Oxygenaddict Triathlon Podcast · Rob Wilby

FTP, TSS, Indoor vs Outdoor Riding & Bike Power vs Endurance (Listener Q&A) | Ep 583

·30 min·1 clip

Half the Ironman field walks the marathon in pain: usually pacing errors on the bike, not fitness.

Coach Rob Wilby answers an athlete question about bike pacing discrepancy: simulation shows 2mph faster speeds than real-world data, creating unrealistic race expectations. Rob explains the 280 TSS (Training Stress Score) framework as universal budget for marathon energy preservation in Ironman, regardless of athlete speed. Fitter athletes ride at 82-83% FTP for 4 hours = 280 TSS. Slower athletes ride 35-40 TSS/hour for 8-8.5 hours = 280 TSS. Half the Ironman field walks the marathon; most due to bike pacing errors, not fitness. Power meters essential for accurate TSS. Heart rate estimates add 10-20% margin of error. Any ride exceeding 280 TSS will compromise marathon with 99% certainty.

As heard by us

Clear long-course pacing advice that keeps the marathon in view, not just the bike split.

This episode takes a narrow athlete question and turns it into something useful for long-course pacing. Coach Rob Wilby settles on a controlled TSS target of 280 or less, then explains why race-day speed can look better than training when junctions are managed, roads are closed,…

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Why you'd press play

Turn FTP and TSS into a bike plan that keeps your marathon strong.

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