Ironman Bike Training: 10 Key Sessions

Why Your Ironman Bike Training Matters

Training for an Ironman is a massive undertaking, and building a rock-solid cycling foundation is crucial to success. The bike leg alone covers 180.2 km (112 miles) — and how you perform on the bike can make or break your race day. Cycling is the longest discipline in an Ironman triathlon, both in distance and in time spent racing. Nailing your bike training improves not only your bike split but also sets you up for a strong marathon. Poor bike pacing, lack of endurance, or nutrition mistakes can destroy your run. That’s why it’s critical to balance long aerobic rides, race-specific intervals, strength work, and nutrition practice. Here’s how to structure your sessions for success!

In this post, we’ll dive into 10 essential Ironman bike sessions that build endurance, strength, race-specific fitness, and confidence for the big day!

The 10 Essential Ironman Bike Sessions

1. Long Endurance Ride

Purpose: Build aerobic capacity and train fueling over race duration

Warm-Up: 15 min spin
Main Set: 3–4 hr @ Zone 2
Cool-Down: 10 min easy spin

2. Broken Tempo Ride

Purpose: Accumulate steady race-pace work in manageable blocks

Warm-Up: 15 min spin
Main Set: 3 x 30 min @ Zone 3 (10 min easy spin between)
Cool-Down: 10 min easy spin

3. Double Threshold Set

Purpose: Increase top-end aerobic power under fatigue

Warm-Up: 15 min spin
Main Set: 2 x 20 min @ Zone 4 (5 min easy spin between)
Cool-Down: 10 min easy spin

4. Over-Under Intervals

Purpose: Train body to shift between tempo and threshold demands

Warm-Up: 15 min spin
Main Set: 5 x (5 min @ Zone 3 + 5 min @ Zone 4) (5 min easy spin between)
Cool-Down: 10 min easy spin

5. Big Gear Endurance

Purpose: Build muscular strength and steady-state control

Warm-Up: 15 min spin
Main Set: 4 x 15 min @ Zone 2 in a big gear (low cadence) (5 min easy spin between)
Cool-Down: 10 min easy spin

6. Progressive Race Prep Ride

Purpose: Progress effort through race-day zones to simulate build

Warm-Up: 15 min spin
Main Set: 30 min @ Zone 2 + 20 min @ Zone 3 + 10 min @ Zone 4
Cool-Down: 10 min easy spin

7. Long Tempo Ride

Purpose: Sustain Ironman pacing under controlled pressure

Warm-Up: 15 min spin
Main Set: 90 min @ Zone 3
Cool-Down: 10 min easy spin

8. Brick Simulation Ride

Purpose: Prepare for Ironman bike-to-run transition

Warm-Up: 15 min spin
Main Set: 2 x 20 min @ Zone 3 + 15 min @ Zone 4 (5 min easy spin between)
Cool-Down: 10 min easy spin
(Transition jog optional)

9. Tempo + Threshold Combo

Purpose: Combine mid-race control with strong finishing effort

Warm-Up: 15 min spin
Main Set: 40 min @ Zone 3 + 15 min @ Zone 4
Cool-Down: 10 min easy spin

10. Indoor Trainer Session

Purpose: Hit key intensities with high control and no coasting

Warm-Up: 15 min spin + 3 x 1 min build
Main Set: 6 x 6 min @ Zone 4 (3 min easy spin between)
Cool-Down: 10 min easy spin

Bonus Tip: Mix Indoor and Outdoor Sessions

Indoor trainers allow precise control over efforts and intervals, while outdoor rides develop handling skills and real-world adaptation. Incorporate both for a complete cycling program!

Remember: Consistency, progressive overload, and smart recovery are the keys to building your Ironman bike fitness.

FAQs

How many bike sessions per week for Ironman?

Most athletes train 3–4 bike sessions per week, balancing long rides, intervals, and race simulation.

What FTP should I aim for for Ironman?

There’s no single target FTP — it depends on your background. However, most aim to race at around 65–75% of FTP for the Ironman distance.

How important is bike nutrition practice?

Critical! You must train your gut to handle calories, fluids, and electrolytes under exertion to avoid bonking or GI issues on race day.

Final Thoughts

Mastering the Ironman bike leg is all about patience, consistency, and smart training structure. Use these 10 sessions to build your endurance, power, and confidence — and set yourself up for a strong marathon too!

Which of these key bike sessions will you focus on first to level up your Ironman training?

Always consult with a medical professional or certified coach before beginning any new training program. The information provided is for educational purposes only and is not a substitute for personalized advice.