UPDATE JUNE 13, 2025:
Since making this original post, I have created a second tool that you can use to shrink your FIT files. This tool eliminates some of your data, but it can take a 15MB file and reduce it to a strava-readable 1.5MB FIT file (or even smaller if you want). This tool is good for those times when you rode your bike across the continent without turning your GPS off - and saved it all in one big file! You will lose some of the granularity of your data, but at least you will be able to post it to Strava! I recommend that you try the CSV method first, and the FIT File Shrinker (tutorial) tool second.
- Make your FIT files smaller for better processing on GOTOES and Strava
ORIGINAL POST
The FIT file format allows for the storage of a massive amount of data in a relatively small file. Frankly, it's amazing how much information you can pack into such a small file. A problem arises when there is SO MUCH data in the file that ordinary tools can't handle all of the data points. Once a FIT file exceeds about 2.5Mb in size, it probably contains more information than standard approaches can handle. Today, for example, I was looking at a 5.4Mb file that had a quarter million time stamps. Each stream (power, heart rate, latitude, longitude, etc.) had its own set of 1/4 million points. Add that all up and you have several million points. On top of that, by recording HRV (Heart Rate Variability), you now have points recorded in-between-seconds. All together, it's too much to process.
To resolve this, I built the FIT -> CSV tool which extracts just the important data form the FIT file and ignores all of the extra "junk". Here is how to use that tool to get your files processed on GOTOES.
Step 1:
Upload your problem file to the FIT -> CSV tool.
- Upload your problem FIT file to the converter.
Step 2:
After the upload, download the converted file by clicking the big blue button:
- Download the converted FIT file that has been converted to CSV.
Step 3:
You will notice that the CSV file is MUCH bigger than the original FIT file. That is OK... The file is big because the data is not compressed. In reality, though, we have actually removed a lot of the "junk" data from the file. Often the CSV file is so big that you will need to compress it in order to re-upload. GOTOES has a 15Mb upload limit. You can shrink the CSV file for re-upload by zipping it. If you don't know how to zip a file, here are instructions. My screen shot below shows me making a ZIP file on my Mac by right-clicking on the GOTOES CSV file:
- Zipping a GOTOES CSV file to re-upload to the Merge Tool
Step 4:
Now that you have a smaller file, go back to the merge tool and give it another go with the zipped file. Often, even with enormous files with millions of points, GOTOES can handle processing within a few seconds. See screen shot below. This was a 5.4Mb FIT file that became a 42.7Mb CSV file (4Mb after I zipped it). Processing of the zipped CSV took 5 seconds, where as the FIT file times out after 180 seconds. Note how the tool tries to encourage you to reduce tracepoint density if you're going to export as FIT. This will make your file more "digestible" by apps like Strava. You can override that setting, but there is no guarantee that Strava will be able to handle it. Enjoy!
- Success! Processing a super big FIT file on GOTOES.