FTP and Critical Power

Intermediate 10 min read 1 views Nov 28, 2025

FTP and Critical Power

FTP (Functional Threshold Power) represents the maximum power a cyclist can sustain for approximately one hour. Critical Power extends this concept across all durations.

FTP vs Critical Power

  • FTP: Single number, practical for zone setting
  • CP (Critical Power): Mathematical model predicting power across durations
  • W' (W-prime): Finite amount of work above CP

Testing FTP

  • 20-minute test: FTP = 95% of 20-min power
  • 2x8 minute test: FTP = 90% of average
  • Ramp test: FTP = 75% of max 1-minute power
  • Field testing: 60-minute time trial (true FTP)

Power Duration Curve

Your best power outputs across all durations create a curve showing strengths and weaknesses. Sprinters have high 5-second power but lower 20-minute power. Climbers show the opposite.

Improving FTP

  • Sweet spot intervals (88-93% FTP)
  • Threshold intervals (95-105% FTP)
  • VO2max work (120% FTP)
  • Consistent training volume in Zone 2

Discussion

Have questions or feedback? Join our community discussion on Discord or GitHub Discussions.
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