When your legs start to feel heavy towards the end of an Ironman 70.3, the natural instinct is to push harder. Many athletes shift into a bigger gear, slow their cadence, and try to muscle their way to the finish.
Unfortunately, that’s usually the opposite of what your body needs.
One of the simplest ways to maintain speed while reducing muscular fatigue is to keep your cadence high and your pedal stroke smooth.
Why Cadence Matters
Cadence is simply the number of times your pedals rotate each minute (RPM). As fatigue builds, many athletes unknowingly allow their cadence to drop. The result is that every pedal stroke requires more force.
That extra force places greater stress on your quadriceps, glutes, and calves—the very muscles you’ll soon rely on for the run.
By maintaining a slightly higher cadence, you spread the workload across more pedal revolutions. Each pedal stroke requires less force, helping to preserve your legs for the kilometres still to come.
Think Efficiency, Not Power
An Ironman 70.3 isn’t won by producing the highest power output on the bike.
It’s won by arriving at T2 ready to run.
A smooth cadence helps you:
- Reduce muscular fatigue.
- Maintain consistent power.
- Ride more efficiently into headwinds and on rolling terrain.
- Keep your legs feeling fresher for the half marathon.
This doesn’t mean spinning wildly with no resistance. Instead, aim for a cadence that feels smooth, controlled, and sustainable—generally somewhere around 85 to 95 RPM for most athletes.
The exact number isn’t important.
What matters is avoiding the temptation to grind a heavy gear simply because you’re getting tired.
Practise It Before Race Day
Like every race skill, cadence should be trained—not discovered during your event.
During your longer rides, pay attention to how your cadence changes over the final 30 to 45 minutes. If you notice yourself slowing down, consciously shift to an easier gear and bring your cadence back up.
You’ll often find that your heart rate changes very little, yet your legs immediately feel smoother.
Those small adjustments can make a significant difference once you begin the run.
Ride the Bike So You Can Run Well
Remember, the bike leg is not an event on its own.
Its job is to prepare you for the run.
Every decision you make on the bike should increase your chances of running strongly, not simply getting to T2 a few seconds sooner.
A smooth, efficient cadence is one of those decisions.
Final Thoughts
Late-race fatigue is inevitable, but fighting it with a bigger gear rarely ends well. Instead, focus on rhythm, efficiency, and maintaining a smooth pedal stroke.
Your future running legs will thank you for it.
Need Help With Your Ironman 70.3 Training?
Preparing for an Ironman 70.3 is about far more than completing the sessions. Smart pacing, efficient technique, and good race execution can make the difference between simply finishing and having the race you’re capable of.
If you’d like some personalised advice on your training or race plan, I’d love to help.
Book a free, no-obligation coaching consultation and let’s chat about your goals: