The Garmin 910XT is the premier GPS watch for triathlon training and racing.
You'll probably need a newer version of pyusb:
$ git clone git://github.com/walac/pyusb
There is no need to install it systemwide - you can simply leave it checked out somewhere.
Get the Garmin-Forerunner-610-Extractor project from GitHub:
$ git clone git://github.com/Tigge/Garmin-Forerunner-610-Extractor.git
Turn your watch on and plug in the USB adaptor.
You can now sync your activities:
$ sudo env PYTHONPATH=/path/to/pyusb ./garmin.py Request basic information... ANT version: AJK1.04RAF Capabilities: array('B', [8, 3, 0, 186, 54, 0]) Serial number: 3480039 Starting system... Searching... Authenticating with Forerunner 910XT (3863343203) - Passkey: OK Downloading 1 file(s) Downloading 2013-09-03_21-09-32-80-19364.fit [..........]The first time you sync, you will have to authenticate on the watch itself. Downloading the activities will be much slower than you expect.
After the syncing has finished, don't forget to turn the watch off. If you are used to the Garmin Edge 800 (which turns itself off when you insert the USB cable) you will probably not have the habit of turning off the unit.
Rather confusingly, your .FIT files are available in the Xdg configuration folder. For example:
ls -l ~/.config/garmin-extractor/3863343203/activities/ -rw-r--r-- 1 root root 2688 Jun 9 15:23 2013-06-08_12-33-24-80-2688.fit -rw-r--r-- 1 root root 1171 Jun 9 15:23 2013-06-08_12-37-14-80-1171.fit -rw-r--r-- 1 root root 6111 Jun 9 15:23 2013-06-08_22-19-28-80-6111.fit -rw-r--r-- 1 root root 170327 Jun 9 15:26 2013-06-09_11-09-44-80-170327.fit
Strava supports these .fit files through the From File upload option.