# Golden Cheetah CP Curve - Question



## bikesaredangerousmmk (Dec 30, 2013)

Could someone explain the the CP curve on Golden Cheetah to me? I just finished a ride today, and for a portion of the ride (2 hours), my average power and normalized power were 190 watts. Yet, the value graphed for 2 hours on Golden Cheetah is only 153 watts. What am I missing? Thanks.


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## Guod (Jun 9, 2011)

bikesaredangerousmmk said:


> Could someone explain the the CP curve on Golden Cheetah to me? I just finished a ride today, and for a portion of the ride (2 hours), my average power and normalized power were 190 watts. Yet, the value graphed for 2 hours on Golden Cheetah is only 153 watts. What am I missing? Thanks.


I just looked through my CP and I can't find a spot where my best effort was higher than the CP curve. The majority of it is within 5w or so, but never above it.

Have you tried closing, loading, and recalculating the CP curve?


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## Srode (Aug 19, 2012)

Where are you getting the information that your average and normalized power was at 190 watts for 2 hours from? Make sure you click the the date for the ride you just completed on the left, if you are on the previous ride entered it will show that on the CP curve.


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## bikesaredangerousmmk (Dec 30, 2013)

The interval data on Golden Cheetah shows the correct avg. and NP values for that stretch, as do my Garmin head unit and the data on Garmin Connect. I tried closing and reopening, but there's no change.


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## Srode (Aug 19, 2012)

Just checked a file I loaded yesterday with 2 intervals and the average power is off by 10%, lower on the CP curve than the interval so similar but yours is a much larger difference. I checked the power curve for the ride on Strava and it matches the results from Golden Cheetah and the interval data matches between the 2 also. I normally don't use intervals, just the whole ride so I checked ride averages vs CP curve for a few others and they also read about 10% lower on the CP curve. My only thought is perhaps CP is including zero power during stops and the average power is only moving time? If it's not that, I'm lost.


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## bikesaredangerousmmk (Dec 30, 2013)

Checked to make sure: my Garmin is counting zero time. Also, I was pedaling the entire time and closely watching power.


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## Got Time (Jan 23, 2009)

You might want to ask this on the GC mailing list.
Which version of GC do you use? Which CP model do you use?
With the 2 point CP model the CP line can easily be below your best effort for various interval lengths.


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## bikesaredangerousmmk (Dec 30, 2013)

GC 3.0.2. Win 7


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## Srode (Aug 19, 2012)

Got Time said:


> Which CP model do you use?
> With the 2 point CP model the CP line can easily be below your best effort for various interval lengths.


How would one figure out which CP model is being used and how is it changed if needed?


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## [email protected] (Sep 12, 2008)

Srode said:


> How would one figure out which CP model is being used and how is it changed if needed?


On the CP chart move your mouse to the upper left corner of it and then click "more"... "all chart settings"... "cp model" tab... and then the CP model drop down lets you select from the different models... i'm using the Extended CP myself


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## Srode (Aug 19, 2012)

I tried that - there isn't any CP Model tab. When I click on the triangle I don't get 'more' just all chart settings. It's Version 3, but maybe there's a more current version 3 than what I am using. Can't anything with more detail about the version either.


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## Got Time (Jan 23, 2009)

Again: You might want to use the GC mailing list... the GC developers etc are on that list.

Anyway, AFAIK different CP models are only available since 3.1.


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## liversedge (Jul 31, 2014)

bikesaredangerousmmk said:


> Could someone explain the the CP curve on Golden Cheetah to me? I just finished a ride today, and for a portion of the ride (2 hours), my average power and normalized power were 190 watts. Yet, the value graphed for 2 hours on Golden Cheetah is only 153 watts. What am I missing? Thanks.


Critical Power is similar to FTP, it is how hard you can go for a long time, without fatigue. It generally is slightly higher than FTP, but not much.

It is derived from your best power for 1min and 10min from your bests data in the version of GC that you use (3.0.2). 

In v3.1 we changed the defaults to use 2min and 20min bests to estimate CP.

If the CP estimate is below your actuals for longer durations it is because you have no all out efforts for the 1-10 minute range and thus it underreports.

I would recommend getting 3.1 if you're keen to work with such models and also watch the first few minutes of this to get a better understanding of the core concepts: 





Regards,
Mark


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## liversedge (Jul 31, 2014)

And this video for the CP chart in 3.1


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