See QuickRoute website for the one and only inspiration. Unfortunately, since my Mac is a bit old and running VMWare and the like are consuming, I no longer bother to launch it. But I still miss QuickRoute features! So I resolved to play a bit with GPS track files and QGis to get something similar.
For commodity, since I usually upload my Forerunner data to Garmin Connect, I start with a Garmin tcx file, not a gpx. Though a similar procedure can be applied on gpx, Garmin tcx already contains speed field for each point. That's one less thing to do!
- On Garmin Connect, select the desired activity and export as tcx