Box Three Prime9 Rear Derailleur, 9 Speed, X-Wide Cage (For 11-50T Cassette), Black

Availability: In stock (1)

The Box Three Rear Derailleur simplifies the features found on the Prime 9 Box One and Two rear derailleurs making for a fully featured wallet friendly rear derailleur. Including a Limited Slip Clutch, Sealed bearing pulleys and a solid construction Box Three Rear derailleurs are compatible with 11-46 and 11-50t derailleurs making it one of the most versatile derailleur offerings for Prime 9.

  • Our Best All-Rounder Derailleur
  • Limited Slip Clutch™
  • Bearing Pulleys
  • Nylon Composite Knuckle
  • Direct Channel Cable Stay
  • Die Cast Linkages
  • Stamped Inner and Outer Cage
  • Prime 9 Technology™
  • Compatible with Standard Derailleur Hangers (Non Direct-Mount)
  • Prime 9™ Drivetrain Compatibility Manual
  • Why Prime 9?
  • Box One Prime 9 11-50T Cassette Black
  • Box Two Prime 9 11-50T Cassette Black
  • Box Three Prime 9 Cassette Black
  • Box One Prime 9 Chain 126L DLC Black
  • Box Two Prime 9 126 Link Chain Nickel
  • Box Three Prime 9 126 Link Chain Polished
  • Box One Prime 9 Shifter Black
  • Box Two Prime 9 Shifter Black
  • Box Three Prime 9 Shifter Black

No, Shimano direct mount hangers are proprietary and are not compatible with Box derailleurs.

No, traditional 9 speed systems use a Cable Pull that is not compatible with Prime 9.

No, Box Prime 9 derailleurs are not currently compatible with drop bar shifters, but we do offer a clamp for our shifters to mount on some 31.8mm drop handle bars.

We suggest removing the derailleur from the bike and using a soft bristle brush or rag with soapy water or a mild de-greaser. We do not recommend pressure washing, strong solvents or de-greasers as they could degrade the surface coating.

Please see our installation video at

Material Aluminum, Glass Fiber / Nylon Composite, Steel
Finish Matte Black
Weight 349g/12.3oz
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