I recorded a cycle yesterday on my bike computer and uploaded it to strava when I was done and noticed the time is different on strava and power and speed. And I know other people it’s happening to. Which have different bike computer’s only thing we have the same is we pay for strava.
Strava only accounts for actual time not elapsed time. So if you stop at a stop light, sign or the café even if you hit stop it still only accounts for actual ride time.
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You have to look closely to see Elapsed Time:
My Garmin is set to always be recording, even when stopped.
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average and normalized power should be about the same, within a couple watts.
Watts is changed by 7. My question is why does strava change the data
Tadhg,
Will you screens shot what you are referring too?
I never look at Strava power numbers, but here is that same ride from yesterday on 3 different analysis tools:
| Analysis Tool | Average Power | Normalized Power |
|---|---|---|
| Garmin | 171W | 191W |
| TrainingPeaks | 171W | 190W |
| Strava | 178W | 188W |
With Strava seeing 4 minute difference between elapsed and moving duration.
And two days ago:
| Analysis Tool | Average Power | Normalized Power |
|---|---|---|
| Garmin | 183W | 219W |
| TrainingPeaks | 183W | 218W |
| Strava | 184W | 217W |
With Strava showing 30 second difference between moving and elapsed duration.
So based on those to data points, it seems that if you have a long stop, then Strava will use the shorter duration to calculate average power.
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I’ve never looked into it deeply but I think Strava autopauses at 0mph whereas Garmin is usually set to something like 4mph. Add that to rounding differences and things can be different. Power I believe is similar and also affected by the auto pause.
Observations I made many years ago:
- turn off auto-pause on your recording device
- Strava is best used for analyzing segment times
- don’t worry about small differences
- Strava segments under 30-60 seconds can have serious errors because of how Strava maps your GPS to the segment
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We call it “strava doping” because on some segments if you use the strava app to record a ride on your phone. You can get sometimes get up to a minute off the segment compared with someone who is using a garmin or wahoo head unit.
Not the same but I wonder if anyone else noticed this?
I am somewhat confused here, but according to whatever log you are using it states that it is a moving ratio of 89.7% with a average speed of 46.98. If you use proper rounding factors that is 47*.90= 42.3km/h.
The strava is capturing your actual moving speed/time or your moving ratio.
Do you use a speed magnet or GPS? I use the latter and Strava says things like 35-40mph when gps (IMC Garmin) only says 32mph 
I’m not really worried about the time differences more about the average speed being so different. And why is it so different if all strava is doing is putting the data from my bike computer onto strava so people can see it. It shouldn’t be changing data
Strava uses its own data algorithm capture to try and keep all post similar across all different types of work out capture devices (Garmin, Wahoo, Hammerhead, phone apps etc).
I’m using speed sensor as I’m in doors
@teddygram did the math for you…
- your app shows average speed of 46.98 km/h
- your app shows .897 moving ratio
- 46.98 x .897 = 42.1 km/h
- Strava shows 42.3 km/h
I think that is correct way to look at it, but I never look at Strava average speed or average power.
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Thanks for that 
definitely going to look more into it
using @teddygram math…
- elapsed duration roughly 120 minutes
- moving duration roughly 116 minutes
- 171 watts x (120 / 116) = 177 watts average power
- Strava shows 178 watts average power
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