A rear frame for a bicycle is disclosed to include two tubes and a connecting portion. The multi-layer core consists of a small, hard center enclosed by a soft intermediate core layer and an outer core layer. The bed components can be constructed of a metal or a polymeric material. When the CAD program needs to reevaluate a model due to changes, the CAD program calls a callback that results from the registration of the EAP with the CAD program. One or more methods of operating a memory cell include charging a capacitor coupled to the memory cell to a particular voltage level and programming the memory cell from a first state to a second state by controlling discharge of the capacitor through a resistive switching element of the memory cell.