Normalised Power for a sub section of a Ride

vosadrian
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Normalised Power for a sub section of a Ride

Postby vosadrian » Fri Feb 09, 2018 3:37 pm

Hi All,

I am not particularly (at all!!) serious about training, but I like to see how my riding is going, and one way may be to look at power meter data for a ride activity. One thing I do realise is often a fast pace-line ride with a cycle of high power on the front and recovery when out of the wind will feel harder then a ride with similar average power done solo at a constant level (and I do both regularly). So I realise that Normalised Power is one way to compensate for this effect.

I use a Garmin Edge 520 that I upload to Garmin Connect that pushes across to Strava. Both these platforms have a form of Normalised Power or equivalent, but it is a value given for the whole ride. Often my activities include a light ride to warm up or commute to the main event and same afterwards. I can easily determine average power for the main event using analysis on Strava to highlight the section of the ride. But I can't see a way to get NP for the main event part of the ride. I was just wondering if anyone here had found a simple and free way to do this. I am not looking to pay a subscription to a training service that offers this, as I don't need that. I am perfectly happy to just potter away at it myself... I just want a way to compare efforts of my rides. I realise I could split my rides into seperate activities for each part, but that is a pain to manage and I will forget to do it once out there. Prefer something that can be done easily afterwards. I could crop the ride, but I like to record the other bits also. Probably Garmin Connect can do it, but I just have not worked out how.

Cheers,

Adrian
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kb
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Re: Normalised Power for a sub section of a Ride

Postby kb » Fri Feb 09, 2018 4:52 pm

If you’re looking at a segment, http://thomaschampagne.github.io/stravistix/ will do it but not for a lap or arbitrary selection
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Alex Simmons/RST
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Re: Normalised Power for a sub section of a Ride

Postby Alex Simmons/RST » Fri Feb 09, 2018 8:35 pm

Desktop analysis software is probably the way to go for that.

For free you'd need Golden Cheetah. It'll provide both Normalized Power and XPower, the Phil Skiba version of NP.

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Re: Normalised Power for a sub section of a Ride

Postby vosadrian » Mon Feb 12, 2018 10:46 am

Thanks guys,

I run Stravistix, so checked that and found it can do a segment... so I can just create a segment for the section I am after. I also had a play with veloviewer which I also use. It can view activities and allows you to highlight a section of the ride, and it will show averages for all your data for that section. It turns out in the power section with the average it will also do NP, so that works also.

Thanks again for your help!
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kb
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Re: Normalised Power for a sub section of a Ride

Postby kb » Mon Feb 12, 2018 12:23 pm

Cool. Didn’t mention VV as you’d said no subscriptions :-). That said, I’d probably follow Alex’s suggestion of Golden Cheetah unless the idea of desktop software is too painful.
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Alex Simmons/RST
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Re: Normalised Power for a sub section of a Ride

Postby Alex Simmons/RST » Mon Feb 12, 2018 4:49 pm

Just keep in mind the limitations of NP - don't go looking at short duration segments and start thinking it tells you much about your equivalent quasi steady state metabolic capacity (it tells you something but it's more easily misinterpreted than I can be bothered to explain right now).

I'd stick with 30+ minutes as a minimum duration for NP segments (20-min at a pinch depending on what sort of rider you are / sort of ride you did).

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Re: Normalised Power for a sub section of a Ride

Postby vosadrian » Tue Feb 13, 2018 11:37 am

My initial hope was that I could use Strava or Connect to get the "segment" NP. Veloviewer is something I subscribe to as it is very cheap, and gives me great search engine capability into all my strava activities that Strava cannot provide. If I want to find my highest average power/average speed/average HR ride, it is very easy with veloviewer. I did not realise it did NP until the other day. I still can't see how to get it for a segment, but I can go to the activity->Data and highlight the section I am interested in.

My interest in NP was more to compare efforts solo to fast bunches. I typically do most of my rides solo, and will try to do a quasi TT once a week at near max 1 hour effort for me. I also tend to do one fast bunch 1 hour ride a week (near my limit), and I was interested to compare them. I think my FTP is about 280W (Predicted from Strava power graph), and the NP (VV) and weighted average (Stravistix) for the fast bunch for an hour was around 270W (245W average). That kind of all makes sense, as the bunch did ease off a couple times for a minute or two, so that would have reduced NP (and I think 280W NP is achievable), so the numbers kind of add up to where I think I am which is what I was after!

I'm not really training for anything. And my training is a loose term. Not much structure to it. Just a couple hard rides and several soft rides plus commuting a week. But I typically ease off over winter, so good to see how I am going this year at peak compared to last.

Cheers guys!
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Re: Normalised Power for a sub section of a Ride

Postby Alex Simmons/RST » Tue Feb 13, 2018 3:46 pm

NP from a hard hour of riding can be up to 5% higher than FTP. For very occasional freaks with a specific combination of physiological characteristics it may be higher.

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Re: Normalised Power for a sub section of a Ride

Postby vosadrian » Tue Feb 13, 2018 4:35 pm

Alex Simmons/RST wrote:NP from a hard hour of riding can be up to 5% higher than FTP. For very occasional freaks with a specific combination of physiological characteristics it may be higher.


I thought the idea of NP was meant to equate varying power to a constant average power (as would be used for FTP). Is the 5% higher because it does not do a great job of the approximation... or perhaps it is physiology dependant? I tend to be more of a punchy rider who can do short duration at high power but not great at sustained climbing. I guess that sort of physiology would do better on NP, so perhaps my FTP is less than I think. I am trying to avoid doing an actual FTP test... difficult to manage and sounds like pain. Climbs around me last about 10 mins, so that is my longer sustained efforts. I think Strava somehow estimates FTP from that.
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Re: Normalised Power for a sub section of a Ride

Postby Alex Simmons/RST » Tue Feb 13, 2018 6:15 pm

vosadrian wrote:
Alex Simmons/RST wrote:NP from a hard hour of riding can be up to 5% higher than FTP. For very occasional freaks with a specific combination of physiological characteristics it may be higher.


I thought the idea of NP was meant to equate varying power to a constant average power (as would be used for FTP). Is the 5% higher because it does not do a great job of the approximation... or perhaps it is physiology dependant? I tend to be more of a punchy rider who can do short duration at high power but not great at sustained climbing. I guess that sort of physiology would do better on NP, so perhaps my FTP is less than I think. I am trying to avoid doing an actual FTP test... difficult to manage and sounds like pain. Climbs around me last about 10 mins, so that is my longer sustained efforts. I think Strava somehow estimates FTP from that.

Some reading:
http://alex-cycle.blogspot.com.au/2008/ ... -sins.html

http://alex-cycle.blogspot.com.au/2013/ ... t-iii.html

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MichaelB
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Re: Normalised Power for a sub section of a Ride

Postby MichaelB » Thu Feb 15, 2018 1:45 pm

hiya,

Whilst my free trial of cycling analytics is about to expire, I had a quick look, and it seems that what you are after can be done here. I've posted a pic below showing the full ride, and how I've spilt a climb into time splits (of 1:00 each), but you can also do the splits into distance (I've done it for time), but as Alex mentioned, it may not be useful for any meaningful calc

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It shows a whol;e pile of metrics, including average power and Effective Power (I guess this is CA's version of Normalised power).

I almost stumped up for a year of CA (AT) A$80, but went for Training Peaks as it does just a few more bits that I like. Another luxury on top of a PM that I don't use properly, but hey, just got paid.

Oh, and on the ride this morning, set a new FTP of 300W :mrgreen:

vosadrian
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Re: Normalised Power for a sub section of a Ride

Postby vosadrian » Fri Feb 16, 2018 10:39 am

MichaelB wrote:Oh, and on the ride this morning, set a new FTP of 300W :mrgreen:


Congrats!!.... that is a number I would like to reach at some point. Something about round number thresholds that is satisfying!
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Re: Normalised Power for a sub section of a Ride

Postby g-boaf » Fri Feb 16, 2018 10:50 am

MichaelB wrote:Oh, and on the ride this morning, set a new FTP of 300W :mrgreen:


Bonus! :)

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Re: Normalised Power for a sub section of a Ride

Postby MichaelB » Fri Feb 16, 2018 1:22 pm

It was an interesting 'segment' to set it on, as the gradient isn't constant (less at bottom and steepens up to over 11%), but there is also a roundabout and a short flat section.

I'll take it though :mrgreen:

Now, to lose another 15kg ... :roll:

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