First, Westside Cycling in Denver, Co is going out of business and will close their doors Feb. 14th or 15th. If your interested its located near Wadsworth and Colfax across from Walmart. They have a few whole bikes on sale and all accessories are half off. They have a lot of stems, front and rear derailleurs(new and used), gloves, some tools, shifters, and other items. I picked up a chain whip and a used rear derailleur today.
Second, the question. The rear derailluer I bought was purchased for parts. The part I Needed was the lower Pulley/cog as mine broke. Now replacing it is straightforward it just has one screw that you pull out. But my question is this, do these pulley/cogs break frequently or its it unusual And to add to this can you purchase these pulley/cogs by themselves?