I've done two IM races (ICM97 and IMUSA99). Both bike times were around 6:00. My IM Marathon PR is 3:28. My standalone marathon PR is 2:58 (twice).

Martin

bike : between 4.45 (fast course) and 5.30 (slow course)
marathon : around 3.10
stand alone marathon : don't know but I'm guessing 2.40-2.45

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http://www.wimdedoncker.be

Fastest ironman bike split is 5:05

Fastest non-IM marathon is 2:32 and 3:12 in an IM.

Yikes...there are way too many studs on this forum. I feel like poser around them. IM bike 5:17, IM marathon 3:43 (but normally 3:45 - 4:10), flat out marathon 2:48. Clearly, I am ultimately lame in Ironman runs compared to my fresh time.

I was going to post my times, but I am way too intimidated by the studs who have already posted. I think your IM split is a bit slow compared to a very solid marathon time. On the other hand, maybe your marathon time is a bit fast based on your IM bike split.

It all depends on how you look at it.

That's part of the reason for my post...so I could put some things into perspective.

My buddy rode 5:45 at Canada, and runs around 2:53 in a pure marathon. Just another data point....

-TxDude

I agree, lots of fast cats posting...I'll change that :-)

First and only (so far) IM at Wisconsin last year in 6:18

Fastest of five marathons 3:22

I'm not sure what this data tells us. Wouldn't a better question be -

"What is your IM bike split and how does your IM marathon split compare to your standalone marathon split?"

As a newbie to IMs this year I'd love to see how people's bike split effects their potential marathon time.

Of course time is the ultimate measurment that we end up using. However, whatever, your bike split actually is, the critical thing is how much gas do you have left in the tank to run a marathon at the end of an Ironman. That is key. Hvaing a super fast bike split is nice, but being able to run well and strong off the bike is actually a more significant contributor to a "better" finish in an Ironman. Also, stand-alone marathon times are only a good guess as to how you will do in an Ironman marathon run. In many ways they are two completely different beasts the only similarity being they are both 26.2 miles long.

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Steve Fleck @stevefleck | Blog

There was a good story about that in Triathlete a few years ago. Some guy from Reebok entered the Ironman. He was a National class marathoner and predicted he would lose time on the swim and bike but would have the fastest run of the day based on his marathon times. He ended up "running " around 4 hours and was very humbled. He also bragged about a triathlon he had done earlier in the year where he had a faster run split than the overall winner(which happened to be me).

Hey buddy, thats why they call it tri-athlon!

I'm looking for general fitness indicators - such as a pure non-IM marathon time and how that compares to an IM bike split.

If you told my you run a 3:30 pure marathon and are able to ride 5:45 in an IM, I would think that my biking is lagging WAY behind it's potential.

The pure marathon time is just a fitness indicator. I think there is a corelation. I bet there is also a corelation between someone's 10k time and their half ironman times. That would be an interesting chart.

In other words, someone with a 10k PR of 45 minutes is probably not posting a 5 hour half IM time.

-TxDude

I have known sub 2:20 marathon runners to struggle big time in an Ironman marathon. As I said, they are two different kinds of running. Turn the thing around. I have heard many say that Lori Bowden or other, really good Ironman marathon runners could blitz a stand-alone marathon. My guess is that relativly speaking the stand-alone marathon times of those people would not measure up to quality of the run split that they can lay down in an Ironman marathon.

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Steve Fleck @stevefleck | Blog

Didnt Mark Allen try to qualify for the Olympic trials marathon during his year off from Ironman in 94? I seem to remember him dropping out around 8 miles well off the pace. I totally agree that it is a different animal altogether. Ironmans are routinely won with run times in the 2:50 range. That pace is more about holding it together and strength than running speed.

Speaking to that last point...

I did my first IM last year (the Vineman), and I learned the hard way what 112 miles on the bike does to one's marathon time. I'm a strong swimmer and a decent runner, but weak on the bike. So my slow bike split (6:58) didn't surprise me. My painfully slow marathon -- 4:50! -- shocked the hell out of me.

My marathon PR is right at 3 hours, and I can do a 3:30 marathon pretty much any time. I was hoping to finish the IM in around 12 hours, and part of that calculation was a guess that I could run a 4-hour marathon. An hour slower than my PR, a pedestrian 9:00/mile pace -- sounds easy! And leaving T2, I was at 8 hours exactly, right on target. I stayed at 9:00 pace for all of three miles; the remaining 23 miles was a slow, death-shuffle jog from one aid station to the next.

I simply didn't understand how hard it is to run 26 miles after riding 112. I do now!

Steve Nichols

I guess my only point was that someone can easily sacrifice their IM run for a great bike split. So I don't see any good way of using the times you asked for as a general fitness indicator. What does it mean if someone says "IM bike split 5:15, standalone marathon 2:50"? If their IM run split was 6hrs then I'd guess they pushed WAY too hard on the bike - making the bike split a bad indicator of general fitness. If they did the IM mary in 3:30 or so then I'd say they paced pretty well.

On ST it seems the bike split is the only thing people really care about. I'm pretty sure someone could post a RR showing a '2hr - 4:45 - 7hr' IM and be roundly lauded for having a great race.

OT

I might not have been clear about the intention of my initial post.

I am NOT trying to correlate any of this to an IM run time. I'm trying to correlate the IM bike potential of a person based on their pure marathon run time.

I'm doing this unscientifically with just a quick poll question. But if I were to actually collect this data and complile it into a spreadsheet I might find something like:

pure marathon times 2:40-3:00 equate to an IM bike time of 5:20-5:50

pure marathon times of 3:20-3:45 equate to an IM bike time of 6:15-7:00

So, if I run a 3:30 marathon it might not be realistic for me to expect to be able to ride 5:30 in an Ironman because I'm just not a good enough athlete overall.

See my point?

-TxDude

No personal experience yet, but two thoughts that I have not yet fully integrated. First, Joe Friel's Triathlete's Bible has a comment that an IM marathon (in a supposedly well paced race) should be about 20% longer time-wise as compared to a straight marathon (pg 133). One caveat, the author also describes a marathon split of 4:07 as "mostly a walk". Maybe it is for him, but definitely not me. Second, in the Kona bike survey on Slowtwitch there is a fascinating table which includes the information that the average run to bike time ratio is around 0.7. One large caveat is that this is based on the world's best ag'ers and pros. Bike time and run time constitutes two variables with only one equation, so variance from the ratio is not explainable. However, it seems to me if the Triathlete's Bible comment is valid, that these two comments combined should provide some insight as to whether your run time is slow or not.

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5:57 bike IMLP

3:28 Pacific Shoreline Marathon, it qualified me for Boston!

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Paul, you are correct. Mark Allan tried to qualify for the Olympic trials at the Berlin marathon. Him and Maffetone boldly predicted a 2:17, but like most first time marathoners, Allan had his first exposure to ironquads (or stumpquads as I call them), unable to put his legs forward and eventually dropping out !

I think there is limited correlation between a flat out marathon and an Ironman marathon. If you are fast at Ironman marathon, you likely have a good fresh marathon capability, but if you are good at a fresh marathon, you may not ever be a good Ironman marathoner. Why ? Because two different energy systems come into play in a 2:30 to 3:00 marathon compared to a 9:00 to 10:30 Ironman. It is the same difference as that between people who are studs in Olympic tris but can't seem to carry the same speed over to Ironman racing....at least this is my excuse for slow Ironman run splits that don't measure up to my fresh marathon, Olympic or half Ironman tri running capabilities :-)

I see what you are trying to get but I don't think it'll tell you want you want. Does that make sense? :)

The IM run time is all about how you choose to ride your bike.

Someone who didn't manage their race well could say "IM bike - 5:30, marathon - 3:10" but their IM run might have been 5hrs (but you didn't ask). That same person might have managed their race well and said "IM bike - 6hr, marathon - 3:10" and had an IM run time of 3:45. Which bike split would be a better indication of general fitness for that person? I'd say the 6hr IM bike and 3:10 marathon would be the indicator/correlation you are interested in. My point is that you'll get bad data without knowing the IM run because an "IM bike split" is very dependent on how an athlete decided to pace it and what trade-offs they might have made.

OT

Guys,

From my own personal experience, don't compare times. with all the different courses and different climates, you can simply not compare like you can compare a stand alone marathon. NY is slow but the CR is still only about 2-3 above WR. The fastest biker at IM Klagenfurt bikes 4h14 and the fastest at Embrun bikes 6h flat. I ran my best Ironman-marathon this year in Malasyia, yet it was more then 10' slower then my actual PR. So don't just go on the figures, this is the wrong sport to do this!!

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http://www.wimdedoncker.be

OT,

Ya, I thought of that too. Someone might go super conservative on the bike so that they could run a faster marathon. Another might have a plan to hammer the bike and just surive the run. So using their IM bike times to compared to their pure marathon times would not be apples to apples.

As I said, I'm not being very scientific...:)

-TxDude