Strava power estimate

fat_tail
fat_tail Posts: 786
edited November 2013 in Commuting chat
Hi

Just wondering if anyone has any insight into how Strava computes its power ? For example, this AM my power per Strava is 196W. On another ride where I have felt that I was working harder, the Strava power was 159W. This ride was longer than the first but average speed was roughly the same.
Ridley Fenix SL

Comments

  • fossyant
    fossyant Posts: 2,549
    Don't get worked up by it. Just ignore it, it's rubbish.
  • UndercoverElephant
    UndercoverElephant Posts: 5,796
    fat_tail wrote:
    Hi

    Just wondering if anyone has any insight into how Strava computes its power ? For example, this AM my power per Strava is 196W. On another ride where I have felt that I was working harder, the Strava power was 159W. This ride was longer than the first but average speed was roughly the same.

    On the other ride, was there a headwind? Strava can take no account of how hard you're actually having to work.
    Sun - Rain - Snow
  • fat_tail
    fat_tail Posts: 786
    UndercoverElephant wrote:
    fat_tail wrote:
    Hi

    Just wondering if anyone has any insight into how Strava computes its power ? For example, this AM my power per Strava is 196W. On another ride where I have felt that I was working harder, the Strava power was 159W. This ride was longer than the first but average speed was roughly the same.

    On the other ride, was there a headwind? Strava can take no account of how hard you're actually having to work.


    no - both rides in the same direction with a SW wind.
    Ridley Fenix SL
  • slowbike
    slowbike Posts: 8,498
    https://strava.zendesk.com/entries/2095 ... lculations
  • fat_tail
    fat_tail Posts: 786
    Slowbike wrote:
    https://strava.zendesk.com/entries/20959332-Power-Calculations


    I have seen that page before and I am also an engineer (ex). I was just wondering why it is that power reading for todays ride was so high. I have compared Strava power estimates to other calculators and they same to agree (except for today's !)
    Ridley Fenix SL
  • memsley89
    memsley89 Posts: 247
    watts can be inconsistent include strong winds and bad elevation data reported by the Garmin

    Your elevation data might be naff...
    Facebook
    Instagram
  • mtb-idle
    mtb-idle Posts: 2,179
    are you using an HRM?
    FCN = 4
  • fat_tail
    fat_tail Posts: 786
    MTB-Idle wrote:
    are you using an HRM?
    no .. just a strava app on an android phone.

    I suspect that the power estimate for today's ride is off... for some reason.
    Ridley Fenix SL
  • sketchley
    sketchley Posts: 4,238
    Strava once had me at 2000 watts round the elephant and castle...... I wouldn't read too much into it.....
    --
    Chris

    Genesis Equilibrium - FCN 3/4/5
  • meanredspider
    meanredspider Posts: 12,337
    fat_tail wrote:
    MTB-Idle wrote:
    are you using an HRM?
    no .. just a strava app on an android phone.

    I suspect that the power estimate for today's ride is off... for some reason.

    There, I suspect, is the root of the discrepancy - phones are really ropey - especially elevation. And because power squares with speed, if there are some spikes in the data, that will affect the average. Compare the two power plots.
    ROAD < Scott Foil HMX Di2, Volagi Liscio Di2, Jamis Renegade Elite Di2, Cube Reaction Race > ROUGH
  • fat_tail
    fat_tail Posts: 786
    meanredspider wrote:
    fat_tail wrote:
    MTB-Idle wrote:
    are you using an HRM?
    no .. just a strava app on an android phone.

    I suspect that the power estimate for today's ride is off... for some reason.

    There, I suspect, is the root of the discrepancy - phones are really ropey - especially elevation. And because power squares with speed, if there are some spikes in the data, that will affect the average. Compare the two power plots.

    This morning's ride is another example - average power is 170 W as per Strava. I suspect this has been affected by two outliers of 551W and 520W
    Ridley Fenix SL
  • bigmat
    bigmat Posts: 5,134
    fat_tail wrote:
    meanredspider wrote:
    fat_tail wrote:
    MTB-Idle wrote:
    are you using an HRM?
    no .. just a strava app on an android phone.

    I suspect that the power estimate for today's ride is off... for some reason.

    There, I suspect, is the root of the discrepancy - phones are really ropey - especially elevation. And because power squares with speed, if there are some spikes in the data, that will affect the average. Compare the two power plots.

    This morning's ride is another example - average power is 170 W as per Strava. I suspect this has been affected by two outliers of 551W and 520W

    550W sounds like a realistic power output - just done a peak power test at the gym and hit 1711W (admittedly held that for maybe 1RPM!) so I reckon I probably hit around 1000W from time to time on the commute.
    http://www.flickr.com/photos/41991871@N ... otostream/
  • Clever Pun
    Clever Pun Posts: 6,778
    Not strictly related but Fitness First were doing a challenge on the Watt Bikes at a set resistance... peaked at 1235W... not too bad
    Purveyor of sonic doom

    Very Hairy Roadie - FCN 4
    Fixed Pista- FCN 5
    Beared Bromptonite - FCN 14

Categories