determine BIKE FTP
The renowned physiologist Dr Andrew Coggan, defined the concept of Functional Threshold Power (FTP) as "the highest power a rider can maintain in a quasi-steady state without fatiguing for approximately 1 hour". Although different testing protocols will produce different results, and the precise range of watts will fluctuate from day to day, your FTP will typically coincide with what we term - the Anaerobic Threshold (AnT).
In the Tri-High Performance system, Power training levels for cycling are determined by percentages of your FTP (although certain workouts use 5 minute power as a reference instead). The more experienced you become as an athlete, the less you will need to perform assessments in order to determine this threshold. An experienced athlete can intuitively 'feel' when they are riding in a quasi-steady state they could maintain for approximately 60 minutes. However, less experienced athletes will often require frequent assessments to establish their hour power.
Unfortunately, it is not typically practical to execute an uninterrupted 60 minute TT on a regular basis. Therefore, we recommend using a 30 minute TT to establish FTP. Although no assessment protocol (other than a 60 minute TT) is perfect, changes in your power output over a 30 minute duration, will always correlate very well with changes in your FTP. You can therefore use this assessment to monitor improvements in your Anaerobic Threshold (AnT).
Prior to the assessment, ensure that you are highly motivated, your power meter is charged and calibrated, you are well hydrated, and well fuelled on carbohydrates. Although I recommend that you weigh yourself on a daily basis anyway (primarily to monitor hydration levels), you must ensure that you weigh yourself prior to any FTP assessment. Without a record of your power to weight ratio for each assessment, you will never have a full picture of your fitness levels.
To determine your FTP, you should use your average power from the final 20 minutes of the 30 minute duration. However, if the first 10 minutes was at a lower power output than the final 20 - you should take an average of the entire 30 minutes instead. This caveat should discourage you from seeking to overly inflate your FTP, by taking the first 10 minutes too easy.