Assessment of Wheelchair Drag Resistance Using a Coasting Deceleration Technique

Hoffman MD, Millet GY, Hoch AZ, Candau RB: Assessment of wheelchair drag resistance using a coasting deceleration technique. Am J Phys Med Rehabil 2003;82:880–889. Objective To apply a recently developed coasting deceleration method to measure rolling and aerodynamic resistances opposing wheelchair propulsion on a variety of different wheelchairs and wheel combinations and on two different ground surfaces. Design For each condition, 20–25 trials were performed across a speed range of approximately 70–300 m/min. The least-squares method was then used to arrive at values for the coefficient of rolling resistance (CR) and effective frontal area of the wheelchair and occupant. Results Wheelchair rolling resistance was found to be velocity dependent under some circumstances. CR values on linoleum differed among folding lightweight wheelchairs and when compared with a rigid ultralight and racing wheelchair. Changing rear wheels and tires on one wheelchair resulted in a 14% difference in CR. Carpet increased CR values by an average of 0.0118 over the values determined on linoleum. As expected, effective frontal area of the wheelchair and occupant values were lower for the racer than for the folding lightweight wheelchair. Conclusions Wheelchair rolling resistance is not always independent of velocity, and CR on linoleum can vary among wheelchairs by as much as seven-fold, and carpet can more than double CR.