Accurate Power Data For Strava Segments
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I would also set up the wahoo for Average power for your rides from the PM only and check it before you upload the ride
Then you'll know if 1 or both are out0 -
trevor.hall12 said:
Is your auto pause on ?ibr17xvii said:wavefront said:Strava seems to penalise you for stopping and not pedalling. It may be my style of riding but my numbers are pretty close to my real numbers from my PM (I use GC to analyse which turns out identical numbers to TP). On chain tight rides or TT’s - constant power rides where my AP and NP are very very similar or identical. Strava shows only a watt or two difference from GC. On rides which involve more variation, the numbers are different by up to about 8% on strava vs CG. (Saying that, did a 3hr hilly ride no stops apart from junctions at the weekend with a fair bit of downhill coasting, and my AP between Strava / GC were only 1 watt diff, and NP 10w difference)
Weather, wind direction etc makes no difference to the numbers, only that they may affect your riding style you may notice some differences , but you’re experiencing a big difference so I understand why you’re puzzled.
Go out and do a short (over 30mins to get NP to adjust properly) chain tight ride at a constant power with little or no stops. Have a look at TP and strava and see what they show - should be within a watt or two.
FWIW, I’m sure I have a free TP account and whilst all the analytics aren’t there, it’ll show you NP/AP for your ride to allow you to compare.
Out of interest what PM are you using?
Interesting. I have a 4iiii single sided PM.
That does make sense actually cos on my ride yesterday I mentioned above it was a hilly ride with close to 5000ft elevation that did have a fair bit of downhill & I also stopped twice so I guess that’s why Strava said it was a 154w average but TP much higher.
FWIW I’ve always thought the Strava estimate was ridiculously low on the averages even before I got the PM.
It’s not a dealbreaker & it’s certainly not ruining my life but I like to see my data on specific segments to try & track improvements over time. I always go off the average & NP on TP for the total ride anyway.
If the segments are pretty accurate then that’s good enough. I think you can narrow it down to a specific section / segment on TP but only on the premium version
I know it can mess with average speed ,not sure if it does the same with power
I do have auto pause on.
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trevor.hall12 said:
I would also set up the wahoo for Average power for your rides from the PM only and check it before you upload the ride
Then you'll know if 1 or both are out
Wahoo Elemnt app says for the ride today 163w average, NP 153w so pretty much the same as TP.
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kingstongraham said:
If the power number is coming from the PM in both cases, it's not PM vs Strava, it's TP vs Strava.ibr17xvii said:
No in all honesty! I suppose I’m presuming the PM is more accurate (which it should be) & how I’m feeling when riding.kingstongraham said:Are you sure it's Strava that's inaccurate?
Ride today: easy spin, no stops apart from traffic lights, no elevation to speak of (240ft) just cruising basically - Strava average 136w, weighted 144w - TP average 163w NP 155.
Based on the numbers I was seeing on screen & how I was going 136w seems low to me, TP 163w seems about right.
“It’s a rabbit hole” as Shane Miller would say. Think I’ll just accept the differences & go with TP. Like I said it’s not ruining my life, I was just curious.
Normalised power should never be lower than average power though (for a whole ride assuming it's over 20 minutes), so something looks wrong there.
I do try & calibrate the PM before every ride but must admit I forgot today.
As has been proved throughout this thread I'm certainly no expert as I've not had the PM that long but I have had NP lower than average a few times before but not many. It's usually the other way round.0 -
Turn off the auto pause, and anything else that does averaging based on non zero power or records power at anything other than every second. Seems to me like it's TP that is overstating the average for some reason, I'm afraid.0
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kingstongraham said:
Turn off the auto pause, and anything else that does averaging based on non zero power or records power at anything other than every second. Seems to me like it's TP that is overstating the average for some reason, I'm afraid.
I have my Wahoo set not to include zeros on both cadence & power so if auto pause is on isn't that the same thing? i.e. there's no reading so it won't include it?
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If it's not including zeroes, then tp may be taking an average of the non-zero power. Strava will be an average of the power while moving which would be more correct. Surprised that tp would do that.ibr17xvii said:kingstongraham said:Turn off the auto pause, and anything else that does averaging based on non zero power or records power at anything other than every second. Seems to me like it's TP that is overstating the average for some reason, I'm afraid.
I have my Wahoo set not to include zeros on both cadence & power so if auto pause is on isn't that the same thing? i.e. there's no reading so it won't include it?
You'd want an average power to include zeroes while coasting.1 -
It is interesting to see your NP lower than AP, as KG has said, it’s almost always the other way around. I have a few 1-2 hr rides where the resultant NP was lower than AP but only by one or two watts - they were rides which were really consistent power with no spikes, just a billiard smooth power graph. The only other time you’ll see your NP lower than AP is for intervals that are shorter than around 20mins. So, if your total ride is shorter than that time frame you may see some strange skews, but usually average power will be the lower number. As an aside I’ll usually measure each of my intervals using AP, as an interval will be constant power, and as they’re often less than 20mins, AP will be the accurate number to follow.
Good to hear your numbers on Strava tally a bit better than you’d previously seen. Especially when the terrain or riding style is considered.
Finally, when you don’t see the word ‘weighted power’ on strava, that means the ride recorded no power, and it’s generated automatically by Strava from speed etc, and that number is always very random and means next to nothing.1 -
Thanks for all the replies, some really interesting stuff.
Still not sure I’m any closer to understanding if I’m honest. I think TP “should” be more accurate as the site is more of a training tool than Strava is so you would think they would have a better grip of the data but maybe it doesn’t work out like that.0 -
kingstongraham said:
If it's not including zeroes, then tp may be taking an average of the non-zero power. Strava will be an average of the power while moving which would be more correct. Surprised that tp would do that.ibr17xvii said:kingstongraham said:Turn off the auto pause, and anything else that does averaging based on non zero power or records power at anything other than every second. Seems to me like it's TP that is overstating the average for some reason, I'm afraid.
I have my Wahoo set not to include zeros on both cadence & power so if auto pause is on isn't that the same thing? i.e. there's no reading so it won't include it?
You'd want an average power to include zeroes while coasting.
I might try turning that on & switching auto pause off for a few rides to see what that does to the numbers.0 -
For power data you really need auto pause of and zeros included. Otherwise metrics based on power are skewed by the missing data.1
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wongataa said:
For power data you really need auto pause of and zeros included. Otherwise metrics based on power are skewed by the missing data.
Never heard that before.
I’ll try switching it off for a few rides & see how that compares.
Did a few intervals today & the lap averages were broadly similar from Wahoo & Strava. TP won’t let you see averages on laps without being Premium which is a bit annoying.0 -
I don't have a power meter but was forced onto my Neo 2T by a thunderstorm tonight. Don't know if it will be relevant or interesting but the Strava average and maximum power reflects the in-ride data. Not sure what the weighted figure is about.
The above may be fact, or fiction, I may be serious, I may be jesting.
I am not sure. You have no chance.Veronese68 wrote:PB is the most sensible person on here.1 -
The weighted power is Strava's version of Normalised Power. They don't use Normalised Power as it is a Coggan formula and they don't want to pay to use it. The number is a little different than NP for the same ride.1
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Thanks.wongataa said:The weighted power is Strava's version of Normalised Power. They don't use Normalised Power as it is a Coggan formula and they don't want to pay to use it. The number is a little different than NP for the same ride.
Not that I'm fussed. Completing a ride is success for me. 😉The above may be fact, or fiction, I may be serious, I may be jesting.
I am not sure. You have no chance.Veronese68 wrote:PB is the most sensible person on here.1 -
For OP's question about average power on a particular segment - if you're using a PM, the Strava reported value for the segment is (or should be) literally the average (not normalised) power over that segment directly from the powermeter (=from the Wahoo head unit in this case). Example screenshot, go to analysis in browser:
The way the programs account for stopped time is different. The Strava number is usually pretty close/identical for constant pedalling rides (=turbo workouts) for me.wongataa said:The weighted power is Strava's version of Normalised Power. They don't use Normalised Power as it is a Coggan formula and they don't want to pay to use it. The number is a little different than NP for the same ride.
Example from a recent outside ride I did:
Garmin 121
Intervals.icu 116
Strava 111
TrainerRoad 120
For an indoor workout with no coasting or stopped time, the 4 numbers are either identical or within 1 or 2 TSS (assuming I have remembered to keep the FTP up to date across all 4...). I queried the Intervals number as the guy who runs it is pretty approachable; he excludes stopped time (but not moving coasting time) from the TSS calc whereas Garmin/TR don't seem to. No idea what Strava does, possibly it removes coasting time too.
Example from my lunch turbo ride today (a 45 min TrainerRoad one, not recorded to Garmin on this one):
Intervals.icu 38
Strava 38
TrainerRoad 38
So the differences you see between NP (and therefore TSS) between platforms seems to be largely down to how the platform accounts for stopped and coasting time.
One other issue I have had with Strava which I've raised several support tickets about is it keeps inserting new FTP figures on random days, for no discernable reason. Which obviously throws everything off.1 -
Thanks @bobmcstuff that's really interesting.
I suppose when you're uploading rides to multiple platforms the way they interpret the data will be different. I guess I just presumed TP will be more accurate as it's marketed as a training platform whereas Strava isn't really. That's why I was asking about Strava segments particularly.
I've learnt a lot from everyone's replies though which has been great. I'm still getting to grips with PM's & structured training etc as it's not something I've ever done before.1 -
sure. power meter, best and most accurate way.ibr17xvii said:Is there any better way of getting accurate power data on Strava segments?.
how do you want to estimate bike weight, tire tread, tire pressure, bike drag (aero or not), your clothes drag (aero or loose/baggy), your position aero or upright ?
(the order was random)
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Read the thread.razorjack said:
sure. power meter, best and most accurate way.ibr17xvii said:Is there any better way of getting accurate power data on Strava segments?.
how do you want to estimate bike weight, tire tread, tire pressure, bike drag (aero or not), your clothes drag (aero or loose/baggy), your position aero or upright ?
(the order was random)0 -
Unless you have "Elevate" for strava installed on chrome, then it gives you the Coggan normalised power value.wongataa said:The weighted power is Strava's version of Normalised Power. They don't use Normalised Power as it is a Coggan formula and they don't want to pay to use it. The number is a little different than NP for the same ride.
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