Lever the power out, and the ratio of output to input force is given by the ratio of the distances from the fulcrum to the points of application of these forces. This is known as the "law of the lever." The mechanical advantage of a lever can be determined by considering the balance of moments or torque, "T", about the fulcrum. where F is the input force to the lever and F is the output force. The distances "a" and "b" are the perpendicular distances between the forces and the fulcrum. Since the moments of torque must be balanced, formula_3 .
Shimano Total Integration lever applying tension to the gear cable, the smaller one incrementally releasing it. The Rapidfire mechanism was subsequently adapted to be used in STI levers. In 1990, Shimano introduced their STI shifting levers for road bicycles, which completely integrated the brake lever and shifter. It also redesigned the brake "hoods" where riders commonly rest their hands. This new design worked like a normal brake lever in the longtitudinal plane, but also allowed the rider to shift to a larger cog by pushing the lever so that it pivots laterally. Behind the brake lever, there is a smaller lever that shifts