Just remember that what goes up, must come down. You’ll be riding river to river. What that means to you is river valleys on both sides of the state. Northern Iowa is table top smooth. The farther south you go, the hillier it gets. Expect tons of rollers.
Unlike other rides that avoid civilization like the plague, Ragbrai goes from town to town so you can explore and enjoy what they have to offer. Don’t think of this as a long ride. It’s more a series of short rides (normally about 10 miles between stops). Never expect to go more than 3 miles without seeing something to drink and probably eat. The biggest rookie mistake is riding too fast.