The B Series from Crank Brothers are a bit-based tool system with a magnetised socket driver that fits easily into a jersey pocket pockets or hydration pack bag

RAP 6 multi-tool

They include custom-made replaceable stainless steel bearings

Perfect for delicate finishes

Topeak Chain Wear Indicator and Hook Tool PDP|Colour The B Series from CrankEnsure your chain and drivetrain are in good shape! The Topeak Wear Indicator easily tells you whether you need to replace your chain. It also features a hook tool to help install new links. Chain Wear Guide User Instructions: 1) Put " STEP 1 " inside a chain space and fully engage a roller. 2) PRESS " STEP 2 " on a roller. If "STEP 2" can't engage in the roller your chain is good to go. If "STEP 2" can engage in the roller its time for a new chain.