You don't have to do anything. I remember when I first noticed what you are talking about: I was riding home from work on a Nashiki that I had bought at a garage sale the earlier weekend, and noticed my bikes shadow had a chain that was so slack on the bottom it looked like a sway backed mule. So I pulled over and looked it over, I had already covered 7miles, without a problem, so I rode on home, and read up on it, it is called "Alpine" gearing. It allows more gear range without going to a Triple.