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  1. #1
    the half breed devil
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    how accurate is strava?

    in terms of the speeds it records on a ride?



    here you will see that strava has recorded my top speed at 49.0 mph, which i think is closer to 44-45 mph. in addition, the performance graph only shows a maximum speed of 32 point something mph.

    can anybody share informed insights as to how this all works?
    Attached Thumbnails Attached Thumbnails how accurate is strava?-picture-1.jpg  


  2. #2
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    What was your recording interval and why do you think you went the speed you think you went?

  3. #3
    the half breed devil
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    i just don't think i was going almost fifty. i braked to soon past my normal braking spot where i attain my daily high speed. recording interval? what's that?

    yesterday the speed/power/elevation graph wasn't completely correct because it might have taken strava a bit to process and fine tune the data.

    you're a good man, nate...you always chime in on these...

  4. #4
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    I did the EXACT same ride 2 weekends in a row and my distance was different by
    .4mi???

  5. #5
    the half breed devil
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    Quote Originally Posted by Silverwulf View Post
    I did the EXACT same ride 2 weekends in a row and my distance was different by
    .4mi???
    yeah, but our side jaunts which might not reflect on the map my be the difference there...

  6. #6
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    I use strave myself. I believe in terms of top speed there are certainly some times that it over estimates. I believe this to be instances in which the gps signal goes funky. I've recorded top speeds of mid 50's before on rides that I barely got over 40 (if that). I've done over 50mph before, and its a pretty unforgettable feeling. Anyway, in other terms I think it is as accurate as any gps based unit on the market. I show distance variances on the same route as well, but again - sometimes the gps signal gets screwy and other times it stays steady (based on the mapping of the ride). My regular computer is slightly more accurate regarding the mileage, speed, etc... but Strava is usually pretty close.
    P=DAL, P=DAL, P=DAL!

  7. #7
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    I don't think it's Strava that's the problem, but more likely the device that's doing the GPS calculations. I've uploaded past rides from a Garmin GPS I had and compared them to my most recent rides using an iPhone. Same trail, and the Garmin was way more consistent where as my iPhone would vary by .2 of mile on the same 3 mile stretch.

  8. #8
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    Yeah.....I'm using an iphone4. I plan on getting a garmin edge 500 in the next few weeks. Maybe that will help with consistency. I was on my roadbike and hit 80kph. And I was riding the brakes. I'm pretty sure that was accurate though. As one poster said, it's an unforgettable feeling!

  9. #9
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    Here's some data that I have from a ride that I tracked with iPhone 4S Strava app & Garmin Forerunner 410. You can see some slight differences.

    Device Garmin Forerunner 410
    Time 01:16:11
    Distance 21.0mi
    Elapsed Time 01:16:11
    Max Speed 24.4mph
    Avg Speed 16.6mph
    Cadence N/A
    Bike Redline D440

    Device Strava iPhone App
    Time 01:17:22
    Distance 21.2mi
    Elapsed Time 01:48:49 (i forgot to stop the app after the ride for a bit)
    Max Speed 26.5mph
    Avg Speed 16.4mph
    Cadence N/A
    Bike Redline D440

  10. #10
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    We're you recording the same ride simultaneously?

  11. #11
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    Since you're using a phone app it's important to know how they work. Phone gps hardware is not as good as dedicated hardware. To lessen the gap, good apps (like strava) "massage" the data and do heavy processing to close the gap...but there is still a gap which will vary from phone ro phone. Unfortunately phone mfrs do not say any more about which gps hardware they use so it's very hard to compare head-to-head.

    That will result in the occasional inaccuracy and variability in measurements.

    Recording interval is the frequency a position is recorded. All dedicated receivers and some apps let you specify this. If your recording interval is too long and your apeed changes during that interval then you have inaccuracies. Also a simgle errant point can result in an outlier speed. All sorts of thing can be the problem

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