In 1938, Simplex released the first cable-based bicycle gearshifts. Riders would move a lever near the front of the frame that tugged a metal cable attached to a chain derailleur. The shifts were often imprecise and, as debris collected on the cables, moving the levers could become difficult. Nonetheless, bicycle shifting remained cable-driven until 2008, when Shimano introduced the first electronic shifters. The company swapped mechanical derailleurs for motorized ones, cable for electrical wire, and levers for buttons. Last fall, Shimano launched Ultegra Di2, a version of the system that can be retrofit onto most road bikes.