Doubling or tripling the distances(or more) of the original Ironman makes it a totally different event.

It just means you slow down and go further. Once again you begin to deal with competitions that involve physical stress under sleep-deprived conditions which automatically make it an event totally different from the Ironman Triathlon. Also, similar to eco-challenges just because you can do 5 X the Ironman distance, doesn't automatically mean you will be overly successful in the Ironman Triathlon. Some athletes excel at long, slow distance because of their physical make-up,(more slow-twitch fibres) but the tendency to speed up as soon as a shorter race is attempted will change the end result substantially.

Its kind of like if you can run a 35 minute 10 km race and then you enter a marathon. Well of course, you are not going to run the marathon at your 35 minute 10km. pace. You would probably begin walking about mile 14. Also, because you can run a marathon, doesn't mean you will be a better and faster 10 km. runner. They are two totally different events. It follows as well, that if you do an Ironman, you don't automatically become a better marathoner. The marathon is an amazing endurance event in its own right and is totally different from the Ironman.

More by accident than good planning, the friends who conceived the Ironman triathlon, came up with distances that were extremely physically demanding when done sequentially, but yet in the realm of possibility for individuals with a wide range of athletic ability.

Therein lies the secret and the mystique of the Ironman Triathlon. It is an event for everyone. People witness this race and watch ordinary, everyday people striving for the finish line and say to themselves...."I can do this!" They are indeed, at that moment, "Ironstruck."