I think the half marathon could be a decent predictor only if your bike fitness has you in good enough shape to be relatively fresh coming to T2. All of the run training in the world will not do anything if you do not put yourself in a position to be able to run off the bike.

The difference between 4:00 and 3:40 is pretty big, isn't it?

At any rate, a friend of mine did a 3:32 run at Florida a few years back. His fastest half? I think it was under 1:15, his fastest marathon was around 2:40.

You are right, it is pretty big. At this point, I have no confidence its even possible, but its more fun to be curious and shoot high and work back from there. That's really what I love about this sport - you repeatedly set your sights on something (finishing a sprint tri, finishing an IM, finishing an IM under 11:00, etc) that you'd think, given your background + current abilities, it makes sense that you'd NEVER be able to do, and then after a period of time you actually do it. That said, I don't think I'll be running a 2:40 marathon any time soon (read: never).

This is a good thread, since I have similar questions. I hope that those reading will chime in for both of us. I'd like to run 3:45 at IMWISC, and my half times are just over 1:30. Am I being unrealistic? I have decent bike fitness, if that helps.

Totally agree. The thing is, my riding is significantly ahead of my running at this point because I like it more and do it more. Now I am hoping to lay some additional running onto an solid base of cycling endurance/strength to see what is possible.

A 1:27 open half-marathon predicts an IM run between 3:23 and 5 hours. You're welcome.

Seriously, I think it's all about bike fitness. A 3:40 is not "fast" - it's like 8:30s. If you can break 90 minutes for your half, you have more than enough speed to run a 3:40. As you know, however, the IM run is more about strength running than speed. I like Dan's analogy - something like: "the IM bike is a contest of who can whisper the loudest." Good luck on your half-marathon: hammer it and then see how many century rides you can do between then and August.

If you pace the bike correctly then you can probably post a run split time 20-30minutes slower than your standalone mary time. So lets say you need to run a 3:10 standalone mary. Rule of thumb (which doesn't work for me) is that standalone mary time best case is 2x1/2 mary time + 10 min. So if you can't run a 1:30 open half mary by the time the race rolls around I'd say you have no shot...but I think it'll be tough even if you can run a 1:25 open half.

ot

Plenty of good responses so far. As you know lots of factors go into a successful run, including bike fitness, nutrition plan, weather, bla bla bla.

So, for what it's worth (and it's not worth much), I ran a 3:40 IM marathon, my stand alone marathon times are generally in the 3:00-3:10 range, and my half marathons generally range from 1:23 to 1:28.

Good luck.

I am so glad to see so many correct answers !!!

The only thing I would add -- you need to stay hydrated and propely fueled during the bike to be able to have a good run.

Basically -- You need to put yourself in a position to run well off the bike.

As for a the 1/2 marathon -- Thrown on a heart rate monitor - If you can run the 1/2 marathon at the same pace with the same heart rate and feel like you could turn around and run it again - that is a good indicator.

You're probably already noticed the theme - running fast off the bike is very different from running fast. I did IMLP in 2004 and IMFL last year. My marathon times were 3:40 and 3:35 respectively. FWIW, my two best open marathon times are 2:57 and 2:58. My best half is 1:25, but I haven't pushed for a PR at that distance for a few years now. In the HIM races I've done in the past couple years, I've got a few run splits right around 1:30.

Hopefully this helps you with your goal (and expectation) setting. Good luck at IMC!

I agree with Hickory - comes down to bike fitness. I think predicting an IM Mary time would be pure conjecture based on a 1/2 Mary time. I've run a stand alone mary in 3:07, slowest at 3:29 (hilly). Still had a dismal 4:30 IM Mary once. Plan on adding about 1 hour to your IM Mary unless you have a lot of bike fitness. Running more (i.e. over 50 miles/week) is great, but you still need that bike fitness. I love running and usually place/podium in stand alone running races (under 20K that is), but this year, it will my arse will be parked on the bike seat and I expect my IM Mary time to be a lot better from BIKING more, not necessarily running more.

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Fatigue is biochemical, not biomechanical.
- Andrew Coggan, PhD

Whats up with all the "bike more" advice? Whatever your bike fitness might be (allowing for a few long rides to boost glycogen storage) just target 70% of FT and you should have a shot at being 20-30min off standalone pace. If someone "bikes more" their FT might be 300, if one doesn't "bike more" their FT might be 260. If they target 70% of the appropriate FT the rider should be giving themselves a shot at running their best possible mary.

I think its more pacing (as %FT) than it is bike prep time.

ot

Fastest open 1/2 was right around 1:25 on the end of November 2002. Ran a 3:11 at IMC 2003 and 3:27 at IMH 2003.

experience man, experience. All the numbers in the world don't matter much much to me (especially when all goes to hell at times like at IM FL '05 for me where my heart rate monitor flooded during the swim, tubular flat tire, crashed over a spectator on the run, etc.). I'd love to be a robot, target a zone and execute, but it is often not that simple. Have that deep bike base (thus either going faster on the bike or going easier than 70% and saving for the run) is very important for an Ironman IMHO. My buddy did IM LP last year (first IM): good biker, but only bikes 6:02 (very slow I thought), but ran a 3:28! His best open mary time was 3:04. He was right on.

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Fatigue is biochemical, not biomechanical.
- Andrew Coggan, PhD

Exactly...its the pacing... :)

I can see the case that when the fecal matter hits the spinning blades that it would be hard to not try to compensate for the misfortune by risking a higher %FT.

ot

My run at IMLP last year was 3:37. I ran the Lake Placid 1/2 marathon a few weeks earlier in 1:19.

My best IM marathon time was 3:27 at IMWisco 2004

I'll echo everybody else's answers and say that it's pretty difficult to predict.

But I'll throw out a few for the hell of it...

I'm usually a 3:20-3:30 IM runner (on good days). Last year I rested for one half iron and ran 1:23 off the bike in May then ran a so-so (for me) 3:34 in LP.

I'd say, very roughly given the same weather and course... a rested/tapered open half marathon maybe 8 weeks out from and iron of about 1:20ish should in the ballpark of a 3:30ish run?

You also have to figure in the type of runner you are: I'm more of a strength runner who enjoys hills so that translates well for running off the bike. If you're more of a speed/leg turnover guy/gal you might expect your IM run to be slowed a bit.

Also, figure in bike mileage - for the most part, the stronger the rider, the less your run will fall apart during the 26.2 off the bike.

By the way, don't believe Slick... I believe I saw him cut the course..

No, I just had to pull over to vomit blood.

3:34. God damn it. You out ran me too. On a bad day no less.

I kicked your ass in the water but good though!

like everyone said, its all about how you pace the bike. that said, here's some numbers from my first year of tris in 2002 coming from a running background:

may - 1:19 stand alone half (flat course in toronto), july - 3:45 IMLP (first IM, it hurt), sept - 3:25 IMWI (rode the bike smarter); nov - 2:57 NYC Marathon

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kangaroo -- please do not read or respond to any of my posts

Just to add to chorus here...

My first IM run was bit a of shocker to me.

Half marathon time: 1:24
Marathon: 3:10
IM Run: 4:10

I paced the whole first half of the run, feeling great at 8 minutes per mile, looking for a 3:30 and feeling totally awesome. And then just short of halfway I was standing on the side of the road barfing. Hit me like a load of bricks. Never really recovered until I was horizontal in doorway of the med-tent.

I learned a lot that day. Number one... don't base your IM run on your other run times. It doesn't work.

amen brutha! Your times are very similar to mine (but I avoided the med tent) ;)

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Fatigue is biochemical, not biomechanical.
- Andrew Coggan, PhD

I heard from a friend who had a sister who knew somebody who said you cut the swim too.

Not for nuthin'.

well let me counter point all the people saying it comes down to bike fitness. True, you need bike fitness. But more importantly you need to know how to ride the bike leg smart. You can be super fit and ride super stupid and have a super slow time in the run. Bike fitness and riding with your brains are two different things.

Now for the counterpoint. I don't care how good of bike shape you are in. If you have not done the work in the run to be able to run fast (in IM terms), be able to run the overwhelming majority of the marathon, and not slow down much then all the bike fitness in the world means squat.

You need to be in good running shape to run well, you need to ride smart (which is different than having bike fitness, although more fitness allows for a bigger margin of error) in order to give yourself the opportunity to run well.

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Brian Stover USAT LII
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