Karl, RAGBRAI is definitely a thing. The largest organized bike ride, or something like that, in the world. I think the numbers of riders are in the 5 figure region. They went by my house one year and though I was 300 yds from home, it took a half hour to get that last few yards. It was fun to watch however.
If you can do 50 miles a day, you could probably still do it with one longer day. I think they might go as much as 60 miles on one day of the ride but not more than that - I'm not sure though. And the route changes every year. You can always ride just part of it too. Many do that. There was also a major tiff within the organizers last fall, and I don't really know how that will shake out this year.
I've never ridden the RAGBRAI. It's not my kind of deal. I used to race bikes though, esp. back in my Georgia days. Mostly road races with a few criteriums thrown in.
I've had my left knee scoped and cut back in about 2009. This is the right one. Meniscus trimming and some general house cleaning. I think I will be back to running by fall and definitely ready for big game and birds in October. It will be a MUCH better year than last, I hope.