The Carbon Stages Power Meter left arm system features a clever design that is directly compatible (no additional components needed) with unit unique detachable spindles to work with specific right arm crank systems, in this case the SRAM DUB MTB designs. You need the proper Stages Spindle to make the Stages left arm power meter attach to the drive side of the Specialized. Spindle version "G" works only with the SRAM DUB MTB which features a DUB 28.99mm spindle diameter.

The spindles are manufactured for Stages Cycling by Full Speed Ahead, forged and machined out of aluminum. The Stages Power Meter Spindles are specifically designed to meet or exceed the performance of the manufacturer's stock component, while allowing the retrofit of the new carbon left crank Stages Power Meter to a rider's right side crank arm/spider