Does Race Winner's IF (Intensity Factor) = My Pacing Strategy (MTB 100)

Regarding a long event (12+ hours) is it a valuable strategy to attempt to mimic the winner’s IF (Intensity Factor) as a pacing strategy for myself? So if the winner finished in 10 hours at an IF of 0.59, is it reasonable for me to pace at the same IF knowing that my race will be 12+ hours? Should it be less, 0.58, 0.55? Is it better to be safe and start at a lower IF then adjust at mile 90 if need be?

For context this is a MTB event (Marji Gesick) of 103-108 miles, 12,000+ feet of climbing, and 85-90% technical single track. The winner’s IF last year was 0.59% for a weighted average (NP) of 226w. If I were to match that IF my NP pace would be 175w.

Last year’s course:

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I wouldn’t try to copy the winner’s IF unless I wanted to mimic their race strategy, style, and duration.

You’ve already suggested your duration will be 20% longer than theirs was - this alone means that the same IF will not apply to you

To further differentiate - it is likely there will be significant pacing differences between the two of you - surging vs TTing, etc.

You may well end up with a similar IF to them, but using them as a target is probably not the best bet


I think the pacing will be roughly the same (winner vs me), not much surging in this event when 70% will be z2 and under:

Is your IF meaningful in other races, and can you pace by IF in training? I don’t really know about mtb, but I do wonder if the ‘intervals’ (time pedelling hard) are long enough on technical single track to give useful NP, and IF. I might be wrong, but I think the way NP is calculated, it isn’t usually recommended to use it for effords under 10 mins.

I’m looking for an effort of about 12 hours, if I’m lucky. I’ve never trained or ridden for much over 9 hours and I typically race XCO (1:10 - 2:20 hours), so I’m looking for my ceiling power and approximate NP for a rough guide. I want to be able to look at these numbers every 10 miles or so in the first 70 miles to ensure I’m not going too hard.

So if a .59 IF is a reasonable pace, (175w for me), and I see my NP for the first 20 miles is 225, then I know I need to back it down a bit. Or am I misunderstanding how to use IF? Similar to what @Jonathan and @Nate_Pearson did for Leadville pacing strategy.

I thought a 0.65 IF would be a reasonable goal for me to guide my power output, but then I saw the winner’s IF of 0.59 and it had me rethink it all.


Sounds reasonable to me. I also set a climbing wattage ceiling for myself. I think it’s those harder efforts that don’t feel hard in the moment that really catch up with you later in the race.


I would think if you are out on the course longer IF needs to be lower than the race winner. Being able to hold a higher percentage of ftp is a trait that will separate the winners from the rest of us.

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Did you get a chance to test your theory? I’m listening to the Successful Athlete’s Pod with Keegan Swenson and he and @Jonathan are discussing his pacing being 0.7IF. I understand he’s a world class athlete, but I’m curious how it scales.

Umm, not really, lol. My effort had so much hike-a-bike, suffered from heat exhaustion and cramps, and pushed my bike through a muddy thunderstorm for the last 1:30. So it’s hard to gather any useful pacing data. The only thing I learned is that was horrible! This was my effort:


This is gospel. I’ve done races where I followed this and other races where I went by feel only to end up feeling like complete hell in the end.

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What wss your goal power? Plus 10%?

For me it was altitude adjusted FTP. I would ride up to that but tried everything I could to stay under threshold the entire 9 hours on the bike.

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That sounds very reasonable. Having not ridden a power meter outside, how hard was it to keep below ftp on the single track and punchy climbs?

In the Midwest it is next to impossible. You’d have to run a 28x50 and even then you’d be over threshold at times. The idea is to minimize this as much as a possible and to ensure you don’t start off too fast. I use my PM as a governor early on and as a quick reference check when I feel my legs a little too much. However, when the trail is punchy and/or technical climbs sometimes there is no choice but to put out 400+ watts in Eagle gear.

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Agreed, it really depends on the course. There are times however when your race brain says smash up that 2-3 minute climb to get it over with but you have to tell yourself to slow down and regulate your effort. If there is a short steep section, it is what it is, but even there maybe you go 100 watts over FTP but regulate yourself to not go over anymore than necessary.

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How did you deal with the heat exhaustion?

I have no way of telling, but I’m assuming I was just in the beginning stages. Unzipping my jersey and slowing down to start. I had my wife as support with a cooler of ice and towels. At a stop, I poured ice water over my head and face and held an ice cold towel around my neck. Put ice down the back of my jersey. Then continued on with ice cold drink mix. I think that stopped it from getting worse but the damage had been done and really zapped my energy. I’d say I was a mess for about another 2 hours then I seemed to come around a bit. Well, sorta, because I ended up getting a massive quad cramp not much long after. Which was the first cramp I’d ever had.

Crazy how it can zap your energy so much. Do you do a lot of ultra endurance? What was your fluid intake like?

I usually do one MTB 100 per year. I typically race the local XC series (10 races). I used Hammer Perpetuem and Hammer Endurolytes, but had stomach issues during that race and got behind on nutrition. I have since moved on to GU Roctane.