In Reply To:
I guess no one really sees how hard it is to ride 45km/h for 4h without drafting even for pro bike riders.
they are maybe a handful of pro riders who could do that...none of the sprinters, none of the climbers. Lance, Jan, Vino, maybe the 'I don't care it's draft legal' pro riders like Durant, Voigt, Piil...but for most the answer is no...
just check the average speed done at the Grand Prix des nations on a course not as hard as Kona, which is pretty much the longer official UCI ITT, and you'll realize that there aren't so many who can do that.
British competition record for 100 mile TT (closest distance to IM bike): 3hr 22min 45sec. At that average speed the IM bike would be 3hr 47. This record was made on a fast course with traffic, but no drafting of other cyclists was needed.