GOTOES Strava Tools Forum

I have a file of time stamps that I wish to modify but have spent more than 1.5 hours trying various settings but none provide the time change I desire. The activity start time of my first entry is 2025-03-10 01:46:41 and I want to change it to 2025-03-10 14:46:41. Below are examples of 10 settings and their respective results.
What setting shall I choose to produce the desired first entry of 2025-03-10 14:46:41?

Pacific/Kanton +13 +13:00 2025-03-09 08:46:41
UTC 2025-03-09 09:21:41
Pacific/Wake +12 2025-03-09 09:46:41
Asia/Tokyo +9 2025-03-09 12:46:41
Asia +06 2025-03-09 15:46:41
Pacific/Kiritim 14+14 2025-03-09 07:46:41
America NY -4:00 2025-03-10 01:46:41
Pacific Midway -11:00 2025-03-10 08:46:41
America Adak -9:0 2025-03-10 06:46:41
America Nuuk -1:0 2025-03-09 23:46:41

Just to clarify, the "Time Zone" drop down on GOTOES is only relevant for a couple things. ALL GPS files are encoded using timestamps that are in the UTC time zone (the time at the Prime Meridian). So, when you select a time zone in GOTOES, the primary purpose of that is to display the time stamps on your screen (on GOTOES) in the same time zone that you're familiar with. When GOTOES generates the file, the timestamps will still be in the UTC time zone.

What ends up happening is that the platform you upload the files to (Strava/Garmin/etc) looks at the GPS coordinates of the activity, and then determines the time zone. Next, they take the UTC time from your GPS file, and translate it to the timezone determined by the coordinates of the file. If the workout was performed indoors, they do not know the locations, so Garmin and Strava will use the location set in your profile and translate the time from UTC to the time in that zone. This applies to GPX and TCX files.

Having said all of that GOTOES can and DOES specify a time-zone-offset in FIT File exports. In a FIT file, we still store all of the timestamps in UTC, however we also include the timezone offset, which helps - especially if the workout was indoors.

My advice for your situation, however, is to NOT CHANGE the time zone. Instead, specify the start time that you want (using the date picker). If you don't know the timezone of your file, click the "(reset)" link and GOTOES Will figure out the time zone for you. IF it is an indoor workout, GOTOES will choose UTC. Regardless of what you choose, fiddling with the time zone isn't the best way to go about this. Specifying the precise start time without manipulating time zone is going to be the best option.

If this does not help, upload your files to the forum, and let us know which platform you are viewing on (Strava, Garmin, etc). Also, you can specify if it is an indoor or outdoor workout (though I will likely be able to figure that out from the file if the source file is FIT).

Hello Fulmar2,
First of all I want to thank you for the very prompt and thorough reply to my question.

I just tried your suggestion, not specifying a time zone offset and simply entering the Activity Start Time using the date picker, 2025-03-10 01:46:41, and enabling "Time Shift" but the results were still incorrect in that the resulting file begins 2025-03-09 12:46:41 instead of the desired 2025-03-10 14:46:41.

Allow me to provide background as perhaps it will help. This GPX file was created using the "Ride with GPS" app on my iPhone 16 while I was traveling in Japan. I did not change any settings on that app as it is normally used in the Eastern time zone of USA. After creating 35 GPX files and downloading them to my PC and reading them with my PC's software, ExpertGPS, I realized that the date/time stamps were out of synch with the Japanese location so I was hoping your software would be able to correct the date time stamps before I permanently store the GPX files onto my computer. If it is helpful to you I can go ahead and upload one of the GPX files to you but I was hoping to not trouble you further.
Thanks, Lee