i tried to do a search for any ironman prediction websites, but unlike marathon time prediction websites, there aren’t any. can i do a sub 11 hour ironman based on a 5 hour half? i’d be happy with that time goal.
are there any tested formulas for predicting a full, based on a half-ironman time?
thanks,
cyclisto
HIM x 2 +/- 60 minutes…I’d say 11 hours is a good goal.
I’d be cautious about having time goals for a first IM - just focus on completing the race. I think there is a formula in the triathlete’s training bible, but I don’t think it works that well. I did 4:57 and 5:05 at flat 1/2 IM’s in successive years that translated to 12:20 and 11:40 full IM’s (IMLP, Austria) those 2 years.
There are several others, but here are couple of threads of interest.
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By that formula 9 hours would also be a good goal 
Seriously though, 10:45 or 11 is a good goal based on that 5 hour time, if the courses and conditions are similar. If you were loafing a bit on the half and/or have EXCELLENT endurance, you could get nearer to 10:30. Good luck!!!
depends on course, weather, nutrition, pacing, etc. on race day, and how well you train for the IM in the mean time. if you did a hilly 1/2, and are comparing the course difficulty fairly by doing a flat or hilly IM, then yes, it is possible. if you did a flat 1/2 IM like Eagleman, and are doing LP for instance, it will be close!
most people say double your half and give yourself another 30 minutes, but that is not always true. for example, my first real half was Wildlfower, I went 6 flat. did IMC 5 months later in 11:54. so it is possible to go faster than your half time IF you are prepared and do most things “right” on race day.
that said, if this is your first, just be happy with the result.
lol true. i noticed that just after I hit reply but didnt feel like editing it. Oh well
thanks all! out of curiosity, what did tom do at steelhead?
and forget that triathlon prediction site, since i don’t even know are care to know wtf a watt is! 
I’ve done 4:57 for a half. With nutritional failure and a really bad run I did 11:33 at LP. I felt I should have done 11:00 and think that’s a reasonable goal.
(too bad should of doesn’t count.)
HIM time X 2 + 20% = IM time
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most people say double your half and give yourself another 30 minutes, but that is not always true. for example, my first real half was Wildlfower, I went 6 flat. did IMC 5 months later in 11:54. so it is possible to go faster than your half time IF you are prepared and do most things “right” on race day.
Maybe, but a 6 hour Wildflower is like a 5:30-5:40 on a normal course.
It seems entirely plausible that for some athletes they could expect to simply double their HIM time. Depending on how you race, you are likely to never exceed your LT. It becomes simply a question of glycogen storage/utilization.
IF (big IF) your training volume is sufficient for the race, and your fueling is adequate the same pace would be possible.
Now that’s obviously not what usually happens, hence the additional factor in the formula. You need a goal for your IM…because that goal determines your pacing (unless you pace by heartrate). So I’d take the 2 x HIM + 30 minutes formula as your goal and during the last part of the bike and on in to the run you can pick up the pace if you are feeling great.
I did 5and some change and under 5 and then went 10 and some change first IM I did. Wasn’t shooting for a time just figured these were all my first triathlons so just went for a finish at IM Wisconsin and dropped in the 10 and some change…
So, yep its possible to hit 11 or under …
yes, a 6 hour Wildflower is like sticking a fork in my eye, repeatedly, too :).
yes. i agree. WF does not translate into “normal” 1/2 IM times. definitely 20-30 or MORE minutes slower than my half times at Pac Crest (yet another hilly beeyatch). at the time, i was stupid and didn’t know any better. it’s also ridiculously early on the calendar for us Idahoans. i also thought Canada would be monstrously hilly like WF. again. i had no clue. but to be honest, WF scared me silly, so it was a good kick in the butt for IM training.
I think it depends on the courses you pick and conditions on that day.
My first IM in LP was preceded by two halfs that brought me in at 5:35 at the brutally hot and humid Musselman and 4:59 and the pancake flat super fast Esprit in Montreal. My time in LP was 11:25
Last year I did IMFL in 10:28 and that was preceded by a 5:06 in Musselman but the swim was about 6 minutes off and I did the sprint the day before.
That being said it is great to have a time goal but you cannot predict what will happen on race day. Although I dropped almost an hour with my IMFL time my LP race went so much better.
Just for fun… 125 people did florida ironman and 70.3 last year. (edited for slight error on axis
have you actually done a 5 hour half?
12:5x if you drink TOO MUCH on a 95 degree day in Louisville.