I am doing my first IM in Cozumel. I consider myself an average cyclist, but a strong runner (26.2 PR: 2:47). Assuming the bike and heat are going to tax me fairly badly, what is an appropriate time goal for the run?
As a further reference, I did a few half races this Summer when my overall time was in the 4:45 to 5:00 neighborhood, and the runs were 1:25 to 1:30.
Thanks
Probably anywhere from about 3:15 to 4.5+ hrs.
A lot of variables here and I am no expert but I am also an average biker and strong runner with a comparable PR (2:43 in Boston this year) IM Choo was my first IM and I biked under control and ran 3:10:xx on a very tough run course, but the weather was perfect. So my IM run was just over 1 min/mile slower than my open marathon and for the most part it didn’t feel too bad.
My whole goal was not to blow up, so I biked maybe a little too easy and my mantra on the run was literally: “easy, easy, easy”. I ran slower than maybe I could have but being my first I wanted to have a good experience and definitely did not want to give back 10/15/20 mins over the last 10miles/10k as so many people seem to do.
I was very happy with my race and execution, take that for what its worth, I hope it helps!
I am doing my first IM
This is the key part of your question for me. Your time goal for the run will be to simply maintain the “easy long run” pace that you’ve been doing in training.
Trust me, it will be a struggle.
You should be looking between a 3:35-3:22 IM Marathon split. I would start with a 3:35 (8:12/mile) pace, slow down through aid stations and get plenty of water/calories, assess how you are feeling at mile 20 and then drop the hammer and fly past everyone for a strong finish!!!
You will not go wrong with this strategy if you come off the bike in good shape.
Ironman is all about EXECUTION on race day. If you’ve done the requisite training, race day should not have any surprises. Bike smart, run smarter. Think to yourself, “I can always speed up but once I start slowing down, game over!” You say you are an avg cyclist and based on your 26.2 time, you are one talented runner. Scroll through any recent Ironman event where the run splits are still up and you will see a field littered with run times that start at x pace per mile and by the end of the run it is x + 2-3’ per mile. If you bike smart and your nutrition is dialed in, you should be in great shape coming into T2. Don’t drop a couple 645-650 miles out of the gate. Run conservative the first few miles, 8’/mile based off your previous times is conservative. Break the course up into 1/4s, run the first 6 at 8’ per mile an asses your situation. If you are feeling good, pick it up ever so slowly, say 5" per mile. Repeat this at 12 and 18. If you start to labor, drop back to the start pace. IF you are still feeling good at 24, let er rip the final 2.2. Coz is flat, so you do not have any miles in there where you have hills to contend with so it should help you dial in your pace and keep it there. Your goal should be to have your fastest mile and slowest mile within 20-30" of each other, with the bulk of your miles pretty much within 5-10" My best IM mary was a 3:30 at IMFL. My fastest mile was a high 7, my slowest, around 820, and the bulk were all around 8’, and never once stopped, not even at the aid stations. Best of luck to you
how much mileage have you been running? If you’ve been running 40-50mpw, then I think a 3:10-3:20 is reasonable. if your plan has to been to leverage your open run strength during training by focusing on swim/bike, then you should probably take your sights down a little bit. I ran 3:09 at IMMT but was running good volume.
Considering it’s your first IM and taking into account the effects of heat, bike pacing, etc., it’s going to be hard to establish a goal pace. The right pace is the one that feels sustainable, and it sure as hell ain’t gonna be 2:47 pace 
You’ll start off your IM run feeling WAY worse than you ever have at the start of a marathon, but the way you feel throughout your IM run will change far slower than it has in your open marathons, and it may even improve. I’ve felt so miserable at the start of a couple IM runs that I didn’t really have a choice but to start feeling better!
This is great feedback. I really appreciate it.
To answer one of the questions, I probably have been running about 35 miles per week (I have been spending a lot of my time on the bike or swimming). I did do something I know everyone here would tell me is a stupid idea ahead of an IM: I ran three marathons this Fall. I do snap back from these races pretty quickly, so at this point, it doesn’t feel like an issue.
I would say a good triathlete runner could hit about 3:10-3:15 with a PR of 2:47 and 2:47 fitness going into the IM.
A 1:30 half IM run usually translates closer to a 3:30 IM run if well executed.
I’m thinking you are a much better stand alone runner than triathlon runner so I’d aim for closer to 3:30.
Everyone slows down in the 2nd half of an IM run so maybe splits of about 1:40/1:50. If optimistic, 1:35/1:45.
I’d have a hard ceiling of keeping first 3 miles over/slower than 7:30. Might Even want to open up with some 8s. I’d probably really try to keep all miles slower than 7:30 though until you hit 20…
I’ve often felt great for the first half of IM runs and it is very very easy to run too fast.
With a heart rate monitor.
I’ve often felt great for the first half of IM runs and it is very very easy to run too fast.
Good advice from Dave.
I agree with others - assuming everything is optimal for a triathlete with this background, about a 20 min or 1 min/mile differential between the stand-alone marathon and best case scenario IM run split is about right.
The challenge is that beyond the 7 - 8 hr mark, most people, and in particular those doing their first IM are into an area of fatigue, and exertion that they have never been. Anything can happen!
When I had my best IM runs, it felt like I had the brakes on for the first 6 miles. Those early miles, and the pace, you go are critical. If you’ve paced the bike well, you should feel not too bad heading out onto the run. The problem is course markings are often off. RPE can get thrown wildly off, as adrenaline kicks in - keep in mind the early miles on the run have the biggest crowds cheering the loudest. Even HRM readings can’t be trusted until you really settle in and get going . . you just have to KNOW that pace.
A session I would always do several times in my final IM prep, was to finish off a long hard bike ride at a running track and then roll right into a 4 - 5 mile run, running on the track trying to nail, that pace with as little input from my watch as possible.
I am doing my first IM in Cozumel. I consider myself an average cyclist, but a strong runner (26.2 PR: 2:47). Assuming the bike and heat are going to tax me fairly badly, what is an appropriate time goal for the run?
As a further reference, I did a few half races this Summer when my overall time was in the 4:45 to 5:00 neighborhood, and the runs were 1:25 to 1:30.
Thanks
I am a 2:48 26.2 pr dude, ran a 3:10 a few times at the IM distance, with most IM’s between 3:15 - 3:25. I have become a good cyclist and that hasn’t changed my running much.
So I may be comparable to you. Do you train with power on the bike? What time do you plan to split and at what % of your threshold?
No matter what you do, don’t go out too quick on the run and really hold yourself back. You might find it easy to go at a 6:30 pace and die. That would suck. I always find that I fade no matter how I pace so aim to start out about 10 sec/mile faster than you plan to finish.
Again - The IM distance is all an experiment. Don’t expect anything, but just go out and do your best. Good luck.
You’ll start off your IM run feeling WAY worse than you ever have at the start of a marathon, but the way you feel throughout your IM run will change far slower than it has in your open marathons, and it may even improve. I’ve felt so miserable at the start of a couple IM runs that I didn’t really have a choice but to start feeling better!
Agreed.
This is why, it’s really hard to compare open marathon running and the marathon you run in an IM - other than sharing the same distance, they are very different!
When I had my best IM runs( came close to going sub-3 a few times), I seem to recall them being broken up into 3 parts. The first 1/3 was a bit of a struggle but, as noted in another post, I would hold back and keep the brakes on always, when in doubt backing off on the pace. In the middle third, was often where the best running would happen. The stride would open up, and it would feel more like “normal” running. Then the final third - really the last 10K, the cumulative fatigue of the day would start to really pile-up, and it would be a supreme effort to maintain the pace that back at 20 - 25K seemed not that bad.
I’d start doing little tricks with myself doing a countdown of the distance to go. At this point you really are working aid-station to aid station, hoping that the finish starts to come up. The great news is that IF you have paced your whole day well, and you can run that last 10 - 20K on the run strongly and with good pace, you will be passing MANY people. This is often in competitive IM races where AG podium and KQ spots are sorted out.
I am doing my first IM in Cozumel. I consider myself an average cyclist, but a strong runner (26.2 PR: 2:47). Assuming the bike and heat are going to tax me fairly badly, what is an appropriate time goal for the run?
As a further reference, I did a few half races this Summer when my overall time was in the 4:45 to 5:00 neighborhood, and the runs were 1:25 to 1:30.
Thanks
My HIM run times are also in the 1:30 range
However I am a strong biker
I have 5 IM run times between 3:18 - 3:30 (3:18, 3:24, 3:29, 3:29, 3:30). I feel like I could probably hit 3:15 on a flat, cool course.
The consensus here seems to be that i should be targeting something like 3:15 or slightly higher.
When I look at the pros putting up sub-3:00 times, how do they do that? Are they 2:30 marathoners on a stand-alone marathon, or is it just that the bike doesn’t destroy them the way it would hurt a less accomplished cyclist?
They workout as many hours as most people work (in the extreme cases). That allows a person to have an astoundingly high aerobic threshold. The top professionals are probably not capable of running THAT MUCH faster than their IM times (this has been beaten to death on this forum, and there are some obvious exceptional examples to what I just said) but they can swim/bike/run at 85-95% for 4-8 hours.
I am doing my first IM in Cozumel. I consider myself an average cyclist, but a strong runner (26.2 PR: 2:47). Assuming the bike and heat are going to tax me fairly badly, what is an appropriate time goal for the run?
As a further reference, I did a few half races this Summer when my overall time was in the 4:45 to 5:00 neighborhood, and the runs were 1:25 to 1:30.
Thanks
My HIM run times are also in the 1:30 range
However I am a strong biker
I have 5 IM run times between 3:18 - 3:30 (3:18, 3:24, 3:29, 3:29, 3:30). I feel like I could probably hit 3:15 on a flat, cool course.
Rob, I think you are aa good example of someone who runs really well in IM, better than many others with even faster open Marathon splits. Likely related to all the usual things like fitness, pacing, nutrition, execution, etc.
My PR on a HIM run was 1:32. PR on IM Marathon was 3:33. Both hilly courses. I have no idea what my open Mary time is though, and while I am curious about it, I see zero chance of me running a marathon in the near future.
I do think there are definitely better IM runners than others with similar open marathon splits. So many factors at play 
You’ll start off your IM run feeling WAY worse than you ever have at the start of a marathon, but the way you feel throughout your IM run will change far slower than it has in your open marathons, and it may even improve. I’ve felt so miserable at the start of a couple IM runs that I didn’t really have a choice but to start feeling better!
Agreed.
This is why, it’s really hard to compare open marathon running and the marathon you run in an IM - other than sharing the same distance, they are very different!
When I had my best IM runs( came close to going sub-3 a few times), I seem to recall them being broken up into 3 parts. The first 1/3 was a bit of a struggle but, as noted in another post, I would hold back and keep the brakes on always, when in doubt backing off on the pace. In the middle third, was often where the best running would happen. The stride would open up, and it would feel more like “normal” running. Then the final third - really the last 10K, the cumulative fatigue of the day would start to really pile-up, and it would be a supreme effort to maintain the pace that back at 20 - 25K seemed not that bad.
I’d start doing little tricks with myself doing a countdown of the distance to go. At this point you really are working aid-station to aid station, hoping that the finish starts to come up. The great news is that IF you have paced your whole day well, and you can run that last 10 - 20K on the run strongly and with good pace, you will be passing MANY people. This is often in competitive IM races where AG podium and KQ spots are sorted out.
I disagree about feeling so bad at the start of the run. In my case, I am so happy to get off the bike (decent cyclist), out of areo position (neck hurts, butt hurts, etc) along with the cheers out of T2, that its feels like I am flying at the start of the run.
As for the rest, I agree with Fleck’s comments.
Finally, every time I was “chasing a time/pace”, I messed up big time. Too many variables. My best IMs (only 6, incl. KQ) are the ones I barely looked at time/pace other than not exceeding my target HR or power on the bike. Being your fist IM, I suggest you should keep it as simple as possible and simply shoot for “not walking during the marathon”, other than aid stations. Being a strong runner, you should reach the finish very satisfied. Good luck!
One thing that really hasn’t been brought up yet is proper nutrition, which is crucial to a solid IM run. For me, I have an easier time taking in calories on the bike than while running. My bike is pretty solid, but my last IM run became a struggle because I didn’t take in the nutrition I needed early on the run.
The first 10k of the run should feel very easy if you paced the bike properly. This is the time to really hold back (as many have said), running SLOWER than goal pace. Hydrate at each aid station, take in your calories, then in the middle miles of the run begin to settle into your goal pace.
A friend of mine has really nailed his nutrition down over the past two years and taken his IM run from the 3:20’s to a 3:04 at Whistler and a 3:11 at Kona this year. His fitness has improved a little, but he attributes much of his success to nutrition and proper pacing on the bike and first half the run.
In your position, I’d aim for somewhere around a 7:50-8:00 pace for the first hour or so, then if you are still feeling good drop the pace to the 7:35-7:45 range and try to maintain that when the going gets tough during your last hour of running. I’ve learned that ah huge part of an IM run is mental. If you have done the proper training, you should know what you are capable of. Pacing properly and getting the calories in will only go so far if you can’t focus when your body is telling you to slow down. The mind is quite powerful, and if you listen to what it says at the end of an IM you’ll probably slow down. If you can think back to good training sessions that you nailed and feel that you can run through the pain you may surprise yourself with what you are capable of.