Raymond Britt runs some very interesting analysis and publishes the results on his http://www.runtri.com website.
The most interesting analysis for me is the comparison average swim times in Ironman and 70.3 races. The IM swim times are almost always less than 2x the half ironman swim time.
The bike and run times for IM distance races are always more than double the times for half the distance. No surprise there. I’ve done my own comparison of IM and 70.3 swim times and came up with the same conclusion. But, I can’t find an explanation.
Why do you think someone can realistically expect their IM swim time to be less than 2x their half ironman swim time?
I would guess it has to do with the fact that the time spent getting up to speed / dodging legs / finding a good line etc at the start of the swim remains the same, no matter what the distance. Same with the time spent getting around a buoy in a crowd.
In longer distance races, that time is a smaller percentage of your overall swim time, making the time appear faster.
My two best 1.2 mile swims were my splits at IMFL in 2010. I guess I fall into that category.
That stated, I was in the best swimming shape of my life at IMFL. I probably would have swam a faster 1.2 mile at Syracuse 70.3 had I not sighted to the wrong buoy and veered way of course.
Most IMs are mass start hence great draft packs for most, most 70.3s are wavestarts and don’t seem to have big packs at least in my experience. Also most fulls are wetsuit legal and lot of halfs aren’t
My own experience - IM swims regularly tend to be short. HIM swims regularly tend to be long. I think RDs shoot to get 3.7999999999999999 miles for the IM swim. Whereas for HIM, they just shoot for “at least 1.2miles.”
All that aside, though, the biggest difference, IMO, is that with IM, there is almost always a timing mat right when you exit the water. With HIM, it can be placed quite a ways away. Because, logistically, there are more HIM friendly locales, you end up with races in places that can be a bit more “spread out,” and so timing mats are often further from the swim exit.
But, I will say, I’ve NEVER done an IM where the swim was long. But I’ve done plenty of 1/2s where it was.
Generally you don’t cross a mat in the water so there is the time that you run up the beach. Let’s say it is 1 minute and you swim 30 minutes half, well that is 31 minute half and a 61 minute full.
My guess is going to be the the average Joe tackling an IM is a better swimmer than the aver Joe 1/2 IMer.
In my experience most triathletes are poor swimmers and it is the swim that will keep most from stepping up to the IM distance.
Plus, doubling the distance from 56 to 112 miles is something you have to account for on the bike, and certainly going from 13 to 26 miles on the run is going to hurt you, but IMHO going for a 1.2 mile swim is just not that much different from going for a 2.4 miler. or I guess a better way to say it is I can swim jsut as fast for 1.2 as I can for 2.4 and that is not true for the other disciplines. I’m sure that this is true for most others, and in IM ‘most others’ is a better caliber of swimmer.
It seems to me that the analysis was done by comparing average swim, bike, and run times at various IM and half-IM events. If I am reading the analysis correctly, the reason why the IM swim pace is faster is simple: the average ironman competitor is faster and fitter than the average half ironman competitor. So much faster, in fact, that Joe/sephine average ironman competitor swims 2.4 miles at a faster pace than Joe/sephine average half ironman competitor swims 1.2 miles. This analysis tells us nothing about how individuals will do at ironman vs. half ironman. In order to do this, we would need to compare the times of the same large group of people on half IM and IM courses of similar difficulty under similar conditions.
First of all, not all swim courses are created equal…But if you look at courses that are known to be pretty close, and look at the pro times, then there is a definate gap…Potts usually swims 21+ in a wetsuit 1/2, and 45 in an ironman. He will go 22+ in a non wetsuit swim, and goes 47/48 in Hawaii. That is just about what you would expect the fade and pacing difference to be. What other people do in the exact same races may differ because they are overextending to hold a pack, but for an off the front guy, Andy shows what good pacing should look like…
Not sure if this has been mentioned, but one thing you won’t encounter in an IM swim (beyond the first 4 or 5 minutes) is slower swimmers, which are EVERYWHERE in wave start 70.3 races…and they do disrupt your rhythm and change your line in the water.
I agree with those that have said that IM athletes tend to better swimmers than their 70.3 brethren as it’s a much longer swim.
I don’t necessarily think that the mass start n
Makes for better drafting. The mortal combat that happens at the start and the crowded conditions you see with sob many swimmers in the water at the same time makes it more difficult to get clean water I think wave starts permit faster swimming.
So if 70.3 races produce swim times that are greater than 1/2 full IM swim times seems to me you’ve got better overall swimmers in th IM distance who can overcome the tough conditions.
A small part of that timr difference lays in the start of the event as well. The first several minutes are spent thrashing your way through the crowd trying to find your line and not drown. Once things string out, you can get in your groove and start rocking. That first few minutes is the same in both events, but it is a smaller part of the longer race. More rock and roll time = faster splits. Similar reason that your relay splits on the track are usually a little faster than your open times.
Also (and I know this is naive, but I’d like to believe it), you would have to imagine that people doing a 2.4 mile swim would be better prepared than those going 1.2.
I bet if they has split timing at the halfway point in IM swims, the first half would be about the same as the HIM swims, but the second half would be faster. At least, on average.
I’m not so sure it’s because HIM courses are hillier. I think they sometimes feel that way because more of them are in one or two loops, rather than point to point. Nice try tho’
The first several minutes are spent thrashing your way through the crowd trying to find your line and not drown. Once things string out, you can get in your groove and start rocking.
This was true in my experience last year at IMLP. I spent the entire first lap bumping and grinding for there were many a swimmers sprinting for position. We ran up on the beach and back into the water for lap 2 and magically the herd had disappeared into a nice line with some small groups.