Ironman and Half Ironman Percentage of FTP on the Bike

When we do get back to racing in 2021, what is the percentage of our FTP that we should shoot for both the full and half Ironman distances on the bike? I am assuming it would be our normalized power numbers on the bike since the courses vary in elevation.

Thanks so much for an incredible product, love that you keep improving the product every day. Cheers! Pete

IIRC, the general rule of thumb is:

70.3: ~75-80%
140.6: ~70-75%

Your experience and strengths will alter those percentages…I have done 70.3’s over 80% and still been able to run well, but the bike was my strength.

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These charts are floating around the net and a pretty decent guide. Definitely want to try out whatever target you set in training and adjust based on your strengths and weaknesses.



so just to confirm. the above charts are showing the TSS for each event’s bike?

I take a comparable NP divided by FTP and get a percentage. Then look at the appropriate column. the number in the box is the expected TSS for that time?

but what good does that do me in preparation?

From the source.

The idea is that there’s a cap on how much TSS you can accumulate on the bike and still run decently. You would use these charts to see how riding at different IF (using something like BestBikeSplit) would affect your TSS and if it puts you in the theoretical “red”. Obviously this is just a guide so use it as a starting point and try it out in training.

It helps alot with your preperation. Knowing the TSS of your bike will help set up your long rides and ensuring you do enough long rides meeting your TSS goal and higher. Also, one step harder, is finding out your KJs for the IM Bike and hitting those numbers in training 2-3x before the event.

IME, most triathlete do not do enough long rides at and harder than their TSS and KJ budget and their race day ride ends up being their harder ride.

Also, these are guidelines. IMO you need to play it on the conservative side depending on your ability due to glycogen depletion. The best way is to do 2-3 IM simulation like days with longer runs OTB to see if your pacing and nutrition plan is appropriate. This is also, IME, something most triathletes don’t do enough of.

What is your current FTP in w/kg? What IM are you planning on doing?


Fantastic advice, I appreciate this kind of help, I think for me the nutrition is key so I am experimenting now with eating properly on the bike and not over drinking like I have done in the past. This will give me some good guides to measure the effort on the bike.
I am a MOPer with a little over 3w/kg, hopefully higher in October for IM California.

oof. another metric i need to stress over. So if I’m 1 hour into a 6 hour bike, how could I possibly estimate what my bike leg’s TSS is going to be (or adjust my power to hit that goal TSS)?

I understand having a goal wattage that is a percentage of my FTP. i dont understand how you can predict your overall TSS mid-bike.

Hi, welcome and maybe you’d be best moving this into the Ironman training thread?


You don’t need to concern yourself with TSS during the race; just use it for planning before. If you think the bike course will take you 6 hours, look at the charts above and select a TSS that is in the right range. I am assuming you are a first timer, so 6 hours in the dark grey would give you a target TSS of 269-286 which corresponds to an IF of 67-69% (of FTP). But this is just the starting point! Now you have to get out there and log some longer rides near this IF and make sure it works for YOU and your nutrition plan.

FWIW, I have found the tables to be spot on for me.

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So much THIS…your race day ride should feel almost easy compared to your training rides. Drives me insane when I see athletes saying “Oh, I’m doing my long ride at my IM pace”. NO…you should be doing those rides at a higher intensity than your planned race pace. That let’s you set-up your run on race day.


I’ve done a full IM at .82 IF (300 TSS), and a half at .92 (187 TSS). Didn’t walk any of the runs and they certainly weren’t spectacular (3:19 and 1:27), but based off my training splits I don’t know that I could’ve done much better if I had eased off the bike pace a bunch. Running mileage/training had been hampered by injury, which was a bigger factor imho. With that said, I have a solid background in endurance cycling…so being on the bike for 4.5hrs and/or going pretty darn hard for 2hrs was kind of a regular weekly thing. YMMV

With that said, I don’t know how much I agree with the post above me. Doing your long rides at a higher intensity than race pace (and potentially also incorporating some sort of brick to get used to running off a long bike) would be CRUSHING. I can’t go out and do rides at .8+ IF for 3-4hrs and then accomplish anything productive for 2+ days after. I don’t know if I even could do that at the end of a long week of IM training.

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The Friel Charts above are a good guideline. General rule of thumb for 70.3 is 0.7-0.8 IF, the faster you are on the bike and the more confident you are in your run the higher you can go above 0.8.

It also depends on your ability to pace and to adjust your effort mid-race. A 0.8 IF evenly paced is much more forgiving than having to deal with a VI of 1.2 or greater. Also, some days you feel strong, others you don’t, pushing the upper limit of IF requires the ability to adjust mid race, to know when you can push and when it might be better to back off.

I’ve began riding around 0.74 when I first took up 70.3 racing a few years ago, this year I rode 0.82 and 0.83 followed up with two sub90 runs, so definitely not overbiked.

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TSS = IF^2 x time in hours.

If you have a target time of 6 hours and a target wattage (need to convert this into a % of FTP), then you know what your TSS will be.

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