Chart PMC using estimated FTP/CP?

[Peter Reed]

Long-time GC user, with gratitude for all the folks who give their time to make it work! 

Question (and please feel free to redirect me or point out something obvious I've missed):

As I understand it, the PMC chart uses TSS values that are based on whatever FTP I manually set for a given workout, which for me is always based on the last 20-min test I've done, with a power meter, of course.  Is there a way of making a PMC chart that uses a calculated (estimated?) CP or FTP value instead of my manually-entered most recent FTP value?  A user-defined formula, maybe?

I assume that estimated FTP values will sometimes differ a bit from my last test, especially if I have a failed test for whatever reason, or during the offseason when my fitness is changing but I'm not testing much.  Any advice welcome--thanks!

Peter

[Ale Martinez]

I think you have 2 options:

1.- directly put the formula for TSS using estimated FTP inside PMC functions in a Metrics Trends chart.

2.- define a Custom Metric for TSS using estimated FTP and then use that metric to build a PMC in a Metrics Trends chart.

Option 2 may be more flexible and efficient but 1 should be simpler, formula syntax can be found here: https://github.com/GoldenCheetah/GoldenCheetah/wiki/UG_Special-Topics_Formula-Syntax-and-Expressions, for custom metrics there is an example when you add one and several more searching this forum.

[Peter Reed]

Yes--thanks!  That's about what I was thinking, but I hadn't gotten to the details. :-)  Appreciate it!

p

[Ale Martinez]

TSS can be computed as 100*(Duration)*IF^2, IF is NP/FTP and FTP estimated by the extended model is estimate(ext, ftp), so the code for a custom metric could be:

{

# only calculate for rides containing power
relevant { Data contains "P"; }

# calculate metric value at end

value { 100*(Duration/3600)*(NP/estimate(ext, ftp))^2 ; }

}