We (tx @ryandev !) have added support for custom formulas on custom charts on the activity timeline. These are simple math expressions and (hopefully!) easy for non-software developers to write (similar to the /fitness chart support).
This example shows altitude adjusted power (alt_watts) less power (watts) indicating how many watts are “lost” due to the altitude:
Click “Charts” to bring up the activity timeline charts dialog, then click “+Chart” to create a new custom chart:
Click “Add Plot” and search for “Formula”:
Click “Edit Formula”:
Use the “Plots” drop down to insert plots into the expression:
This expression shows how many watts are being “lost” due to the altitude:
You can also reference fields on the activity. Here is an expression for % of heart rate reserve:
(heartrate - activity.icu_resting_hr) * 100 / (activity.athlete_max_hr - activity.icu_resting_hr)
Note that “%HRR” is built in.
