This index spring sits inside Campagnolo Ergopower shifters and controls the indexing mechanism that positions the derailleur at each gear. When the spring loses tension or breaks, you get ghost shifts where the derailleur moves out of position under load, or the shifter refuses to hold its selected gear. The spring wears from repeated compression cycles during shifts—each click compresses and releases the spring, and after thousands of shifts the metal fatigues and stops returning to its original shape.

Each right-side shifter uses two of these springs, and they work together to maintain consistent indexing across the gear range. The right-side spring geometry differs from the left-side version, so you need the correct spring for the shifter you're rebuilding. This spring fits nine-speed and ten-speed Ultra Shift Ergopower levers from Record, Chorus, Centaur, Veloce, and Mirage groupsets. It does not fit Escape mechanism levers, which use a different internal design.

Replacing worn index springs brings back the crisp, positive shifting you had when the levers were new. The rebuild process requires disassembling the shifter body, removing the old springs, installing fresh ones, and reassembling everything in the correct sequence. Campagnolo and others have published video guides that walk through the steps, though you need patience and careful attention to spring orientation during installation.