Three Prime 9 X-Wide Rear Derailleur - 9-Speed Long Cage

What Our Gearhead® Experts Are Saying:

"For riders wanting a simple drivetrain that still handles big-range cassettes, the Box Three Prime 9 X-Wide hits the sweet spot. The clutch keeps things tight over chatter, and the overall build feels solid without adding bulk. It’s a reliable choice if you want fewer gears, easier tuning, and consistent shifting across rough terrain."

The Box Three Prime 9 X-Wide Rear Derailleur is built around the Prime 9 concept: a wide-range drivetrain that uses fewer gears to achieve smoother operation, easier setup, and improved durability. A limited slip clutch stabilizes the chain through rugged terrain, while sealed bearing pulleys reduce friction and extend life in muddy or dusty conditions. The derailleur’s steel-focused construction emphasizes reliability, making it well suited for riders who value long-term performance over shaving grams.

With compatibility across 11–46T and 11–50T cassettes, the X-Wide variant accommodates a broad range of terrain and rider needs. Optimized shift ramps and consistent gear jumps help maintain cadence, and the simpler nine-speed platform aids in maintenance and field repairs. Designed for modern trail riding but grounded in a serviceable, straightforward design ethos, the Prime 9 system delivers predictable shifting and dependable performance ride after ride.