At the present time I have a 12-tooth up front and a 45-tooth in back. The chain is stock and the axle is about as far to the front as it will go. I just finished reading a post, though, where the author stated that by using a 112 link chain (with a 12/47) the axle moved almost all of the way to the back resulting in a longer wheelbase and better handling on hills. I didn't realize that axle location was that important. Anyway, I guess I now have the answer to my own question: for a 12/47 combination, either a 110 link (axle closer to the front) or a 112 link (axle closer to the rear) will work.