Originally Posted by
01 CAt Man Do
Okay, I think I follow you. So you upload a track file which which creates a more accurate map.
Yes (sort of).
"Map" is the wrong term. A map is a set of roads/paths (and lots of other information). "Course" is a better term.
A "course" or "track" or "route" is a path on a map (one particular path drawn on a map).
The Garmins (for example) do extra route processing on a course. The reason you want to use a "track" ("snapped" to roads) instead of a "route" is because the track
reduces the extra processing the Garmins do to follow a course.
That is, when you use a track, what the Garmin gives you (remember, it doese extra processing) is much, much more likely to match the course you planned. In other words, because a track indicates "all" the gps coordinates you have to hit, it constrains the Garmin processing (which means the course the Garmin produces will end-up matching (very closely) the course you planned). If you use a "route" (just the "major" turns), the Garmin has more freedom to figure-out the path between the "major" turns).
Originally Posted by
01 CAt Man Do
Can I assume then that the track file doesn't include turn by turn prompts?
No. With the tcx format track file from ridewithgps, you get turn-by-turn prompts (on the Garmin Edge 8x0).
Originally Posted by
01 CAt Man Do
If so you have to be watching the screen constantly to get your turns or am I wrong about that?
On the Garmin Edge 8x0, you can turn on "off course" warnings too. That is a secondary audible prompt.
Originally Posted by
01 CAt Man Do
No tracking system is perfect but not having to stop to look at maps all the time is just great.
This is an important thing to understand: you have to think (a bit) about what the navigation device is doing and how it works.