I was curious how much slower you can expect your pace to be while running a half marathon at the end of a HIM Tri. vs. just running a stand alone half marathon. Assume that the course is of similiar difficulty and your properly trained for the events. Thanks for any imput!
My Half Marathon (stand-alone) = 7:27 pace at last PR
First HIM Run Pace = 8:40 in the blazing 90-degree no shade run around The Rez
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As you said assmuming similiar courses, properly trained and PACED for each event. The delta should be 5-10 mins.
I’ll be even more stingy w/ my guesstimate:
3-8 minutes. Or call it :15-:35/mile if you will.
Ale Martinez did up a sweet chart for IM and HIM run splits vs. V.DOT/open half mary splits.
I’m too lazy to do a search right now, but it is the basis of my post, I go by that chart religiously.
OK, maybe I’m not so lazy after all…
The table shows the 75-80% range for the IM Run and 90-95% range for the HIM Run using 10k and HM times from Daniels VDOT Tables:
My V.dot this year is/was 58. I ran 1:27:xx and 1:28:xx for my 2 HIMs, both of which I was disappointed w/ my run splits, since I felt like I had more in me.
Like Trevor sez, assuming similar courses, fitness, taper, pacing, etc.
Playing with numbers:
Slowtwitch equivalance formula
100 yds swim = 1 point
1 mile bike = 1 point
1/4 mile run = 1 point
so a 1/2 im is
2112 yds = 21 points
56 mile bike = 56 points
13.1 mile run = 52 points
total = 139 points.
A marathon = 104 points.
Argument: You will have spent more effort getting to the start of the run than you spend getting to the halfway point in a marathon. (albeit a more pleasant effort). My conclusion is that you should use the conversion to marathon pace as a better predicter of actual performance.
Can anyone who can actually read these conversion tables (not me) confirm or refute this?
I agree with the 3-5 minute estimate, at least that is what the difference has been for me. Did an open half mary 2 weeks before Baja 70.3 this year. Ran 1:25 mid in the half mary and ran 1:29 high off the bike in the HIM.
This delta has been pretty consistant throughout my triathlon career.
I think % makes more sense than minutes to account for the fact that people have different abilities. Someone with 1:15 open ability will slow down fewer minutes, but a similar percentage, to someone with 1:55 open ability.
So I would say 5-10% slowdown would be appropriate. More than that, and you biked too hard, or you didn’t do enough run training, or both. Less than that, and you biked too conservatively.
Very interesting chart. N = 1 - When I was at my best, the chart was bang-on in terms of the numbers/times that I could run at that time and consistantly recorded in races - a VDOT of 64
my open half PR is 1:26.xx compared with a 70.3 PR of 1:31.xx.
anytime the difference is > 5-10mins (depending on course) I am either severly undertrained or I went too hard on the bike…
My limited experience…
July 1/2 IM run time = 1:35
September 13.1 time = 1:28
Both were hilly courses. I went out too fast on the half marathon and blew up near the end, so I probably lost a minute there. On the other hand, the weather was near perfect in September for the half marathon, but hot and windy for the half IM. So a seven minute differential seems right. That is within the range others are suggesting.
Victor
Come awwwn… we all know Marathons cant be run in 90 degree heat… look what happened in Chicago!? 
I agree with the above posters, even for BOP runners (me):
Half Mary: 2:01
HIM Run: 2:04
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First off: Thanks for some great information!
Now it’s time to get a bit crazy and hijack my own thread…
Switching from running to cycling. If a person were able to average around 25 mph for the cycling leg of an olympic distance tri. what would be a fair average to aim for during the cycling leg of a HIM. Again, assume that the course/conditions are similar and that training has been properly done. As always, thanks in advance for the great info.
What does VDOT stand for?
Wow, that chart looks very, very accurate. At least for me that is…
I think this depends a lot on how much tri experience you have. People who only lose 3-5 minutes probably have quite a bit of tri experience to nail the bike pacing, the nutrition and everything else. I lost about 15 minutes – though it’s hard to compare courses and conditions.
around here it’s the Virginia Dept of Transportation
i think it’s a VO2 MAX ranking
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The chart was way off for me…of course I did my first HIM this year. I did a couple 1/2 marrys over the last couple years 1:29 and 1:33 and my run in the HIM was about 2 hours. I bonked a bit and conditions were Chicago Marathon like. Nonetheless…I don’t see better than 1:45 on a good day.
I think conditions and conditioning are hard to apply to the chart. I was fresh as hell coming off the bike and running over 8 min pace feels like walking…yet, it happend.
ADW
The chart is gone:(
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I think this depends a lot on how much tri experience you have. People who only lose 3-5 minutes probably have quite a bit of tri experience to nail the bike pacing, the nutrition and everything else. I lost about 15 minutes – though it’s hard to compare courses and conditions.
Everyone talks about bike pacing being the culprit as if there is no swim.
The reason everyone talks about bike pacing is because we can see metrics from power meters. Most people have zero clue about how to pace the swim and completely overcook their race before they get to T1. It’s swim + bike fitness plus swim+bike pacing + on bike nutrition. Once we nail all that the best pacing for half IM if almost the same as average pace or open marathon. Or half marathon + ~5min on a perfect day, but 8 min is still Ok.