Crank Brothers B17 Multi Tool. The Crank Brothers B17 is an ingenious take on the compact multi tool essential for road sidetrail side repairs. The B17 is a 17 bit tool system that includes a selection of common hex bits, Torx bits, screwdrivers, spoke wrenches, as well as a chain tool. When a tool is needed you insert the bit into the magnetized socket driver built into the body to provide stability and leverage. When the maintenance task is complete simply pop the bit out of the driver and insert back into its storage location on the B17. Compact and lightweight, don't leave home without it!