SRAM's X7 3x9 Front Derailleur is made of forged aluminum with a chrome-plated steel cage for strength and precision. The X7 is stiff, giving you reliable shifting season after season.
SRAM precisely paired the different-sized chainrings and redesigned where and how the chain engages with the rings. By aligning the chainring pick-up rivets to the chain pivot pin—rather than the middle of the chain link—you get double the shift opportunities.
Bottom-pull derailleurs are used when the cable is routed underneath the bottom bracket and up through the cable clamp. Top-pull derailleurs work with frames where the cables are routed down from the top tube.
Your seat-tube diameter determines the needed derailleur clamp size.