SRAM

S100 Eagle Rear Derailleur - 12-Speed, Traditional or UDH Half Mount Capable, 50t Max, B1

SRAM S100 Eagle Rear Derailleur is a 12-speed mountain bike rear derailleur built around a decade of Eagle drivetrain development, with an updated bushing fitment process aimed at long-term durability and consistent shift accuracy. With support for a 50T max cog and full 500% range compatibility, it’s a practical choice for riders who want reliable performance across steep climbs, high-torque efforts, and mixed conditions—without giving up serviceability or broad parts compatibility.

• 12-speed Eagle compatibility - Works with the SRAM Eagle ecosystem and is backward compatible with SX, NX, GX, X01, and XX1 for straightforward repairs and upgrades
• Traditional or UDH Half Mount capable - Mounts to a standard derailleur hanger, or can be configured for UDH + Half Mount plate for increased hanger interface security (UDH and plate required separately)
• 50T max / 500% range support - Designed to pair with 10-50T or 11-50T Eagle cassettes for wide-range gearing on modern MTB setups
• Drag Spring cage damper - Helps control cage movement for more confident chain retention on rough trails and under hard pedaling
• X-Actuation - Matches Eagle drivetrain shifter actuation for consistent indexing and predictable shifting feel
• Compatibility note - Not compatible with Eagle 70, Eagle 90, or Eagle Transmission systems