Normalize Date/Time issues For Strava


(Ernest Ezis) #1

Please fix the date and timestamp issue for Strava uploads. Mileage for rides that happen on Sunday should show up on Sunday . . . not Monday.  If there are complications with group rides and “races” – then give those of us that rely on weekly training data an option to fix the date and time issue when we upload to Strava.


(Eric C. (Zwift HQ)) #2

Hi Ernest,

From our “Commonly Asked Zwift Questions” stickied post:

STRAVA TIME STAMPS AND WEEKLY MILES

Since “Watopia” currently takes place on, very real, Te Anau Island in the Solomon Islands, your ride time stamps will reflect this physical location (UTC+11). Will this change? Maybe but not for now as we treat this ride as a real ride and not a trainer ride.

This also means that, for a lot of us, the rides will happen “in the future” and your miles may not show up in Strava until the next day.

 

You can find more answers to other commonly asked questions here: https://support.zwift.com/hc/communities/public/posts/202207149-Common-Zwift-Questions-and-Info

Thanks!


(Eric C. (Zwift HQ)) #3

For the record, we time-stamp your FIT file with GMT time. Strava takes those GPS coordinates and changes the time-stamp to reflect that.


(Ernest Ezis) #4

@Eric C, I believe there is some missing information in your explanation.  

That you time-stamp the FIT file with our local time seems to be immaterial. I used the “Time Adjustor” on this site – https://www.fitfiletools.com/#/top – to take my ride from Sunday and “push it back in time” to Saturday. So now, on Strava, my Sunday ride happens “before” my Saturday ride, but my weekly mileage is now correct. The time-stamp on the “fixed” file is “today, 6:04 PM” (where today is 4/27).  So it would seem that Strava’s adjustments are independent of the file’s time-stamp, because I was able to place my ride where I wanted it even though the FIT file’s time-stamp is two days+ after the ride.

If the time-stamp is immaterial, then something else is happening, so please allow me two clarifying questions:

Do FIT files have a <time> field like GPX files?  

If so, does Strava use those values directly, without adjustment?

If the answers are “Yes”, and “Yes”, then clearly the <time> field could be adjusted in the FIT file before it was uploaded to Strava.  

If either answer is “No” can you please elaborate on what happens instead.  

Thanks.

 


(Don Barnard) #5

What is the right time stamp? If you localize the time, people who rode together won’t show up as having rode together on Strava, so you’re going to lose something either way unless Strava makes zwift a special case.


(Ernest Ezis) #6

@Don, that’s very easy, make it conditional.  That is not an issue.  


(Eric C. (Zwift HQ)) #7

Strava thinks you are actually riding on Tu Anau. It will take those GPS coordinates and apply the correct time stamp for that time zone. It does not matter what time stamp *we* apply currently.

Unless there is an exception in the case of Zwift or you mark your ride as a trainer ride, this is the reality of the situation for now.

 


(Ernest Ezis) #8

@Eric, if Strava gets at GPX file instead of a FIT file for the ride, do they accept the <time> data fields “as is” in the GPX file or do they still try to apply the “correct” time stamp for that time zone?  

I understand Zwift’s position, but I can code and if there is something in the process flow that I can exploit to write my own solution, I will probably do so. But I only know what you can tell me, which is why I asked the specific questions above. 


(Eric C. (Zwift HQ)) #9

That is something you will have to take up with Strava. It confused us the first time it happened.


(Eric C. (Zwift HQ)) #10

So hey, one of our other Beta Riders found a way to change your FIT file time-stamps but you’ll miss out on being tagged with other riders:

http://www.johnstonefitness.com/2015/04/29/clearing-up-the-zwiftstrava-timestamp-confusion-with-solution/

An interim solution until something is figured out for a very unique case.


(Steven Riley) #11

Strava need to have a timezone setting for weekly miles. It took the calendar apps years to fix this. Don’t hold your breath.


(Philip Amos) #12

Having rides show up in Strava in the future is annoying.  I live in the UK and I wasn’t really affected before the new island because the old island was in the past and I rode in the evening so rides still showed up on same day.

I have examined the FIT file and I can see that you time stamp with my local time and that when this is uploaded to Strava they look at the “real timezone” that the ride took place in and then automatically adjust the time.

What you could do is have an option within Zwift whereby people can choose to have the time you write to the FIT file off set so that when Strava then adds time to it the ride will show up as the time it was actually ridden an not the local island time.


(Eric C. (Zwift HQ)) #13

Hi Philip,

Strava doesn’t add time as far as I can tell - it replaces it with the “correct” time.


(Philip Amos) #14

Strava has to be adding or subtracting time other how does it replace it??  Otherwise how would you explain the swing in the other direction now you have moved the island from behind GMT to ahead of GMT.

i would guess that you are writing Utc time to the Fit file.  You can’t be writing local time because if I ride with people in Ny (-5 hours to me) then Strava wouldn’t match us as having ridden together so the time in the Fit file has to be the same for me and the Ny people.

what Strava and other sites are doing is taking the Fit files (for any device) and then looking at the Utc time and adjusting it by either adding or subtracting time based on the local time zone of the Gps coordinates repeating to UTC/GMT to get the correct local time.

check with the developers and I’m sure they will confirm they are writing either GMT or UTC time.


(Philip Amos) #15

I should have also mentioned that if I upload your FIT file to Garmin Connect and then export as a TCX file which is human readable you will notice that there is no mention of a time zone, it just has a time listed.

Then if I upload this TCX to Strava it will adjust the time to local Island time.  So it must be adding the time zones based on the coordinates of where the island is.  The reverse was true on old island as it subtracted time to get correct local time.

What people want is the option to choose what time you write to the Fit file as you could easily  subtract say 10 hours for UK people and what ever the off set is for other countries so instead of writing 14:00 which would be the correct time you would write 4:00 and then when Strava corrects the time the ride will end up as 14:00.


(Brandon Amos) #16

If you find you manually delete upload the Zwift FIT file into Strava there is a point when it reads the data and before it calculates everything and lets your finalise the upload.  At the start of the upload, Strava shows the date/time of the ride as being the time you road it in your local time zone.  Then after it has finished computing everything and lets you finalise the update it updates the time that is displayed to screen, this is because the time in the FIT file does not include a timezone and Strava quite rightly converts it to local time of the ride.

I have written a program that takes the Zwift zip file and updates the following parts of the FIT file.  As I live in the UK the update is to remove 10 * 3600 from each value.

FileIdMesg.TimeCreated

EventMesg.Timestamp

DeviceInfoMesg.Timestamp

TrainingFileMesg.Timestamp

TrainingFileMesg.TimeCreated

RecordMesg.Timestamp

LapMesg.Timestamp

LapMesg.StartTime

SessionMesg.Timestamp

SessionMesg.StartTime

ActivityMesg.Timestamp