Ironman IF and hills

If I am racing a hilly Ironman (Coeur d’Alene) and want to race at 70IF but on downhills I can’t keep the power up where it needs to be to keep my IF at 70, should I make up for that by going above my goal power up hills? Meaning while climbing should I push the power so that the total IF is 70? I did Lake Placid and kept power all the same and because the descents were big and I couldn’t keep up any power and my IF was below my target. The run is my strength and the bike is my weakness. Hope this makes sense.

I’d monitor NP as a proxy for IF in this situation. I forget how IF is calculated, but I imagine a bike leg with an NP of 70% of FTP would be very, very close to .70 IF. It’ll be a bit of a balancing act going harder uphill to compensate for easy downhills (which I’d do) without overdoing it and letting NP get too far away from AP, but I think keeping an eye on NP will help with this.

I never tried to keep IF in a tight window. But it always was. I just had a steady pace on the flats and would increase the climbing about 20%. If I would spin out on down hills that is when I would fuel up and get a little rest to save it for the run. Remember IM is all about the bike because it is all about the run!

Agree with @Artsosa

The downhills are where you can generally conserve energy rather than ‘make-up’ time. For hilly races I’d try to have a ballpark target for flattish parts of the ride and an idea of a cap you don’t want to go over on the climbs, unless they are steep enough that you just need to get over them whatever that takes.

Once up to speed on the downhills is the time to coast, soft pedal and, if you can, eat. Whatever your power/IF ends up being is just what it is. My goal in any IM bike leg has been to get around as fast as is sensible using as little energy as possible rather than try to have goals around how much I think I can manage.


@JulianM pretty much hit the nail on the head…set a cap for what you won’t go over on the climbs and stick to it ( unless the grades prevent it).

Some like to set a 10% extra cap vs their target power on the flats (and maybe -10% on the descents).

I’m aero enough that when I did IMWI, I never worried about pedaling downhill…I would pass people coasting who were pedaling. Use the descents to recover slightly, eat / drink and refocus.

IMO, IF should be a byproduct of your pacing efforts, not what you guide your efforts by. Use Best Bike Split to help determine what a good pacing profile looks like for you and your goals.