3-Hour IRONMAN 70.3 Turbo Bike Simulation

Session Overview

This three-hour indoor bike simulation mirrors the demands of an IRONMAN 70.3 bike leg. Structured around race-specific power zones, it builds the aerobic base, muscular endurance and mental resilience required to hold pace for 90km — then run well off the back of it. Advanced triathletes should complete this session 6–12 weeks out from their A-race.

What You’ll Need

• Smart turbo trainer or indoor cycling setup
• Power meter or ERG mode on your trainer
• Heart rate monitor
• Nutrition: at least 2 bottles (electrolytes + carbs), gels or bars
• Fan for cooling
• Zwift, TrainerRoad, or structured ERG file (optional)

Warm-Up (20 Minutes)

Start easy and build gradually. Include a few short efforts to prime the legs before the structured block begins.

• 10 minutes easy spin at Zone 1–2 (55–65% FTP)
• 3×1 minute at sweet spot (88–93% FTP) with 2 minutes easy between each
• 5 minutes easy spin back to Zone 2

Main Set

This block simulates the pacing demands of a 70.3 bike leg. Hold your 70.3 race power throughout — typically 75–82% FTP. Nutrition discipline is critical: aim for 60–90g of carbohydrate per hour, the same as you’ll do on race day.

• Block 1 (40 min): Steady at 75–78% FTP — build into race effort, focus on aero position
• Block 2 (40 min): Steady at 78–82% FTP — your 70.3 race power, hold form
• Block 3 (30 min): Hold 80–82% FTP — replicate late-race fatigue
• Block 4 (30 min): 78–80% FTP — controlled effort, mentally rehearse the run ahead
• Between blocks: 5 minutes at Zone 2 (60–70% FTP) for nutrition and comfort break

Cool-Down (10 Minutes)

Spin out easy at Zone 1 to begin recovery. Keep pedalling smoothly — don’t sit still.

• 10 minutes easy spin at 50–60% FTP, high cadence (90–100rpm)
• Start recovery nutrition within 30 minutes of finishing

Coaching Notes

• Treat this as a dress rehearsal — wear your race kit, use your race shoes, test your nutrition
• If power drops below 70% FTP in the third hour, reduce targets and note where fatigue hits
• Cadence target: 85–92rpm throughout, matching your race day cadence preference
• Consider doing a 20-minute easy run straight off the bike to practise the run-off sensation
• Make it easier: reduce to 2 hours or drop all blocks by 5% FTP