I had to go hunting for my garmin files a while back, and wrote a thread documenting it since the garmin docs were out of date. They're all .FIT files, but you could use golden cheetah to convert them if the website doesn't take FIT.

Might help you: http://forum.slowtwitch.com/...n%20connect;#5525690

Short version:
1) Go to c:\programdata\garmin\coreservice\devices on windows
2) Dig in the directories you find until you find one full of extensionless files
3) Rename them to .FIT, and upload them to wherever you want

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STAC Zero Trainer - Zero noise, zero tire contact, zero moving parts. Suffer in Silence starting fall 2016

FWIW my .tcx files from my 310XT end up here on my Mac:

/Users/mike/Library/Application Support/Garmin/Devices/3821097201/History


You will obviously have a different username and device ID but might be similar.

Are you using Garmin Express or Ant Agent?

For my 310 GE gives me FIT files and Ant Agent gives me TCX files

Garmin express.

For me on Windows 7 my Garmin Express FIT files are located
C:/ProgramData/Garmin/GarminConnect/Forerunner 310XT-38809XXXX/upload/FIT_TYPE_4

If you set up garmin connect, you can re-download the files in a variety of formats from garmin connect.

That said, my garmin connect experience is super-spotty, which is why I went hunting for the raw files.

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STAC Zero Trainer - Zero noise, zero tire contact, zero moving parts. Suffer in Silence starting fall 2016

My experience with downloading files from Garmin Connect is spotty too.

Any other way to do a roll Down test?

Alex Martinez had a roll down test spreadsheet using a hill.

I'd have to look it up but you could input your own data manually.

jaretj

Well, Golden Cheetah has aerolab which is a visual Chung/VE solver. A roll down can be treated that with power at zero.

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Developing aero, fit and other fun stuff at Red is Faster

I wrote an app to do it a few years ago that used your phone GPS and gave you instructions, but phone GPS units are so bad that it gave pretty unusable results. Would be better if it was tied to your PM's speed readings.

If you just want to compare setups without getting actual Cda values, a hill, consistent weather, and a stopwatch are really all you need. Start your roll at a consistent speed each time, alternate setups if possible to reduce the effect of changing conditions, and average the elapsed time of each roll.

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STAC Zero Trainer - Zero noise, zero tire contact, zero moving parts. Suffer in Silence starting fall 2016

That solver requires a pancake flat venue. If you see a storm drain on the side of the road that will be enough to make the estimate noisy.

Perhaps this page could help you:

http://forum.slowtwitch.com/gforum.cgi?post=3590873

So sorry I got the name wrong, it's Ale Martinez

jaretj

Okay, so I have the spread sheet downloaded.

Now I set my 910xt to 1 second recording, then I find a windless morning and flat road. I then make multiple coastdowns from varying speeds. How do I extract the 1 second data points?

Just figured it out. I can expand the speed data from the file set and can manually extract speed for every second. Labour intensive but should be easy.

Rather than re-enter all the data by hand it may be simpler to export from Garmin, and then convert to .csv.

You can use a flat road if you have one but you can also use a shallow downhill, or something with a dip in the middle.