It's by Intensity Factor not power; so for instance, if you plan for the IM ride to take you 5 hours (left column); if you ride at x% of FTP (top row) you will incur a given TSS shown in table. Based on the TSS it has recommendations for where you should fall within if you want to run well and you can alter the %FTP you should ride at accordingly. That's the TLDR summary

 

Doesn't that seem contraindicated? The time I would like to ride? I would think that I should set my IF base on recent long rides and let the time be what it is?

This is today's ride:



The IF for 71 miles is 0.89 and it was challenging.

This chart helps you answer the question "how hard (IF) should I ride?"

The major determinant of how hard you should ride is how long you are going to ride.

To use this chart, you need to be able to ballpark your bike leg time. If you can't or won't do that, don't use the chart.

If you do what you suggest, ride at the IF of your recent ride, the chart says that you have absolutely zero chance of finishing the race (unless you find a way to finish the bike leg in about 2 hours probably, but that's off the chart).

Even if you can say that you'll likely ride between, for example, 5 and 6 hours, you can obtain from the chart the range of IFs that you may want to target and it won't be that wide of a range.

Then, try that IF range for large segments of long rides and then run a bit after the ride and see how it all goes.

Note that an IF of 0.89 for almost 4 hours raises a bit of a flag that your FTP may be quite a bit higher than you think it is.

To OP: How did you estimate you FTP ?

let's go!

first, the % is about IF and not Average, so take care that if you go constant Normalized Power is similar to Average Power, but if not, NP would be higher than Avg Power, and so your IF will be higher. Numbers inside the cells are TSS not watts.

The chart is easy, it is not the same to mantain a IF of 80% 4h or 6h. So if at your 80% you will need 6h to complete an Ironman you are in a DNF red area.

So, if you go at 70% IF, you would ensure to spend less than 6h, to be in the grey area.. if you will need more than 6h to complete cozumel bike segment, you will be in a dangerous zona (yellow or orange), you would need to ask youself if you can take the risk because you are a good runner, or if you would need to select a lower IF. Then you need more time.. and so on.

when you select a Power Objective you can estimate the Time you are going to need. Then you can use the chart to see if this Power Objective (IF) is sustainable for the time needed to complete the zone.

A person with a Higher FTP will need less time to complete the Bike at the same IF, so it could afford a higher IF.

and do i understand right that intensity factor is the ration of normalized power:FTP? is that something you could just calculate yourself or is there more to the formula - some sort of trainingpeaks secret sauce?

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https://lshtm.academia.edu/MikeCallaghan

http://howtobeswiss.blogspot.ch/

You’re correct. IF = NP/FTP

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Favorite Gear: Dimond | Cadex | Desoto Sport | Hoka One One

and it seems like the golden rule seems to be a TSS of around 300 is sustainable for an IM bike?

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____________________________________
https://lshtm.academia.edu/MikeCallaghan

http://howtobeswiss.blogspot.ch/

Not quite, 300 would only be for proven strong Ironman runners. 275 is good target. Safe is maybe 255.

if you see the colours, 300 is "yellow" what it means, that it is not for every one.

I take the opportunity to add some "extra" topics to be taken into account,



- you know your FTP, but are you sure about your FTP? take care if your FTP is optimistic (95% of a 20min test, or if it is conservative, 91% of FTP)
- ok, you have done all your calculations, you have done the simulation in Best Bike Split, and it says that for your FTP at 0.71 you will take 5h.... for 252 TSS. Have you tried how these 252 TSS feel? have you tested how this 0.71 IF long ride feel? to drink and to eat in this condition? If not properly hydrated, you could need to adapt your plan
- and the last.. it is not the same to have a IF = 0.7 in "your home conditions" than in "race conditions". For example, in Cozumel is hot and wet.. you would need to adapt the IF, because grey may change to yellow, yellow may change to red...

Ding-Ding-Ding!

Races like Ironman Texas or Ironman Cozumel can be crushing for many athletes because they haven’t seen heat indexes like that in many months.

If you’re from upstate NY and doing IMTX in April, odds are you haven’t seen 85 degrees since September or October of the prior year. So for seven months you have been training in a much cooler climate and pacing yourself by whatever metrics and have a good feel for how those metrics affect you physiologically.

Race day comes in The Woodlands and it’s the hottest and most humid day you’ve experienced in seven months. Let’s say you’re dialed in at TSS of 275 and IF of .72. That’s awesome when “home conditions” are 65 degrees but sticking to those metrics when “race conditions” are 85-90 will likely mean gray turning to red.

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Favorite Gear: Dimond | Cadex | Desoto Sport | Hoka One One

 

From TrainerRoad:

 

I lived and trained in Miami, Florida for about 15 years, then Houston Texas for 31 years.

Are all those rides indoor with Trainer Road or are some of the rides imported from outside rides?

I think you are basing your FTP based on what Trainer Road has estimated but haven't done a true FTP test yet. I would suggest doing either an outdoor one or Trainer Road's indoor 20 minute one to get a better idea of your current FTP.

 

The rides are Trainer Road or imported from real (outside) rides.

Come to think of it, I have not done any FTP test for a long while. Certainly time to do one.

I do feel that my FTP is underestimated as I find TR bike workouts much to easy.

.

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Once, I was fast. But I got over it.

For reference, I'm the same weight as you and I do my Z2 rides around 160 watts. And I'm by no means a strong cyclist. Your FTP is no doubt way too low.

TrainerRoad has an AI FTP detection option that at least for me seems pretty accurate. I would start with that. As another poster said it look like your FTP is set too low, 4 hours at .89 IF should be near impossible to complete for almost everyone.

Here is a link to an article that explains the chart, you may not have seen if you were just looking at the chart.
https://www.trainingpeaks.com/...meter-in-an-ironman/

Were you in Endurance Nation? Your username seems familiar from those days, but more important to the OP's question, yours is the "correct" answer of the what the chart is. Or was. Or what Rich Strauss, who created it originally in his Crucible Fitness days and then transported it to Endurance Nation (from where it then went to unattributed, freely distributed content on the inter webs) intended it to be.

The original version of the chart, circulated within EN, also had a few useful preambles indicating what it should *not* be used as ... again, IIRC, it was/is not a "if I ride XX intensity, I will finish in YYY time" calculator, and should not be used a bike split predictor.

(This table predated Best Bike Split and other bike split guides, but even with those more precise or granular tools now widely available, I still rely on this table to guide racing IF.)

I wasn’t, no. I agree with everything you said about what the chart is not to be used for.

To the OP, there are many ways to ballpark how long the IM ride will take you; from calculations using software programs like mywindsock and best bike split to looking at what you are doing in training, time trials and other races. As I always tell athletes, when using any guidelines, especially if this is your first IM, err on the conservative side.