Data of Intervals are very different from Strava Laps

[Tito]

Hi David!

I have just uploaded an activity from garmin to strava today 27Aug2020. But if I choose the option to use Laps instead of detected intervals, data for those intervals is very different from data on Strava or Garmin.

Intervals on Strava:

Intervals on Intervals.icu

For instance, Real Avg Power on intervals.icu es more than 10w lower for the same lap on Strava.

For me, it looks like Laps are not being detected at the same time or point as the laps in Strava, First Lap in Intervals is 26 minutes long, first interval in Intervals is 30 min long.

Please, check 6 minutes and 2 minutes intervals of the activity and detail the differences. Is there some thing am I doing wrong?

Link of activity:

https://intervals.icu/activities/3973381498

Thanks a lot!

Fabian

[david]

Tx. I re-analysed the activity using “Analyse” and ticked both boxes. This will use exactly the laps from Strava and keep all of them. The “Use laps” button still gets rid of very short, spurious laps.

Intervals.icu laps:

Strava data:

"laps": [
  {
    "name": "Lap 1",
    "distance": 7267.91,
    "end_index": 984,
    "lap_index": 1,
    "moving_time": 1241,
    "start_index": 0,
    "device_watts": true,
    "elapsed_time": 1605,
    "average_watts": 121.3,
    "start_date_local": "2020-08-27T05:04:57Z",
    "total_elevation_gain": 110.0
  },

Looking at the first interval the start and end indexes match the Strava data but the time (22m26s vs 26:45), distance (6.4km vs 7.26km) are very different. Intervals.icu uses the activity stream data to work this out (you can download the ride CSV to see these):

So row 2 is index 0, row 3 index 1 and so on in the data file. So Intervals.icu is using the 1346 seconds time (22m26s) for time but this is very different to the elapsed_time of 1605 in the Strava lap data. Likewise the distance (6.4km) matches the 6410m from the stream data but Strava has 7267m. The difference in time will throw out the average power calculations.

Total work done on that first interval is 112 kJ so the Intervals.icu “real avg power” of 83w is correct (112000 / 1346s).

I don’t know why the Strava lap data should be so different to the activity stream data. Intervals.icu needs to work off the activity stream data because as soon as you start making edits to intervals thats all there is.

Maybe Strava is using lap data “as is” from your Garmin and that is different? Still I don’t know why that should be the case.

So the intervals are different, I can’t tell where Strava’s numbers come from because they don’t match the activity stream data but it looks like Intervals.icu is correct according to the activity stream data.

[Tito]

Thanks for your support David!

Strava is showing laps data in very similar way to Garmin Laps, not exactly the same.

It is weird for me because Garmin and WKO5 (synced from TrainingPeaks) shows similar power numbers for the whole 34 laps as Strava with some little differences:

Garmin:

WKO5: (TraininkPeaks received activity from Garmin)

So, according with your answer, Strava is sending different stream data that it shows in their web right? If yes, How do you think can I force strava to send the stream data correctly?

I am going to try to upload file from garmin to strava manually (deleting the old one before) and then syncing again with intervals,icu.

[Tito]

Hi @david, my issue with laps continues with all my activities uploaded from Garmin to Strava and then to Intervals.icu.

Checking the streams csv file and comparing with Strava Laps, I can see 3 things:

1. There are no rows or indexes in the streams file when I stop my ride for most seconds elapsed stopped.

2. Start and End Index does not match the time or seconds in the fit file (Garmin and Strava have very similar laps)

3. Cannot see in streams file, a mark or index when laps begin and end.

Could you please let me know how Strava gives to intervals.icu the begin and end index or time for each lap?

Can we see somewhere the “laps” info as you show?

“laps”: [
{
“name”: “Lap 1”,
“distance”: 7267.91,
“end_index”: 984,
“lap_index”: 1,
“moving_time”: 1241,
“start_index”: 0,
“device_watts”: true,
“elapsed_time”: 1605,
“average_watts”: 121.3,
“start_date_local”: “2020-08-27T05:04:57Z”,
“total_elevation_gain”: 110.0
},

Thanks in Advance!!!

[david]

I have just sent you all the data I get from Strava in a message. I think this will probably only get resolved when I implement manual file upload and Garmin connect download so I have the .fit file to analyse. I am going to have to make Intervals.icu independent from Strava soon.

[Tito]

Wow!!! That sounds great! @david

I understand, I will wait anxiously

Thanks for your good support as always.

[Christophe_BOUYSSOU]

Golden cheetah has the same problem when datas are synchronized with Strava. But When Golden cheetah uses garmin connect to import datas, they’re the same! So synchronization with garmin connect seems to be the best way!