Originally Posted by
MagicHour
Golden Cheetah, may do it? and it's free.
http://goldencheetah.org
UPDATE Yeah just checked I'm on Mac OSX 10.9 too.
You can import data file from most devices, edit data within EDIT tab and then Activity>Export to .CSV, .TSX OR upload to Strava, Training Peaks, or RidewithGPS and I think you can export .GPX from there.
I just ran into this problem again myself: have a .csv file (sent to me from coach's Cycleops/Poweragent program) I want to upload to Strava, so need to convert to a friendly format.
I had been using PowerAgent myself, but just updated to OS X 11.1 El Capitan on Mac, and Poweragent won't run (7.8.28 anyway, the current offering from Powertap site, though I swear there was 7.10 something going around awhile back; dunno what happened there), so I went looking for a solution.
Golden Cheetah 3.2.0 will run on OS X 11 and will convert .csv to .tcx (among others) for uploading to Strava, GarminConnect (or whatever you want to do with it).
Hope that helps someone!