||Benefits of single-leg cycling may be compromised because single- and double-leg cycling are biomechanically different. Specifically, during normal double-leg (2L) cycling the gravitational forces acting on each leg are essentially balanced by the contralateral limb and thus do not require active leg flexion. Conversely, single-leg (SL) cycling requires active leg flexion. Recently, The Neuromuscular Function Laboratory at the University of Utah devised a counterweighted cycling crank that facilitates SL cycling with similar biomechanics to normal 2L cycling. The purpose of this study was to evaluate SL noncounterweighted pedal powers (SL-0), SL counterweighted pedal powers at 20 and 30 pounds (SL-20 & SL-30), and compare to normal 2L cycling. Eleven trained cyclists (age: 39 ± 7 years, mass: 172 ± 42 pounds, height: 68 ± 3.5 inches) performed SL cycling with their right leg and 2L cycling with both legs. Pedal powers were calculated during each trial using a force measuring pedal and instrumental spatial linkage system. Participants warmed up for 5 minutes and then performed 6 randomized cycling trials while maintaining 90 rpm at 200 watts 2L, and 100 watts SL-0, SL-20, and SL-30. One-way within-subjects ANOVAs indicated significant effects for cycling condition for both extension [F(1,62) = 26.17, p < .01., partial ?2 = .72] and flexion [F(1,73) = 50.68, p < .01., partial ?2 = .835]. Follow-up pairwise comparisons indicated that 2L cycling generated the most power, 2L-0 the least, with SL-20 & SL-30 falling in between the two extremes, but still significantly different from the low and the high. Within-subjects ANOVAs were conducted using mean-adjusted body weight as a covariate still showed significant differences for power generated under different cycling conditions; also a significant interaction between cycling condition and body weight was observed. The magnitude of power decreased significantly when comparing SL-0 to 2L. However, adding counterweight (SL-20, SL-30) demonstrates evidence that counterweighted cycling brings pedal powers closer to 2L cycling in a SL cycling model. In conclusion, 2L cycling is not the same biomechanical task as SL-0 cycling. Counterweighted single-leg cycling produces similar pedal power to 2L cycling, but the exact application of the counterweight needs further investigation. Properly counterweighted SL cycling may be a beneficial training and rehabilitation modality.