Most runners chasing a sub-24 at a US 100-miler have the fitness. What they don’t have is the pacing discipline. The difference between a 23:50 finisher and a 25:30 finisher is rarely fitness; it’s how the first 50 miles got run.
Sub-24 averages out to roughly 14:24/mi. That sounds slow until you remember it includes every aid station stop, every pee break, every gear change, every walked uphill, every dark-of-night moment of self-doubt. Sub-24 is “moderate effort with no major breaks.” The runner who hits 11:30 pace through mile 40 and then sits at every aid station for 8 minutes runs 25 hours. The runner who hits 13:15 pace consistently and is at aid stations for 4 minutes runs sub-24.
The split that works
For most American 100-milers (Western States, Leadville, Rio Del Lago, Run Rabbit Run), the sub-24 split looks like this:
- Miles 0–30: 11:00–12:00/mi pace, feels insultingly easy
- Miles 30–60: 13:00–14:00/mi pace, feels comfortable
- Miles 60–80: 14:00–15:30/mi pace, feels honest
- Miles 80–100: 15:00–17:00/mi pace, hike the climbs, run the descents and flats
That’s a negative split inverted — slow finish, but average to sub-24. The classic mistake is reversing this: 9:30/mi for 30, then walking the back half. That’s a 26-hour finish.
The aid-station math
Six minutes at twelve aid stations is 72 minutes. That’s an entire hour of your sub-24 budget. Cut it to three minutes per stop and you save half an hour. Crewed runners save more — drop bag pre-organized, vest pre-stocked, a chair waiting, food handed to you in your hand without asking.
Most sub-24 finishers have a crew that runs aid stations like a NASCAR pit crew. It’s the unsung half of the buckle.
What sub-24 doesn’t require
It doesn’t require 100-mile training weeks. Most sub-24 finishers peak around 80-85 miles per week. It doesn’t require quad strength workouts in the gym. It doesn’t require carbon-plate trail shoes. It doesn’t require a coach.
What it requires: 24 weeks of consistent training with two long-run days per week, vert specificity (training on grade similar to the race), meticulous fueling discipline, and pacing patience. The boring stuff. Sub-24 isn’t athletic; it’s executional.
The runners we’ve seen miss sub-24 in races where they had it in the legs always tell us the same story afterward: “I went out too fast. I knew I was going out too fast. I felt great. Then I bonked.” The first 30 miles is where the buckle is won — by holding back, not pushing.
One last thing
If you’re chasing sub-24 and have the fitness, don’t try to “feel out” the pace early. Wear a watch with a target pace bar. Discipline yourself to the slower number. Your watch will tell you you’re behind schedule at mile 25 — that’s exactly correct. The schedule is wrong; the pace is right. Trust the math.
The buckle is heavy in the right way. We hope you earn one.
What these sessions assume you are measuring with
Every pace, zone and power figure here needs something recording it. These three cover running, long days and the bike.
Garmin Forerunner 965 AMOLED multisport with the training-load and threshold metrics most of these sessions assume you can see day to day.
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COROS APEX 2 Series GPS Watch Sapphire titanium and the longest battery in its class, which is the deciding feature once a day out runs past a few hours.
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Favero Assioma Uno Power Meter Pedal Single-sided pedal power, the cheapest honest entry into training with watts rather than estimating from heart rate.
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