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An Issue with merging and editing activities:

Mike-biker

"When I try to merge two activities in .fit format that were accidentally saved too early, I have to export them first. Even though I’ve tried GPX, TCX, and FIT formats, the resulting file shows nonsense time data and consequently incorrect average speed after importing.The same issue occurs when editing – specifically trimming an activity. On top of that, the changes don't sync back to my Garmin Edge Explore 2. Does anyone have a proven workaround or a reliable step-by-step method for this?"

  • 0

    What tool are you using to merge the activities? File Combiner can work occasionally, but not consistently. Fit File Repair Tool tends to be more reliable, though it requires a software license. Alternatively, you could zip the two files you want to merge and attach them to this thread, and we can try FFRT or other tools to combine them.

    Mike-biker said:
    the changes don't sync back to my Garmin Edge Explore 2

    Correct, they won’t unless you manually move the newly created activity into the \GARMIN\NewFiles folder on your Edge. That said, if you’re expecting this restored file to update performance metrics on the watch, it likely won’t, even if you can see the activity in your edge history.

  • 0 in reply to seilogramp
    I tried exporting the activities from the Garmin Connect web interface on my MacBook and merging them using File Combiner (Tools for Fit Files), as well as GPX Studio, Re-Track, Garmin BaseCamp, etc. It works, but the saved file always shows a nonsense time layout upon import—it factors in the total elapsed time, which tanks the average speed.
    I managed to restore the original records from my backup in Garmin Connect, where it shows 'Summary Data: Original', but I would like to know if it's possible to trim the route (edit the time data) and upload it back to Garmin Connect as an 'Original'?
    I am attaching a zip file with the two tracks to be merged. Thanks.3568.Archiv.zip
  • 0 in reply to Mike-biker

    Using FFRT to merge those 2 files I'm getting average speed of 19.1 kph. And shows as original after importing into Garmin Connect.

    2025-08-22-12-32-37-merged.fit

    I didn’t make any changes to the time data, just let FFRT handle it using the “Append Mode” option. Is that what you’d expect, or could it still be off somehow?

    As for trimming in Garmin Connect, those edits only affect how it’s displayed on the site. The original data remains unless you delete it and import a corrected or merged file from third-party tools.

    If you're concerned with elapsed time being wrong, that can be fixed also with FFRT.

  • 0 in reply to seilogramp
    Hi, thank you so much! There are a few minor details, but they aren't worth worrying about. The distance, time, and average speed all match perfectly.
    Unfortunately, I use a MacBook, so I only have access to online tools, not for FFRT. For connecting to my Garmin, I use OpenMTP, and I also have a paid subscription to Edit Edge Data for any minor adjustments.