njkayaker

If you choose to use any of the Garmin Edges, the navigation is much more reliable if you keep it on the map page and keep an eye on it.

The turn announcements are nice but it's not that hard to miss them. If you have the screen on a data page or the course points page, you might miss a turn and just keep on going.

The basic navigation these things provide is following a line on the screen.

If you look at the map and see your relationship to the magenta line, it's hard to get lost with them. (It's easy to get lost with a cuesheet)

If you set it up right, you'll get an off course warning, which means you should look at the map (you can get off course warning if they momentarily lose GPS reception).

If you go off course, you usually know about it fairly quickly. And, looking at the map periodically is a backup that will show you as no longer following the magenta line.

Getting back on course is as simple as turning around to return to the magenta line.

There are two types of "turn notifications":

1) course points included in the tcx file.
2) "turn guidance" (what Garmin calls it) that show big white arrows on the screen about 0.1 miles before the turn.

1) The "course points" are basically part of track following. These pop-up as icons (usually an arrow indicating direction) and a 10 character label (the truncated street name). These are how the units that don't have maps (like the 500/510) can provide turn notifications. These are not completely reliable because they are highly dependent on position (the placement of the course point on the map might not be exactly the position of the turn in the real world). The Garmins provide a page that lists these with the distance from the current location. Ridewithgps writes its cuesheet entries out as "course points" in the TCX file. You can add custom entries (like for rest stops) in ridewithgps and these will show up on the "course point" list.

2) The fancier "turn guidance" (big white arrows) works (more or less) like a car GPS. These are much easier to see than the little course points and they are much less position sensitive. The Garmins generate this turn guidance by "walking" the track file you've copied to the unit to see what roads on the installed map the track appears to use. Using a map to plan the route that is different from the map installed on the device can cause this calculated route to not be quite right. This is how the device also can calculate a route to a point/place you select. You can see the list of turns for the "calculated route" by pressing on the text at the top of the map screen.

The devices have options to recalculate the route if you go off course. On some of the units, this abandons your course and calculates a route that is the "shortest" way to the endpoint. This isn't what people expect. It's advisable to turn off the "recalculate" option.

Sometimes, this fancier turn guidance can stop working. Some of the Garmins are more reliable than others with this (the ancient 800 might be the most reliable). That the fancy turn guidance isn't working doesn't mean the basic track following is not working.

Often (sometimes), you can just reload the route and it will start working again. The routing can be more reliable for shorter routes and it's faster to restart shorter routes anyway. That means, you should probably break really long routes up into smaller segments. Routes that cross over themselves can cause problems too (you can split these routes up also).

You can use both turn guidance at the same time (or separately).

The file you load to the Garmin has to be a "track" file, which contains a list of points that accurately describes the turns and curve of the path you want to travel on. (If you see lots of straight lines that "cut corners", you might have loaded a "route" file, which won't work on the Edges.

It doesn't matter if the track files is a gpx or tcx file (except that tcx files can have "course points".

It takes some practice/experience using them.

The 800 has a known issue of not being able to record rides longer than around 180 miles. You want to be sure to restart recording before then (I've heard that hitting the lap button avoids this problem). I have no idea if the other units have a similar problem.