I just dropped off my bike for a tune-up and the mechanic indicated that my middle chainring probably only had about 1000 miles left. That would be only 2200 miles on the ring. First off, I thought that was low, considering that I lube my chain every other ride and clean my chain every other week. But that's not the point of the post.
Since I'm going to have to replace it soon, I was wondering what I need to determine to see if I can change the ring from a 42T to a 39T. Currently I have an FSA crankset and DA 9'spd deralliers (sp). I want to switch to the 39T because I'd like to get the feel for what its like to ride a double. The small ring is a 30T and the large ring is a 52T. So, what do I need to look at to figure this out? Or, is this even an option?