Rode the initial RASDAK ride - "Faces to the Falls" in June of 2013 and it was great. This year's event has a dual purpose in raising awareness and to help the ranchers who lost thousands of cattle during South Dakota's October Blizzard. Will be starting out in the beautiful Black Hills of South Dakota while also looping through the awesome Badlands.
Did have to sag once on the third day last year from last rest stop at mile 85, ride closed down as there was some road construction on the last leg of our route to Winner, SD. Was the toughest day as it was our warmest with strongest headwind. No one complained, except for one rider who kiddingly wanted a refund because he didn't get his full advertised milage.
That day's ride described in 2013 Rasdak facebook:
John Curry - "My favorite part of the ride was after the long grind into the wind all day and finally making it to the red hills bar in Carter. I got dropped by my group four or five times only to have them check up and let me get back on. Then getting to the bar and sitting in the shade on the porch I went from feeling like a whipped pup to very satisfied in about two beers."
Taking 15 mile sag on Magic Bus because of Road Construction
I can't look at your link (blocked here at work) and I'm not going to be attending said ride anyway, but my wife and I are planning a vacation through SD this September and I'm hoping to be able to get in some rides through some of the state. I was through SD back in '93 and remember it being hilly and very pretty. Maybe I'll try to duplicate some of the ride.
If you happen to be in the western part of the state here are some routes I did on a short trip I did with my son in 2011. The Mickelson trail is awesome and can be ridden with a road bike. Would suggest something wider than 1.25" tire though. Very pretty in late summer and early fall with less traffic on roads. Not as scenic in the eastern part but quite a few less traveled paved roads to choose from. Biggest drawback on our wide open spaces is that it can be hot and windy in mid summer.