Oh, I dunno, the double I did was pretty straightforward and almost painless - and had I not been riding somebody else's bike & saddle (I didn't have a bike that weighed less than 35 pounds) I think it would have been totally painless. Just like a century, you keep on riding. Since it was just two of us and I was in a bit better shape than my riding buddy, *and* we had a tailwind home, it was pretty much just a fun ride. A few hills... lots of cornfields. (It was the Coal City Century, which I'd recommend for a first-timer long distance, tho' since it's the only one I've done...well-stocked, well-placed rest stops, well marked routes and great weather ) It helps to be underemployed sometimes
I'm thinking of doing my own next weekend, which will be harder 'cause I won't be able to draft. It won't compare at **all** to the rides y''all are talking about... I'm in awe