You can be the fittest you've ever been and still ruin a triathlon in the first 20 minutes of the bike. Pacing is the single highest-leverage skill in long-course triathlon, and most age-groupers — and plenty of pros — get it wrong.
We've had Sebastian Kienle, Lionel Sanders and Alistair Brownlee on the Roadman podcast, and every one of them said some version of the same thing: the bike leg is not about producing your biggest number. It's about producing the right number, evenly, for as long as the course demands, while leaving enough in the tank to actually run the marathon.
Here are the FTP percentages that work, why most athletes overshoot them, and how to pace when power data isn't available.
The FTP Percentages That Actually Work
These are target normalised power ranges as a percentage of your current, honestly-tested FTP. Age-groupers should sit at the lower end of each range. Stronger, more durable athletes can push toward the top.
Sprint (20-30 min bike leg): 85-95 per cent FTP. Almost a time trial. You can sit close to threshold because the run is short enough to tolerate a heavy bike.
Olympic (45-75 min bike leg): 80-90 per cent FTP. Still aggressive. You'll be uncomfortable by the back end but the run is short enough that some bike fatigue is acceptable.
Middle distance / 70.3 (2:00-3:00 bike leg): 75-82 per cent FTP. This is the range that breaks people. Too low and you're bleeding time; too high and you walk the half marathon. Most age-groupers should be at 75-78 per cent.
Ironman (4:30-7:00 bike leg): 70-76 per cent FTP. The longest and most unforgiving pacing window in endurance sport. Stronger cyclists with weaker run legs should be at the bottom of this range.
If your FTP is set correctly, these numbers feel far too easy in the first hour. That's the point. If they feel hard at 30 minutes, you're going to have a very long afternoon.
Why Most Triathletes Go Out Too Hard
Three reasons, all of them fixable.
The first hour feels effortless. You've tapered, you're fresh, you're high on race-day adrenaline. Producing 76 per cent of FTP at that moment feels like cruising. Your legs say "we can do more than this." Your legs are liars.
Other people's bikes pass you. Watching someone drop you at 10km is the most expensive emotional tax in triathlon. If your plan said 210 watts and you're now doing 225 because someone in a flashier helmet went by, you just bought yourself a slower run.
You tested FTP wrong. A lot of triathletes are pacing off a two-year-old 20-minute test they did feeling fresh on Zwift. If your actual current FTP is 20 watts lower than the number in your head, every pacing target is wrong by 20 watts.
Olav Bu said it on the podcast: the plan is a hypothesis, the race is the test. Execute the plan. Measure the result. Adjust. Heroics in the first hour destroy more Ironman runs than any nutrition mistake.
Variability Index: The Metric Nobody Tracks
Variability Index (VI) is normalised power divided by average power. It tells you how smoothly you rode. VI 1.00 means you held a perfectly even wattage. VI 1.10 means you surged a lot.
Target VI for triathlon:
- Flat course: under 1.05
- Rolling: under 1.07
- Properly hilly 70.3 or Ironman: under 1.08
Research from Hunter Allen, Andrew Coggan and long-course coaches going back 15 years shows a clear pattern — riders with low VI run faster off the bike, even when average power is identical. Surging is expensive. Hitting 320 watts up every rise because it feels efficient adds anaerobic cost that shows up 2 hours later as the shuffle.
Two practical VI rules: on climbs, cap your power at 110 per cent of target (never 130). On descents, pedal lightly rather than coasting. Smoothness is trainable — most of it is discipline, not fitness.
Pacing by Heart Rate and RPE When Power Fails
Power meters die. Garmins crash. Bars come loose and rotate your head unit into the void. You need a backup.
Heart rate as a ceiling, not a target. Decide pre-race on an upper HR limit for the first 60 per cent of the bike leg ("don't exceed 150"). Heart rate drifts upward in heat and with dehydration — your legs will feel fine at a HR that indicates trouble. Use HR to veto going too hard, not to tell you how hard to go.
RPE in three words. Sprint/Olympic: "uncomfortable but sustainable." 70.3: "comfortably hard." Ironman: "annoyingly easy." If an Ironman bike leg feels comfortably hard in the first two hours, you're already in trouble.
Lap splits. Know roughly how long each major course section should take. If you're hitting checkpoints 5 per cent fast, you're overcooking it. Simple, but nobody does it.
Sanders has talked about this specifically on the podcast — he pre-commits to a power range and a HR ceiling and refuses to exceed either for the first third of the race, no matter what the field does. The discipline is the race.
Terrain-Adjusted Pacing
A flat Ironman bike at 74 per cent FTP is very different from a hilly Ironman at 74 per cent FTP. On rolling or hilly courses, the climbs tempt you to dump your pacing plan.
Rule of thumb: on any climb longer than 2 minutes, cap power at 10-12 per cent above target. On anything shorter, ride it at target — you can't save meaningful time on a 60-second rise, but you can waste anaerobic capacity trying.
On descents, don't coast. Keep easy wattage flowing (30-50 per cent of target) to keep the legs moving and blood circulating. Dead descents mean heavy legs at the bottom.
This is where your aero position earns its keep — descents and flats are where unaggressive pacing plus good aero save the time that aggressive pacing in the bars can't.
Pacing and Nutrition Are the Same Problem
You can't pace properly if you can't fuel properly. If you go out too hard, your gut shuts down, you stop absorbing carbs, and the inevitable bonk is now layered on top of the pacing error. Our triathlon bike nutrition guide covers the fuel side. The short version: fuel the plan, don't fuel the heroics.
Key Takeaways
- Target FTP ranges: Sprint 85-95 per cent, Olympic 80-90 per cent, 70.3 75-82 per cent, Ironman 70-76 per cent. Err low.
- The first hour should feel too easy. If it feels right, you're already too hard.
- Keep Variability Index under 1.05 on flat courses and under 1.08 on hilly ones — surges cost you run time.
- On climbs, cap at 110 per cent of target. On descents, keep the pedals turning gently.
- Use heart rate as a ceiling, not a target. Use RPE plus lap splits as your power-meter backup.
- Test your FTP honestly every 6-8 weeks. Training and pacing off a stale number ruins races.
- Learn FTP zones properly and pair pacing with a real bike nutrition plan.
- Want a coach to lock in your pacing targets before race day? Check out our coaching options or apply to work with us.