Dynamic Pacing Strategies during the Cycle Phase of an Ironman Triathlon
Six well-trained male triathletes raced the 180-km bike leg of an Ironman on SRM power meters. The flat, three-lap out-and-back course with steady wind allowed lap-by-lap and headwind-versus-tailwind comparisons. Average power, cadence and speed all fell significantly from the first to the last 60-km lap. Power, cadence and speed did not differ between headwind and tailwind sections, but torque and speed varied more into the wind.
Participants
n=6 well-trained male triathletes (abstract: "six well-trained male triathletes"); bike split 5 h, 11 ± 2 min, in the top 10% of all finishers.
Protocol
Bicycles fitted with SRM power meters recording power output, cadence, speed and heart rate.
Course: flat, three laps of 60 km out and back, relatively consistent wind (17-30 km/h).
Comparisons: the three consecutive 60-km laps, and headwind vs tailwind sections.
Key Results
| Variable | Change with laps (P < 0.05) |
|---|---|
| Average power | 239 ± 25 → 203 ± 20 W |
| Cadence | 89 ± 6 → 82 ± 8 rpm |
| Speed | 36.5 ± 0.8 → 33.1 ± 0.8 km/h |
| Headwind vs tailwind | Headwind | Tailwind |
|---|---|---|
| Average power, cadence, speed | not significantly different | — |
| Deviation (SD) in torque | 6.8 ± 1.6 N·m | 5.8 ± 1.3 N·m (significantly lower) |
| Deviation (SD) in speed | 2.1 ± 0.5 km/h | 1.6 ± 0.3 km/h (significantly lower) |
| Median power frequency | 0.0480 ± 0.0083 | 0.0531 ± 0.0101 (tended to be higher) |
The variation (SD) in power and cadence did not change with laps.
The authors read the pattern as a nonlinear, dynamic pacing strategy.
Practical Application
Six well-trained male triathletes (top 10% of finishers, 5 h 11 min bike split) on SRM power meters faded lap by lap over a flat Ironman bike course — average power from 239 to 203 W, cadence from 89 to 82 rpm, speed from 36.5 to 33.1 km/h — and did not ride harder into the headwind than with the tailwind. Even good long-course triathletes do not hold their opening watts for 180 km; expect the last third to be slower and plan the first lap so the fade is small, not so you have "banked" time.
Into a headwind these riders held the same average power but their torque and speed became more variable; they did not surge into the wind.
Inference, not tested here: whether the lap-by-lap fade was a choice or fatigue cannot be told from the abstract, and whether a more even ride would have produced a faster run was not tested (no run data in the abstract).
Not from this paper; the base's own practice: pace the bike for the run — the run is paid for by bike pacing (SYNTH-52, written for short course; for Ironman it is transfer).
Not from this paper: the common advice to push harder into headwinds and on climbs comes from modelling (REF-125); these racers did not do it, and the paper does not say whether they should have.
Limitations
n=6 men, one race, one flat course: no women, no hilly course, no between-race replication.
Lap-to-lap changes may mix fatigue, fuelling, heat and race dynamics; none were controlled.
No run data or overall finish times in the abstract, so the effect of bike pacing on the marathon is unknown here.
Written from the abstract and record metadata only (full text not read).
How this entry was checked and changed
Why this level
field case series, n=6