Strava - Riding with other people

[rstrom]

I recently discovered that Strava was no longer grouping me with people that I've been riding with (a function that has definitely worked in the past). I submitted a ticket with the folks @ Strava (see below)

Here's my original ticket -

Whenever I used to ride with a group of people Strava used to say Robert Strom (and 5 other riders). I rode a ride today with another rider and Strava does not say or seem to recognize that we did this ride together.

This was a nice feature that seems to be gone now.

What happened to this feature / function?

Can you please bring it back?

Thanks,

Robert

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

The first response

Hi Robert,

We recently made some changes to our algorithm for "group activities". We made it so that you need to have at least 50% of your segments in common with the other user (sensitive to WHEN you completed the segments as well) in order for the group activity to be detected.

Could that be at play here?

Best,
Strava Support Team

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

I went on to cite examples of a 100 mile ride where I was there the entire time and others were there for only 45 or 60 miles of the ride and they were grouped and I was not.

Here is the response

Hi Robert - I've figured out the issue:

You happen to be using iBike - and uploading CSV files to Strava.
The format for the timestamps in the CSV are in local time - and Strava expects Zulu/UTC at all times.

Here's an example: For your ride on the 13th, your first timestamp is as follows:
2012-12-13T16:15:26

Your rides started at around 4:15, correct?

In technical terms, the timezone in this format is specified by the letter "Z" at the end of the timestamp to signify "Zulu" or UTC time. When Strava does not see the Z it assumes local time in San Francisco (could be considered a bug - and is certainly egocentric). Strava then converts all timestamps to Zulu or GMT by adding 8 hours (current timezone correction for San Francisco to GMT). Then Strava puts the time in your local timezone, which is Phoenix, by subtracting 7 hours.

So, you've just lost an hour!

If you look on your activity page, your time is listed as starting at 5:14, not 4:15. therefore, Strava doesn't see that you rode with Michael, as his timezones are correct!

Now, your next question will likely be...how can this be fixed?

Answer - I don't know. But I'll see what I can find out.

Best,
Strava Support Team

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I then looked back at some previous rides and found some where I was grouped with other riders and the start time was correct. I also looked at the associated iBike files and they do not appear to be any different.

Do you have any insight into this?

Can you please work with the folks @ Strava to try and get this solved?

Is there a way that you could give us a choice of exporting the CSV file and have it log Zulu/UTC time?

Thanks,

Robert

[racerfern]

BINGO! I think the reason some activities are grouped properly and some are not may be due to the differences between Daylight Savings and Standard Time.

This has been an issue for some time with iBike thinking Strava was doing something wrong and vice versa. It's not a matter of anyone doing anything wrong it's just a matter of everybody being on the same page.

In your discussion with Strava please see if going being in DST or not could be causing the issue since people with Garmin units will automatically adjust to "Z" time.

[texmurphy]

For a little test I compared a Strava Garmin 500 .fit upload to iBike exported .csv and .tcx uploads. Note the .fit was merged by Isaac with my Newton iBike data. The .fit start time reflects starting the Garmin before the Newton. I normally upload only Garmin to Strava.
Edge 500 .fit - started @ 9:30am with Distance=54.5mi Elevation=3,486ft MovingTime=03:21:37

iBike tcx - started @ 9:34am with Distance=54.5mi Elevation=4,294ft MovingTime=03:22:17

iBike csv - started @ 12:34pm with Distance=54.5mi Elevation=4,115ft MovingTime=03:21:42

Strava clearly will not associate iBike .csv uploads with .tcx or .fit uploads for grouped riders. So you should export .tcx for Strava upload.

other notes:
- due to sampling of gps trackpoints, the iBike merge gave me a one second advantage over the Garmin .fit for a PR on a Segment in both the .tcx and .csv
- clearly some difference in elevation and moving time calculations in Strava between tcx and csv processing.

[racerfern]

But if you merge in Isaac you can export to TCX but the time will still be off. No?

[texmurphy]

But if you merge in Isaac you can export to TCX but the time will still be off. No?

The above test was done using Isaac merged with .fit exports.
Issac outputs a Z format in the tcx <Id>2012-12-12T14:34:22Z</Id>
Isaac merged timestamps in the csv are local time 2012-12-12T09:34:18

[rstrom]

Yes, you're correct about the DST (Arizona has none)

Here is the latest response from Strava

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Dec 17 01:55 pm (PST):
Hi Robert - I think I know the answer.

Arizona doesn't do Daylight Savings Time, right?

So half the year you are in the same timezone as San Francisco, and the other half you are an hour off....

Sorry again for the trouble - we should get this fixed.

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So, it sounds like they are going to fix it but I was thinking that maybe iBike could create an option in the software where you could specify that your CSV file was exported using UTC/Zulu time. You'd need to add time zone functionality to the program as well as that feature/function. That would / should solve the problem forever.

Robert

[racerfern]

So, it sounds like they are going to fix it but I was thinking that maybe iBike could create an option in the software where you could specify that your CSV file was exported using UTC/Zulu time. You'd need to add time zone functionality to the program as well as that feature/function. That would / should solve the problem forever.

+1

[rstrom]

Fernando,

So we both agree that this should be a feature / function.

Do you know what needs to be done to get this on the list?

Thanks,

Robert

[racerfern]

I'm fortunate to be a beta tester and I can assure you it's on the list.

[rstrom]

Excellent!

Thanks much Fernando!

[texmurphy]

Isaac for Windows Version 1.0.10
* Created a new version of the CSV export format, version 13. Changes have been made in such a way that 3rd-party importers that can read version 12 should continue to work without modification. However, there is additional information available in the new version. Some highlights of the new format: 1) Timestamps are written in universal time (UTC) rather than local time; 2) all of the encoded information has been removed from the header and records; 3) labels have been added to the header information; and 4) columns have been added for riding time, CdA as calculated with a DFPM, and air density.
* Updated Newton Instructions.
* Fixed a bug with showing ride file names in the power meter comparison window.
* Fixed a bug affecting some of the analysis functions for ride files recorded at 5 s recording rat

Out of interest I exported a csv and a tcx to compare exported data since this is of interest for Strava uploads, etc.
This from an Edge 500 merged .fit with Newton+ data by Isaac.
The tcx outputs gps coordinates with 6 digit significance vs the csv with it rounded to 5 digit significance (standard rounding rules - >=5 rounds up).
The tcx outputs ns3:speed as m/s, csv as mph so conversion is ns3:speed*3.6 to get kph converted to mph. ns3:speed is output 1 decimal point and result in csv speed is rounded to 1 decimal point as mph.
The tcx altitude for a selected point (see below) was 220.6 meters yet same point in the csv showed as 723.7048 ft (meters to feet should yield 723.753). This maybe because I did Analyze->Route correct ride to end where begun. Possible that tcx (or csv) used value before (after) the Analyze, but I think they should have both output the same value (post analyze).

So, not sure for those exporting from Isaac to Strava which format is superior in pursuit of KOM timing. In general 1-second recording will yield a superior Strava result over 5-second recording. On average at least a 2 second higher Strava score

Selected point from tcx and csv files shown below:

Code: Select all

     <Trackpoint>
      <Time>2012-12-24T15:08:47Z</Time>
      <Position>
       <LatitudeDegrees>39.464499</LatitudeDegrees>
       <LongitudeDegrees>-76.748868</LongitudeDegrees>
      </Position>
      <AltitudeMeters>220.6</AltitudeMeters>
      <DistanceMeters>19640.2</DistanceMeters>
      <HeartRateBpm>
       <Value>139</Value>
      </HeartRateBpm>
      <Cadence>79</Cadence>
      <Extensions>
       <ns3:TPX>
        <ns3:Speed>7.0</ns3:Speed>
        <ns3:Watts>311</ns3:Watts>
       </ns3:TPX>
      </Extensions>
     </Trackpoint>

Code: Select all

Speed (mph)	Wind Speed (mph)	Power (W)	Distance (miles)	Cadence (RPM)	Heartrate (BPM)	Elevation (feet)	Hill slope (%)	Temperature (degF)	Lap Marker	Annotation	DFPM Power	Latitude	Longitude	Timestamp

15.6000	13.9719	311.4487	12.2038	79	139	723.7048	3.5391	36			0	39.464500	-76.748870	2012-12-24T15:08:47Z

[rstrom]

Excellent ... I updated Issac. Looking forward to downloading my first ride into the software and seeing the correct time in Strava (without having to manually modify the file to hack the time stamp).

Happy Holidays!

Thanks much,

Robert

[rstrom]

It worked as advertized!

Excellente!

Thanks much,

Robert