One other question: With the REAR DERAILER low limit screw. I am trying to figure how to get the best setting without throwing the chain into the spokes. How much leway do you have with loosening the L screw once the chain shifts to the biggest cog? What I am saying is, let's say the chain shifts up to the big cog, how many more turns of that screw will make it jump to the spokes? I just want to know so that when I fine tune, I will not go to far. I have read park and shimano. The problem is the teeth on the cogs are not perfectly straight, so if I line the pulleys up with one tooth on the cog, it may be too far in on some teeth of the biggest cog, just right on others and too far out on others yet......