Hello I need a method of locking a freewheel cog at the back wheel of a bicycle. Have motorized bicycle. It has a chain from the engine to an overrun cog on back wheel. The engine will only be used intermittently, about 10% of the time. I need to jump start the engine often, but I need as little effect on the pedaller as possible whilst the engine is not running. Hence the overrun cog at the back wheel rather than a constantly driven chain with a clutch up at the engine. Would anyone know of any simple robust designs, preferably off the shelf.