Download this free Microsoft Excel programme, by James Huntington, which is based on the work of Doctor Andrew Coggan, so that you can calculate normalized power (NP), intensity factor (IF), and training stress score (TSS).

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NP (Normalised Power) converts highly variable data and returns a figure, which represents the average power of a time trial which would have been equally fatiguing.

TSS (Training Stress Score) ranks the stress of any workout on an arbitrary scale where 100 = 1h at 25-mile time trial pace.

IF (Intensity Factor) represents the average intensity of an entire workout, where 1.00 = 25-mile time trial pace.

By tracking average power, NP, and TSS you can track changes in your fitness when measuring power, especially when power data is highly variable.

Prior to using the calculator, you should ascertain your 1-hr TT power in watts. You should have all your power meter data in one folder (PT setups with this default C:\Program Files\Power-Tap Link\data). Enter the pathname to the folder containing the PowerTap .CSV files you wish to analyse. The filenames must be in PowerTap's naming convention, namely a user name such as USER_DEFAULT_ followed by the date (in country specific DD_MM_YY or MM_DD_YY -- the date will be extracted from the filename hence why the format has to be as expected). The default folder is the PowerTap download folder containing all rides but you could copy race files into a separate folder for analysis. Alternatively, you could set up a folder a for each year that you have data.