FTP Testing Demystified: Proven Methods to Track and Improve Your Cycling Power

Overview of FTP

Functional Threshold Power (FTP) is commonly defined as the highest average power a cyclist can sustain for approximately one hour. It represents a rider’s maximum sustainable output—the “red-line” intensity that can be held without fatiguing for a prolonged period. This metric is closely related to the lactate threshold (though not precisely the same) and serves as a practical proxy for the point where lactic acid accumulation and fatigue begin to rapidly increase.

FTP is foundational for training because it determines the upper limit of a cyclist’s steady-state effort. A higher FTP typically translates into the ability to produce more power for time trials, climbing, and long efforts. It also means that riding at a given sub-threshold pace will feel easier. FTP is used for setting individualized training zones and quantifying training load with metrics such as Training Stress Score (TSS) and Intensity Factor (IF). Knowing your FTP lets you pace efforts optimally—both in training and in events—and track your fitness changes over time.

Different FTP Testing Methods

Traditionally, FTP was measured by performing a maximal one-hour effort, but this is both physically and mentally taxing. To address these challenges, shorter or more convenient testing protocols have been developed. Each approach aims to estimate or predict your 60-minute power, offering various pros and cons.

60-Minute Steady-State Test (Gold Standard)

The most straightforward way to measure FTP is the 60-minute all-out effort. Many consider this the gold standard, as it directly reflects your one-hour power without needing formulas. After a thorough warm-up, you ride at the maximum sustainable pace for an hour (indoors or on a steady course outdoors). The average power of that hour is your FTP.

• Advantages
  • Direct measurement: No predictive formula needed.
  • Accurate gauge of true fatigue resistance over 60 minutes.
• Disadvantages
  • Extremely demanding physically and mentally.
  • Requires excellent pacing—going out too hard can cause an early fade, and going too easy will underestimate FTP.
  • Not practical to do frequently; significant recovery required.

Despite being the “true” method, most riders—particularly amateurs—rarely perform a full-hour test outside of an actual race or time trial.

20-Minute Test (with 5% Adjustment)

The 20-minute test is one of the most popular methods, balancing accuracy with manageable duration. In this protocol, you ride all-out for 20 minutes, then take 95% of the average power over that interval as your FTP.

• Advantages
  • Shorter, more manageable than a full-hour test.
  • Correlates well with lab-measured lactate threshold for many riders.
  • Popular and widely available in indoor training apps (Zwift, TrainerRoad, etc.).
• Disadvantages
  • The 95% factor is an approximation; individual physiology can skew the result.
  • Still quite challenging physically and mentally.
  • Requires good pacing strategy—blowing up midway will compromise accuracy.

For most intermediate or advanced riders, this protocol provides a robust estimate of FTP. Beginners can do it as well, though they should pay careful attention to pacing.

Ramp Test (Step Test)

Ramp tests have gained popularity through platforms like TrainerRoad and Zwift. Instead of a steady or extended effort, the rider performs a progressively harder workout, with resistance increasing each minute (often by 20 watts) until failure. FTP is then typically estimated as 75% of the highest one-minute power you can sustain.

• Advantages
  • Very time-efficient and beginner-friendly.
  • No need for a self-paced “all-out” interval; you simply ride until you can’t.
  • Less fatigue compared to a 20- or 60-minute test, making it easy to slot into a training schedule.
• Disadvantages
  • The 75% multiplier is a heuristic; accuracy may vary for riders with unusually high or low anaerobic capacity.
  • May overestimate or underestimate for specific athlete profiles.
  • Primarily practical indoors (easier to control incremental wattage).

Ramp tests are particularly popular among amateur cyclists who may find the 20-minute or 60-minute test daunting or prefer a shorter test format.

8-Minute Test (2x8 Protocol)

In the 8-minute FTP test, you perform two all-out efforts of 8 minutes each, with a recovery interval in between. Your FTP is then calculated by taking either the average power of these two intervals and multiplying by 90%, or by applying a similar reduction to the higher average interval.

• Advantages
  • Even shorter individual efforts, which may be psychologically easier.
  • Provides insight into recovery and repeatability between intervals.
  • Historically used in certain coaching systems (e.g., Carmichael Training Systems).
• Disadvantages
  • The 90% factor is an approximation; results may vary if your short-term power output differs significantly from your true threshold ability.
  • Some riders may pace the first interval poorly, skewing the data.
  • Less widely used now compared to the 20-minute test or ramp test.

This protocol can be useful for riders new to testing but still want a structure more substantial than a ramp test while avoiding a full 20-minute effort.

Alternative Estimation Methods (Data Analysis & Machine Learning)

Beyond traditional test workouts, there are algorithmic ways to determine FTP using ride data:

1. Power Curve Analysis
   • Software like TrainingPeaks (WKO5), GoldenCheetah, and others can model your power-duration curve using multiple rides.
   • Requires a history of maximal efforts at varied durations.
   • Often produces a “modeled FTP” that closely matches test-based FTP for riders who train regularly and produce maximal efforts during normal rides.
2. Machine-Learning Predictions
   • Some platforms (e.g., TrainerRoad’s AI FTP Detection, Xert, Strava, intervals.icu) can estimate FTP by analyzing your ride history.
   • Eliminates the need for a dedicated test day, though you still need periodically hard efforts in your training data.
   • Estimates can sometimes be conservative or lag behind if you improve rapidly, but they provide a convenient, ongoing assessment.

These methods rely on consistent data inputs. They can be very accurate for those who ride hard often and feed the system with enough relevant data. However, they might be off if you rarely perform near-threshold or VO2max efforts.

Comparison of Methods

Here is a quick comparison of the most common FTP test approaches:

60-Minute Test

• Accuracy: High if paced correctly (the “true” measure).
• Physical/Mental Demands: Extremely high, akin to a race effort.
• Suitability: Experienced cyclists or those used to TT-like efforts.
• Practicality: Difficult to repeat often; best done in a controlled environment or race.

20-Minute Test

• Accuracy: Generally very good (95% rule).
• Physical/Mental Demands: Still challenging, but more approachable than 60 min.
• Suitability: Intermediate to advanced cyclists familiar with pacing.
• Practicality: Commonly used, fairly repeatable every 4–8 weeks.

Ramp Test

• Accuracy: Good for many riders; may over/underestimate for outliers.
• Physical/Mental Demands: Moderate until the final minute; shorter test.
• Suitability: Beginners or time-crunched athletes who dislike pacing.
• Practicality: Excellent for indoor testing on smart trainers.

8-Minute Test (2x8)

• Accuracy: Decent if performed and paced correctly with 90% multiplier.
• Physical/Mental Demands: Hard, but split into two efforts.
• Suitability: Novices or those following older protocols (e.g., CTS).
• Practicality: Less commonly used nowadays, though still valid.

Data/Model Estimates

• Accuracy: Potentially very good with ample data; can be off if data lacks maximal efforts.
• Physical/Mental Demands: None in a specific session, relies on existing training data.
• Suitability: Experienced riders who collect power data regularly.
• Practicality: Low stress, continuously updated estimates.

Advice for Amateur and Recreational Cyclists

For amateur or recreational cyclists, the best test often depends on experience, goals, and comfort with intense efforts:

• Match the Test to Your Experience:
  • Total beginners may prefer the Ramp Test to avoid pacing errors.
  • Riders comfortable with steady hard efforts often use the 20-minute protocol.
  • Very few need the full 60-minute test unless prepping for a time trial or race.
• Consider Your Goals:
  • Long-distance event training often correlates better with a longer test (20- or 60-minute).
  • Crit or sprint-focused riders might benefit from shorter tests, but remember FTP is still a key training metric.
  • If you race, your next race’s data might reveal your real FTP—no separate test needed.
• Equipment Availability:
  • Use a power meter or a smart trainer for best accuracy.
  • If you only have a basic trainer, consider virtual power from an app.
  • Outdoor testing can work with a power meter, but ensure a safe, uninterrupted road.
• Don’t Stress the Exact Number:
  • FTP is a tool, not an absolute measure of cycling ability.
  • Consistency of testing matters more than the specific protocol.
  • A small deviation of a few watts in FTP won’t drastically affect your training zones.

Equipment and Software Considerations

Accurate FTP testing requires consistent power measurement, typically from either:

• Power Meters: Pedal-, crank-, or hub-based.
• Smart Trainers: Provide reliable, calibrated power data.
• Apps/Platforms:
  • Zwift: Offers built-in FTP test workouts (20-min, ramp) and automatically detects potential FTP changes.
  • TrainerRoad: Historically used 8-min and 20-min tests, now emphasizes the Ramp Test and AI FTP Detection.
  • WKO5 / GoldenCheetah: Advanced analysis to model FTP from multiple efforts.
  • Xert: Continuously estimates “Threshold Power” in real time or via post-ride data.

If using a smart trainer in ERG mode for a 20-minute test, most platforms automatically switch to “free ride” during the test interval. For outdoor tests, find a long climb or quiet stretch of road that lets you maintain a steady pace.

Best Practices for Testing

1. Preparation
   • Schedule your test when you’re fresh.
   • Get adequate rest and proper nutrition.
   • Avoid hard workouts for 48 hours before the test.
2. Warm-Up
   • Perform a structured warm-up of 15–20 minutes, including short hard efforts to elevate heart rate.
   • Some protocols recommend a 5-minute near-max effort before longer tests to reduce anaerobic contributions.
3. Pacing and Execution (for steady efforts)
   • Start slightly below target intensity, build into it, and aim for a near-steady or slight negative split.
   • Avoid a huge sprint at the end—spiking power late may indicate under-pacing.
4. Mental Strategies
   • Break the interval into smaller segments mentally.
   • Use music or self-talk cues to maintain focus.
   • Control your environment (fans for cooling, minimal distractions).
5. Post-Test Protocol
   • Cool down for 5–10 minutes to aid recovery.
   • Record average power, time, and subjective feel.
   • Update your FTP in training apps and devices.
6. Using FTP for Training
   • Set or adjust your power zones based on the new FTP.
   • Assess how upcoming workouts feel. If they are too easy or too hard, consider re-checking or adjusting FTP slightly.
   • Limit testing frequency to every 4–8 weeks or whenever a significant change in fitness is suspected.

Sources

1. Allen, H., & Coggan, A. (2019). Training and Racing with a Power Meter (3rd ed.). VeloPress.
2. TrainingPeaks (2023). “Understanding Training Stress Score (TSS) and Intensity Factor (IF).”
3. Coggan, A., & Allen, H. (2006). “Power-Based Training Levels and the Concept of Functional Threshold Power.”
4. Friel, J. (2018). The Cyclist’s Training Bible (5th ed.). VeloPress.
5. Zwift (n.d.). “Zwift Workouts and FTP Tests.” Accessed via Zwift in-app resources.
6. TrainerRoad (n.d.). “Ramp Test Protocol and AI FTP Detection.” TrainerRoad support documentation.
7. Carmichael, C., & Rutberg, J. (2003). The Time-Crunched Cyclist. VeloPress.
8. Stern, R. (2015). “Step Test Protocol for Cyclists.” Stern Training.
9. WKO5 / TrainingPeaks (n.d.). “Modeled FTP (mFTP) and Power Duration Model.”
10. Xert (n.d.). “Xert Training Platform and Real-Time Threshold Power.”
11. GoldenCheetah (n.d.). “GoldenCheetah Power Duration Curve and Critical Power.”