Falls Area Bicyclists Ride and Dine (FABRAD) had a 50K and a 100K route. Below is the map and profile for the 100K route. It was a great ride with a few challenging hills. The ride takes you across the Big Sioux River and through some rolling hills to Inwood, IA. From there it was down hill to the river and to Canton and north to Sioux Falls. It was a great route and I highly suggest it if you are in the area.
I'll try to update this in the near future with road names to make it easier to navigate.