Lim, B-O · Moon, Y-J and Eun, S-D. Analysis on the differences of mechanical efficiency from design characteristics of wheelchair. Korean Journal of Sport Biomechanics Vol. 13, No. 1,pp. 109-119.`2003 Korean Society of Sport Biomechanics proceedings. The purpose of this study was to investigate differences of the mechanical efficiency of the characteristics of the basketball wheelchairs(cambers & size of the handrims). Nine mechanical efficiency on the characteristics of the basketball wheelchairs(cambers 7 size of the handrims). Nine healthy and normal wheelchair basketball players who had no impairments to their upper extremities were volunteered to participate in this study. VO_2 was collected using automatic gas analyzer(vmax29). Gross efficiency, net efficiency and work efficiency were analyzed from the calculated external power output and energy expenditure. The results were followed. First, gross efficiency in the basketball wheelchairs was observed across the range form 4 to 10%. Gross efficiency in this study showed less values than that from the literature reviewed in the arm cranking(15%), racing wheelchair(above 30%), gait(27%) and cycling(18-23%). Second, the small size of handrim(61cm) at the 16 degrees of camber produced higher efficiency values than the large size of handrim(66cm) whereas the different sizes of handrim at the 20 degrees of camber did not show any pattern. Third, both faster speed(1.11㎧→1.39㎧) and increase in treadmill inclination produced increases in energy expenditure. The results of this study may provide not only better understanding of the mechanical efficiency with adequate camber degree and proper size of handrim but also fundamental information for manufacturing the wheelchair.