ABSTRACT
In recent years, the multi-speed bicycles become the main stream on the market. As shown in Figure 1, the chainwheel, freewheel and the chain compose the freewheel-type transmission system of a multi-speed bicycle. The chainwheel and the freewheel respectively includes several chainrings and cogs that contain different numbers of teeth. The front and rear derailleurs guide the chain to engage larger chainrings or cogs, or guide the chain to drop to smaller chainrings or cogs, to produce different gear ratios for a cyclist.
