FTP & Critical Power from Golden Cheetah

The foundations for successful riding

FTP & Critical Power from Golden Cheetah

Postby twizzle » Fri Jan 08, 2010 1:09 pm

O.K. - confused here.

My best one hour power in a race, on a number of occasions, has been around the 320w mark, with a best of 329 which just happened to fit in with my 2x20 on the trainer. And I use 350W as my est. FTP for training purposes following on from my 421w-for-14-minutes in a recent time trial. But GoldenCheetah's "Critical Power" calculation based on 3 and 20 minute "best power" efforts estimates my critical power (FTP) at 403W. Against that is one of the best rides : a 45 minute crit where I was on the front for 27 minutes averaging 358W before the power output dropped - which could have been hydration impacting the performance OR the fact I'd just put in a quick lap when passing D grade and the power output had spiked for a lap. Also, there was the hill climb the other week where I averaged 411W in 11:41, but had to keep moving at the top because the lactate spiked when I stopped and my whole body was on fire.

Anyone got some words of wisdom? Should I use 403w as my FTP for training purposes? According to the quicky research I've done the critical power model is supposed to work on power-to-weight and requires a weight input, but the GoldenCheetah process doesn't have an input for weight.

I just don't think I could actually maintain 403W for an hour. Or is it a case of HTFU?
I ride, therefore I am.
...real cyclists don't have squeaky chains...
User avatar
twizzle
 
Posts: 6382
Joined: Wed Aug 13, 2008 11:45 am
Location: Taking a break.

by BNA » Fri Jan 08, 2010 3:46 pm

BNA
 

Re: FTP & Critical Power from Golden Cheetah

Postby Alex Simmons/RST » Fri Jan 08, 2010 3:46 pm

Refer SOS #8:
http://alex-cycle.blogspot.com/2009/07/ ... ftp-2.html

Body mass is not required to calculate CP, however it is common for CP to be expressed as W/kg, and when using model to predict maximal sustainable power for a given duration, it uses this value.
User avatar
Alex Simmons/RST
Expert
 
Posts: 3430
Joined: Fri May 02, 2008 3:51 pm

Re: FTP & Critical Power from Golden Cheetah

Postby twizzle » Fri Jan 08, 2010 4:43 pm

In the context of Golden Cheetah, it's providing a CP number that's supposed to be the hour value, but there's no weight.

Looking at the CP calculator from the tools menu instead of the CP value on the chart, it looks like the number on the chart is what it thinks I should be able to do, not what I've done, as using the highest observed numbers over time gives me a CP of 348. I would need to pick up my 20 minute power from 370w to 410w to get to the CP value indicated on the chart (403.3w).

I think what this is telling me is "could do better". But at the moment, my actual CP (based on data in the last month) is ~ 350w.
I ride, therefore I am.
...real cyclists don't have squeaky chains...
User avatar
twizzle
 
Posts: 6382
Joined: Wed Aug 13, 2008 11:45 am
Location: Taking a break.

Re: FTP & Critical Power from Golden Cheetah

Postby toolonglegs » Fri Jan 08, 2010 4:48 pm

Yup...I think you actually need to do the testing...not take in from non specific events.
Cheetah gives me a critical power of 353 I think (466 for 3 minutes & 370 for 20 minutes) so pretty close for me.But if my 3 minute power was around my normal results of 420-430 it would kick my CP up to the 370 mark :shock: .Bearing in mind my best 3 minute was part of a 5 minute effort and also the 3rd 5 minute effort over 440w for the day.If I had specifically tested a 3 minute on that day I could have gone close to 500 I am sure :D .
Go and do the HOP :D or two well rested full on 20 minutes or the 16km TT...and then follow it up with a few minutes of fun doing a MAP test.
Image
User avatar
toolonglegs
 
Posts: 14380
Joined: Fri Jun 29, 2007 7:49 pm
Location: Somewhere with padded walls and really big hills!

Re: FTP & Critical Power from Golden Cheetah

Postby toolonglegs » Fri Jan 08, 2010 4:57 pm

Not that I could get anywhere near any of those numbers at the moment! :oops: .
Image
User avatar
toolonglegs
 
Posts: 14380
Joined: Fri Jun 29, 2007 7:49 pm
Location: Somewhere with padded walls and really big hills!

Re: FTP & Critical Power from Golden Cheetah

Postby twizzle » Fri Jan 08, 2010 5:01 pm

On one of the other threads... you will have seen us all scratching our head re. where we can do a 20 minute test without running out of road or getting hit by a car.

Here's something to think about - criterium on the 10'th November. Three minute of 445w and 20 minute of 361w from the one event... giving a CP of 345w

I think this means I need to HTFU - my FTP is above the 350w I've been using for training goals.
I ride, therefore I am.
...real cyclists don't have squeaky chains...
User avatar
twizzle
 
Posts: 6382
Joined: Wed Aug 13, 2008 11:45 am
Location: Taking a break.

Re: FTP & Critical Power from Golden Cheetah

Postby toolonglegs » Fri Jan 08, 2010 5:32 pm

Maybe...send me the .csv file an I will chuck it in WKO+ ...seing that our dimensions :D are pretty close it will give me a pretty good NP.
...but if you are 350 or 360 it doesn't actually change your training numbers by more than 1 or 2 watts.
[email protected]
Also not sure how long the crit was...but when doing the Coogan 20 minute test you have to do a blow out effort first...if your 3 minute effort was part of your twenty minute numbers then not sure how that would skew the numbers.
Image
User avatar
toolonglegs
 
Posts: 14380
Joined: Fri Jun 29, 2007 7:49 pm
Location: Somewhere with padded walls and really big hills!

Re: FTP & Critical Power from Golden Cheetah

Postby twizzle » Fri Jan 08, 2010 5:41 pm

toolonglegs wrote:Maybe...send me the .csv file an I will chuck it in WKO+ ...seing that our dimensions :D are pretty close it will give me a pretty good NP.
...but if you are 350 or 360 it doesn't actually change your training numbers by more than 1 or 2 watts.
[email protected]
Also not sure how long the crit was...but when doing the Coogan 20 minute test you have to do a blow out effort first...if your 3 minute effort was part of your twenty minute numbers then not sure how that would skew the numbers.


I have wko+, I just don't use it. I'll load some data up at work next week to have a look.

Re. the same event, what it should mean is that my 3 minute number is way low and therefore the CP estimated off the one event is low as well.
I ride, therefore I am.
...real cyclists don't have squeaky chains...
User avatar
twizzle
 
Posts: 6382
Joined: Wed Aug 13, 2008 11:45 am
Location: Taking a break.

Re: FTP & Critical Power from Golden Cheetah

Postby toolonglegs » Fri Jan 08, 2010 5:48 pm

Well...if you do the test you will know...you have been wondering for quite a while now.
Image
User avatar
toolonglegs
 
Posts: 14380
Joined: Fri Jun 29, 2007 7:49 pm
Location: Somewhere with padded walls and really big hills!

Re: FTP & Critical Power from Golden Cheetah

Postby Alex Simmons/RST » Fri Jan 08, 2010 6:45 pm

twizzle wrote:Re. the same event, what it should mean is that my 3 minute number is way low and therefore the CP estimated off the one event is low as well.

On the contrary, underestimating your 3-min best power will overestimate critical power (which is the slope of the line) and underestimate your anaerobic work capacity (the intercept).

that's why cherry picking such data from non specific tests is part of the sins of sins articles I referenced.

CP requires dedicated best effort tests, typically one of 3-6 minutes duration and another ~ 20-25 minutes. You can throw in a number in between if you like, provided it really is a best effort. It also requires such tests be done within a reasonable time period of each other, like in the same week.

But putting non best effort numbers in there from non quasi steady state efforts is just GIGO.
User avatar
Alex Simmons/RST
Expert
 
Posts: 3430
Joined: Fri May 02, 2008 3:51 pm

Re: FTP & Critical Power from Golden Cheetah

Postby twizzle » Fri Jan 08, 2010 7:29 pm

Blah. I'm all confused again as to how the models work.

And how the heck do people find the time to do the proper testing??!

And where does Golden Cheetah come up with a 403W figure from?
I ride, therefore I am.
...real cyclists don't have squeaky chains...
User avatar
twizzle
 
Posts: 6382
Joined: Wed Aug 13, 2008 11:45 am
Location: Taking a break.

Re: FTP & Critical Power from Golden Cheetah

Postby twizzle » Fri Jan 08, 2010 8:34 pm

O.K. - the CP number on the CP display is from an estimator that looks at all prior history and tries to apply a curve to the historical data to estimate what it *thinks* you are capable of. No additional info on the web etc., so I might have a look at the source code.
I ride, therefore I am.
...real cyclists don't have squeaky chains...
User avatar
twizzle
 
Posts: 6382
Joined: Wed Aug 13, 2008 11:45 am
Location: Taking a break.

Re: FTP & Critical Power from Golden Cheetah

Postby Ant. » Fri Jan 08, 2010 8:39 pm

(Nothing personal, but) I don't believe you can do 400W for an hour.
Don't bother getting fancy by looking at source codes and everything. 2x20s are your ticket.

I vaguely understand the CP model but wouldn't use it personally. Seems like it's too easy to get wrong, needing to do well rested best efforts, and need to do them within a week of each other, and so on.

I have 3 interval locations. One is a 10km circuit (it's around the block.. 5km streets) with rolling terrain, another is a 6km stretch of road with rolling terrain, and the other is a 6km road pancake flat.
Forget the first spot I mention... I just need to stop and do a U turn every 7-8mins. 2 U turns doesn't impact a 20min effort. Plus it gets you really good at doing U turns :D
Do 2x20s: same power each time = FTP. Maybe round down to the nearest 10W if you're really suffering and burning.


I'm google mapping your location, and I refuse to believe you can't manage to do 2x20s outside. Gundaroo road? I wouldn't complain about having to turn around every 5mins to be honest. It's only a few seconds of coasting.
Cervélo R3
Cervélo P3C
BT Blade
Ant.
 
Posts: 758
Joined: Sun Oct 26, 2008 8:34 am
Location: Perth

Re: FTP & Critical Power from Golden Cheetah

Postby twizzle » Fri Jan 08, 2010 9:09 pm

Neither do I. :)

re. 2x20, easier said than done around here. Gundaroo is a popular tourist destination, the road is narrow and rough as guts...
I ride, therefore I am.
...real cyclists don't have squeaky chains...
User avatar
twizzle
 
Posts: 6382
Joined: Wed Aug 13, 2008 11:45 am
Location: Taking a break.

Re: FTP & Critical Power from Golden Cheetah

Postby toolonglegs » Fri Jan 08, 2010 10:50 pm

Jump on the federal highway?...I don't have any roads 20 minutes long,taking maybe 2 or 3 corners doesn't effect Av much at all...maybe 2 or 3 watts compared to NP for the same time.
Image
User avatar
toolonglegs
 
Posts: 14380
Joined: Fri Jun 29, 2007 7:49 pm
Location: Somewhere with padded walls and really big hills!

Re: FTP & Critical Power from Golden Cheetah

Postby Ant. » Fri Jan 08, 2010 10:59 pm

5km stretch of road, s'all you need :wink: Both of mine are very close to the CBD.
Jump on a popular group ride, and I'm sure they'll go through more than a couple of suitable locations.
Look harder :) Everyone in Perth told me I couldn't do my 20min intervals except if I go waayy out that way. They were wrong.

2x20s are the bees knees.

3 U-turns don't affect AP at all for me, because I'm pretty quick around corners and because the few seconds of coasting is made up for by the few seconds of accelerating (out of saddle for me) over the AP.
Cervélo R3
Cervélo P3C
BT Blade
Ant.
 
Posts: 758
Joined: Sun Oct 26, 2008 8:34 am
Location: Perth

Re: FTP & Critical Power from Golden Cheetah

Postby Alex Simmons/RST » Sat Jan 09, 2010 10:14 am

twizzle wrote:Blah. I'm all confused again as to how the models work.

http://74.125.155.132/search?q=cache:9Q ... =firefox-a
http://www.velo-fit.com/articles/critical-power.pdf
http://teamhealthfx.com/files/7/general/entry1758.aspx

twizzle wrote:And how the heck do people find the time to do the proper testing??!

Pithy Power Proverb: Training is testing, testing is training. - A. R. Coggan, PhD

twizzle wrote:And where does Golden Cheetah come up with a 403W figure from?

Don't know, you'd have to ask the providers of GC.

But if it's commiting one of the Sins of Sins, then it will give you garbage.
User avatar
Alex Simmons/RST
Expert
 
Posts: 3430
Joined: Fri May 02, 2008 3:51 pm

Re: FTP & Critical Power from Golden Cheetah

Postby DanielS » Sat Jan 09, 2010 11:12 am

Alex Simmons/RST wrote:On the contrary, underestimating your 3-min best power will overestimate critical power (which is the slope of the line) and underestimate your anaerobic work capacity (the intercept).


Ahhhhh..... okay something just clicked.

Golden Cheetah provides an estimate for CP from the mean-maximal power plot. It has always estimated mine too high (it says 300W but I'm closer to 280W). I've never done a proper 3-min test so that makes sense now.

The best way I think is to do two dedicated tests, one of which is 20-30 min long, and the other 3-5 minutes, and calculate it directly. Or use one of the spreadsheets out there to do it. There is also a calculator built into GC that you can use if you do a 20 min and 3 min test (under the Tools menu).
User avatar
DanielS
 
Posts: 512
Joined: Sat Apr 19, 2008 8:00 pm
Location: Adelaide

Re: FTP & Critical Power from Golden Cheetah

Postby toolonglegs » Sat Jan 09, 2010 5:20 pm

OK...no real idea :D .But is it suggesting that if your 3 min power is high compared to your 20min then it is just taking a % of the 20 minute in relation to the 3m/20m ratio.Yes Alex is right...the higher your 3 minute power compared to 20 minute...the lower your estimated "critical power".I expect there is more maths to it than that :lol: .
Image
Image
User avatar
toolonglegs
 
Posts: 14380
Joined: Fri Jun 29, 2007 7:49 pm
Location: Somewhere with padded walls and really big hills!

Re: FTP & Critical Power from Golden Cheetah

Postby twizzle » Sat Jan 09, 2010 6:24 pm

toolonglegs wrote:Jump on the federal highway?...I don't have any roads 20 minutes long,taking maybe 2 or 3 corners doesn't effect Av much at all...maybe 2 or 3 watts compared to NP for the same time.


Hmmm - main trucking route, four lane divided highway... where would you like to to turn without waiting for traffic? Actually, if I started the run from Sutton Road back towards Canberra, and then looped over the bridge at Eagle Hawk, I'd only have to dodge a tiny part of the traffic - but it would only just scrape in as a 20 minute run...

Screw it - where can I do VO2Max and LT testing in Canberra?

Or, seeing as all of the estimates using the calculator on reasonable efforts in December come up with a 350 - 360W range, does it really matter if it's five percent (>15w) out when the 20min testing just uses an estimate for hour period anyway?
I ride, therefore I am.
...real cyclists don't have squeaky chains...
User avatar
twizzle
 
Posts: 6382
Joined: Wed Aug 13, 2008 11:45 am
Location: Taking a break.

Re: FTP & Critical Power from Golden Cheetah

Postby Alex Simmons/RST » Sat Jan 09, 2010 7:39 pm

twizzle wrote:Hmmm - main trucking route, four lane divided highway... where would you like to to turn without waiting for traffic? Actually, if I started the run from Sutton Road back towards Canberra, and then looped over the bridge at Eagle Hawk, I'd only have to dodge a tiny part of the traffic - but it would only just scrape in as a 20 minute run...

Uriarra road. Good enough for National Masters TT.

twizzle wrote:Screw it - where can I do VO2Max and LT testing in Canberra?

What for?
User avatar
Alex Simmons/RST
Expert
 
Posts: 3430
Joined: Fri May 02, 2008 3:51 pm

Re: FTP & Critical Power from Golden Cheetah

Postby twizzle » Sat Jan 09, 2010 8:19 pm

Alex Simmons/RST wrote:
twizzle wrote:Hmmm - main trucking route, four lane divided highway... where would you like to to turn without waiting for traffic? Actually, if I started the run from Sutton Road back towards Canberra, and then looped over the bridge at Eagle Hawk, I'd only have to dodge a tiny part of the traffic - but it would only just scrape in as a 20 minute run...

Uriarra road. Good enough for National Masters TT.


Narrow, 100km/h road frequented by bogans... Which is why I've never used it as a training road.


Alex Simmons/RST wrote:
twizzle wrote:Screw it - where can I do VO2Max and LT testing in Canberra?

What for?


Beats the heck out of dealing with SOS 2,3,4,6 & 9 on a regular basis.

What's going to be more accurate - an excellent 2 x 20, or an actual blood lactate/VO2Max test session I can repeat every 3 - 6 months?
I ride, therefore I am.
...real cyclists don't have squeaky chains...
User avatar
twizzle
 
Posts: 6382
Joined: Wed Aug 13, 2008 11:45 am
Location: Taking a break.

Re: FTP & Critical Power from Golden Cheetah

Postby Alex Simmons/RST » Sat Jan 09, 2010 8:31 pm

twizzle wrote:
Alex Simmons/RST wrote:
twizzle wrote:Hmmm - main trucking route, four lane divided highway... where would you like to to turn without waiting for traffic? Actually, if I started the run from Sutton Road back towards Canberra, and then looped over the bridge at Eagle Hawk, I'd only have to dodge a tiny part of the traffic - but it would only just scrape in as a 20 minute run...

Uriarra road. Good enough for National Masters TT.


Narrow, 100km/h road frequented by bogans... Which is why I've never used it as a training road.


Alex Simmons/RST wrote:
twizzle wrote:Screw it - where can I do VO2Max and LT testing in Canberra?

What for?


Beats the heck out of dealing with SOS 2,3,4,6 & 9 on a regular basis.

What's going to be more accurate - an excellent 2 x 20, or an actual blood lactate/VO2Max test session I can repeat every 3 - 6 months?

You're making a mountain out of a molehill.
User avatar
Alex Simmons/RST
Expert
 
Posts: 3430
Joined: Fri May 02, 2008 3:51 pm


Return to Training

Who is online

Users browsing this forum: No registered users



Popular Bike Shops
Torpedo 7 Torpedo7 AU
Ground Effect Ground Effect NZ
Chain Reaction Cycles CRC UK
Wiggle Wiggle UK
Ebay Ebay AU

“Bicycles BNA Twitter
“Bicycles BNA Facebook
“Google+ BNA Google+
“Bicycles BNA Newsletter

> FREE BNA Stickers
> BNA Cycling Kit