BuildMyMTB
Prototype - Evolving Daily

Box Rear Derailleur

1 model, 3 verified variants. Only rows checked against Box’s own page are listed.

A value shown as a set or a range differs between this model’s variants and is never one variant’s spec. A cell marked not stated is a field the maker does not publish, so nothing here checks it.

ModelVariantsSystemSpeedsActuationMaximum cogMountPrice (MSRP)
Box Box3Drivetrain system Box Prime 9 (9-speed)9-speed (rear index count the maker rates it for)Mechanical (cable)Largest cog 50 teethStandard hanger$83.99 to $165.74

Source for every row: Box’s own product pages, last checked between 2026-07-14 and 2026-07-31.

The checker compares the dimensions listed in what we check, and what we don’t. “No conflicts found” means no conflict among those dimensions — not a guarantee that a build works. Errors mean it won’t fit; warnings mean it works but check; infos are notes.

Check a whole mountain bike build in the builder