While I won't say that that's untrue, anyone that puts that time down on a solo 100 mile ride is a top caliber professional rider, and one who likely would have won multiple "Grand Tours," especially if he was in the racing scene and would have had at least some exposure. I dunno, maybe it was a one of those super tailwind days in a great plains state...but it's mighty hard to believe.

Just to put it into perspective: Eddy Merckx's hour record was at 7,550 feet, indoors, in ideal conditions and he went 30.72mph for just one hour. (I choose Eddy because he rode on a standard road bike, not a tri or in "superman" position)

This guy did 26.67mph for 3 hours and 45 minutes, presumably outdoors, much closer to sea level (ie, much more wind resistance)

So without getting into the nitty-gritty, this guy put out almost the exact same effort, for 3.75 times as long.