In a Half Ironman (70.3), success on the bike — and in the entire race — depends on a far more complex set of qualities than simply having a high FTP. What matters is durability, efficiency, intensity control, and the ability to preserve your legs for the run. Below is a breakdown of the qualities that truly matter in 70.3 and how important each one is.
1. Fatigue Resistance ⭐⭐⭐⭐⭐
The most important quality for a 70.3
This is the ability to hold high power after 2–3 hours of work, when glycogen is low and the neuromuscular system is fatigued.
Even if your FTP is high, if you lose 20–25% of your power after an hour of riding, your race will fall apart.
To ride well in a 70.3, you must sustain 75–85% of FTP for 2–2.5 hours and then run a half marathon afterward. That requires a very specific form of endurance.
Why it’s critical:
The last 30–40 km of the bike decide your entire run.
Poor fatigue resistance = slow bike + catastrophic run.
This quality is not built with FTP intervals but with long steady work (2–3 hours Z2–Z3, tempo bricks, steady-state efforts).
2. Efficiency & Technical Stability ⭐⭐⭐⭐
In triathlon, conserving energy matters more than producing maximum power. An efficient athlete burns less glycogen at the same wattage — and therefore runs faster afterward.
This includes:
stable cadence,
avoiding power spikes on climbs,
smooth pacing,
relaxed and sustainable aero position,
minimizing muscle fatigue needed for the run.
3. Aerodynamics (CdA) ⭐⭐⭐⭐
Over 90 km, aerodynamics often matter more than absolute power.
An athlete with 260 FTP but great aero can ride faster than someone with 300 FTP but a “parachute” position.
In triathlon, every extra bit of drag costs minutes.
4. FTP as a Base Metric ⭐⭐⭐
Important — but not decisive.
A higher FTP:
raises your overall power ceiling,
makes race pace feel easier,
determines what percentage of that power you can hold for the entire distance.
But the longer the race, the weaker the connection between FTP and actual performance.