In addition to its rehabilitation potential, a prosthetic designed for cycling will enable amputees to have the benefits of cardiovascular exercise and participation in sports. A prosthetic design for cycling can be aided by an understanding of the forces involved. Amputees have significantly more pedaling asymmetry than the intact population. Factors creating pedaling asymmetry are: strength imbalance between limbs, difficulty in directing forces effectively with prosthesis, and sound side overcompensation at the top and bottom of the pedal stroke. The stiffness of the prosthetic foot was found to have no effect on asymmetry.