Todd Richardson, ATP, with 25+ years in the industry and as many years as a rigid wheelchair user, shares some insights into fine-tuning frame length on your rigid chair for best performance.

“To begin with, don’t add length “just in case,” this can lead to poor performance, and the chair will feel heavier than it is, and can cause shoulder pain, fatigue, and could lead to an abandonment of the equipment. Also, if the chair is already 18” deep, don’t add additional frame length because the client is tall; it can lead to very poor manoeuvrability and awkwardness in tight spaces. If concerned about length, try adding seat slope. The most common custom frame length requested at Motion Composites is -1.

Understand that ANY changes to the wheelchair configuration will change how the chair feels. ½ Inch of adjustment on the centre of gravity is considered a significant change. It determines whether the chair will perform as an extension of the user, or feel extremely heavy, so realising that adding or subtracting 1-2 inches on frame length WILL make a significant impact on the performance of the chair.”

Each manufacturer has set standard frame lengths. To ensure a proper fit for your client in a Motion Composites Apex Carbon or Apex Aluminium, request a demo from your supplier or reach out to your local Motion Composites representative by clicking here.