28mph? Were you on a Ducati Scrambler?
That speed would translate to a 53:30 40k TT, which was the standard distance when I was doing things intentionally that made me puke on a bike. That would have been a pretty solid time (top 5-10) for a pro/1/2 race.
Current distance is 32.3k (20.1 miles) which would have given you a time of 43 mins and small change. Current USA champ is an Ineos Gren pro with a time of 39:03. So I say puke it out and call yourself a BEAST.
it is 17.4 mph.