A method and system for resource management is provided. A second communication device is physically coupled to the substrate and has an optical receiver for communicating information. Each hopper section includes a controllable discharge opening that permits precise control of the amount of each concrete color that is discharged from the hopper. The channel comprises an arching portion into which the band at least partly protrudes by arching over the locking member when the locking member engages a rung of the band. Alternatively, the sensor retainer may include a fixing member for mounting a derailleur or other transmission to a bicycle frame and a sensor element mounted to the fixing member.